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How to plumb/control wood boiler with radiant & DHW & Storage

TuckerTerra
TuckerTerra Member Posts: 31
Hi! Let me start out by saying I AM NOT a plumber/heater. I am an electrician. My best friend is a plumber/heater but he has very little experience with solid fuel boilers. He is helping me with the whole system but is uncomfortable trying to come up with a solution that will do what I am trying to do.

I finally got a (new to me) wood boiler. It is a Buderus g201 in great shape. I know I have read that it is more of a coal boiler for for $300 and the shape it is in I figured it was a good one to start with.
With that being said, I am building a house mostly out of pocket so I do not have a ton of funds available to buy new fancy equipment.

Here is what I am trying to do; I have a 2600 sqft ranch (counting 1st floor only, not the basement). It has radiant in the slab and 1st floor. I currently have an oil boiler running the radiant. I have not got my DHW setup yet but plan to use a Indirect tank so I can use the wood boiler to assist with heating it. That is where the catch is with plumbing and control...

I do not have thermal storage yet but plan to get something (not sure what yet...). With the radiant I can use the storage water down to 100F (plus/minus). For the DHW obviously that wont work.

I DO NOT WANT the oil boiler to heat the thermal storage, and it has to be automatic because I am gone most weekends in the winter and need the oil boiler to automatically kick in when the wood boiler cools.

Most of the diagrams I have found appear to do 2 things:
1) the petroleum boiler heats the storage (or...)
2) the wood boiler hot water is just teed into the oil boiler hot water. I don't this I want that setup because if it needs to heat the water up a few more degrees for DHW it can if it goes through the oil boiler first....?

If my storage is 'say' 110F when the radiant calls for heat I want the system to pull of the tank until it cant any longer. The issue arises when the DHW calls and the storage is still only 110F then it needs to fire up the oil boiler to heat the water up.

I would somehow have to have a control setup to make it all work, but I haven't worked that out yet. I am thinking I will need a relay and aquastat so if just the radiant calls and the storage is above 100F the oil boiler wont fire. But if the storage is below 100F or DHW calls and the storage is below 140F the oil boiler fires. Obviously I need to control a valve going to storage as well that closes when the the wood boiler cools off.

I figured if the storage feeds the cold water supply of the oil boiler with a diverter valve then the oil boiler would only have to heat the water from 110F.

I attached an original diagram that I found on Tarm's website. Then I edited it how I thought I could make this work. Now I am looking for all your input and critiquing!!

I should mention that I intentionally placed the DHW tank on the supply before the diverter valve because I figured I can have that diverter valve set to 100F and it wont affect the DHW.
Again, in case the diagram isn't clear the storage hot water is fed to the return to the oil boiler, not the output.


Fire away! Tell me if this will work and what is wrong.

My design concept:



Original Design concept

Comments

  • hot_rod
    hot_rod Member Posts: 18,190
    You are on the right track with your piping logic. A few more ideas in here complete with wiring schematics

    A differential (solar) control is the key to controlling in and out of storage, or bringing in back up,

    https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_10_0.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    TuckerTerra
  • Jamie Hall
    Jamie Hall Member Posts: 20,416
    May I insert a gentle monkey wrench? You should -- and that's a very very strong should -- keep your domestic hot water at at least 120 and preferably 140, and then have a thermostatic mixing valve on the output to supply you use points. Why? Primary reason is that if you keep it cooler -- or allow it to stand cooler -- it becomes a nearly ideal incubator for all manner of undesirable little bugs, including Legionnaire's. Which you don't want. This may mean using the oil boiler as a booster -- or primary source -- for the domestic hot water.

    Otherwise, the control logic is a simple set of "if this [control parameter} then that {desired action] or then not that {what you don't want to have happen]". Write them down and make sure that the logic for each is what you want, and that they don't conflict.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • TuckerTerra
    TuckerTerra Member Posts: 31

    Thinking about it that won't work.... 

    I need to tie the cold return into the tanks someplace.

    I also need a circulator between the tanks and wood boiler, correct? When the boiler is at temp it kicks on, not rely on gravity....

  • TuckerTerra
    TuckerTerra Member Posts: 31
    May I insert a gentle monkey wrench? You should -- and that's a very very strong should -- keep your domestic hot water at at least 120 and preferably 140, and then have a thermostatic mixing valve on the output to supply you use points. Why? Primary reason is that if you keep it cooler -- or allow it to stand cooler -- it becomes a nearly ideal incubator for all manner of undesirable little bugs, including Legionnaire's. Which you don't want. This may mean using the oil boiler as a booster -- or primary source -- for the domestic hot water. Otherwise, the control logic is a simple set of "if this [control parameter} then that {desired action] or then not that {what you don't want to have happen]". Write them down and make sure that the logic for each is what you want, and that they don't conflict.
    Yeah, I agree with you. That's why I was thinking the wood boiler supply should go to the oil boiler return in case it needs to be warmed up further.

    I think I'll be able to get the controls figured out. Between using that link posted above and my own (electrician) mind I understand controls well enough to control valves and circulators with relays. I don't believe it is too complicated control wise to do what I want.... I am just unfamiliar and questioning the physics portion of the way to plumb it up to not have issues.
  • leonz
    leonz Member Posts: 682
    The simplest way to do this is install a great deal of hot water storage and then connect each zone to one set of coils in the tank and have one set of coils connected to the oil boiler for heating when the wood boiler goes cold and the fire is out.

    You also want one set of coils and a small circulator to heat the domestic hot water tanks coil as well.

    The folks at Northern lights have circular tanks up to 5,000 gallons in capacity that can be brought through doorways and are assembled with simple hand tools and labor. They claim with proof apparently that thier tanks only lose 1 degree of temperature per hour.

    You could also one circulator pumping away from the wood/coal boiler to the tank to simply recirculate the water from the tank to the boiler and connect a small circulator to each coil in the tank to heat the zones and the domestic hot water coil.

    You have to remember first and foremost that 3 circulators pushing 7 gallons per minute will be 21 gallons per minute-1,260 gallons per hour and that water will be returning to the tank at a lower temperature to be reheated by the hot water being circulated by the boiler to heat all the water in the tank.

    If you use an 8 gallon per minute circulator to heat the water in the tank using one of the coils you will be pushing 480 gallons per hour through the coil and back to the boiler. At 8 gallons per minute it will take a little over 10 hours to have a complete exchange of hot water.

    If you have the high limit set at 160 degrees Fahrenheit and low limit set at 140 degrees Fahrenheit the boiler water will heat sooner and recover sooner.

    Let's say you invest in the 5,000 gallon water tank; with the above circulators you will have one complete
    exchange of water for heating the home and domestic water every 4 hours; 6 times per day; 7 days per week.

    The more water you have the more useable thermal mass you will be able to create and use even at lower
    temperatures as it will take less wood to heat it.



  • Zman
    Zman Member Posts: 7,433
    You might consider reverse indirect to combine your storage needs and the DHW. You could then use a smart mixing valve for your infloor and a tempering valve for the DHW. That would probably mean that the back boiler would end up heating the buffer. IMO that would be a reasonable trade-off for simplifying the design
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 18,190
    what do what do you have for storage tanks?
    The boiler has a pump on that return temperature device, number 6

    There is another way to pipe the tanks that would allow direct to load. The way you have it piped both tanks need to be hot before the system gets heat

    With a two pipe the wood boiler feeds directly into the loop, and charges the tank as the load drops off, or is satisfied 
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • TuckerTerra
    TuckerTerra Member Posts: 31
    edited August 2022
    leonz said:
    The simplest way to do this is install a great deal of hot water storage and then connect each zone to one set of coils in the tank and have one set of coils connected to the oil boiler for heating when the wood boiler goes cold and the fire is out. You also want one set of coils and a small circulator to heat the domestic hot water tanks coil as well. The folks at Northern lights have circular tanks up to 5,000 gallons in capacity that can be brought through doorways and are assembled with simple hand tools and labor. They claim with proof apparently that thier tanks only lose 1 degree of temperature per hour. You could also one circulator pumping away from the wood/coal boiler to the tank to simply recirculate the water from the tank to the boiler and connect a small circulator to each coil in the tank to heat the zones and the domestic hot water coil. You have to remember first and foremost that 3 circulators pushing 7 gallons per minute will be 21 gallons per minute-1,260 gallons per hour and that water will be returning to the tank at a lower temperature to be reheated by the hot water being circulated by the boiler to heat all the water in the tank. If you use an 8 gallon per minute circulator to heat the water in the tank using one of the coils you will be pushing 480 gallons per hour through the coil and back to the boiler. At 8 gallons per minute it will take a little over 10 hours to have a complete exchange of hot water. If you have the high limit set at 160 degrees Fahrenheit and low limit set at 140 degrees Fahrenheit the boiler water will heat sooner and recover sooner. Let's say you invest in the 5,000 gallon water tank; with the above circulators you will have one complete exchange of water for heating the home and domestic water every 4 hours; 6 times per day; 7 days per week. The more water you have the more useable thermal mass you will be able to create and use even at lower temperatures as it will take less wood to heat it.
    I understand what you're trying to say. I will say however that my house is well insulated and I will also be having a woodstove on my first floor so heating won't be an issue. The oil boiler is a 172,000 btu and the wood boiler is rated at 136,000 btu. 
    I want to add thermal storage but it is not important enough to me to fill my basement with a 5000 gallon storage tank that will be useful 4 months of the year.

    How long would it take for a 136k btu wood stove to heat up 5000 gallons from 140 to 180? 5000gal times 8lbs is 40,000lbs. 40,000lbs times 40 degrees is 1,600,000 btus devideded by 136,000 btu/hrs is almost 12 hrs. (which we all know isn't realistic, it'll probably be closer to 100,000 btu which would put the time closer to 16 hours. That doesn't even take into consideration if any heat is being drawn off which it will be.

    I can't sit there an tend the boiler for 12-16 hours straight every time the storage cools.
  • TuckerTerra
    TuckerTerra Member Posts: 31
    Zman said:
    You might consider reverse indirect to combine your storage needs and the DHW. You could then use a smart mixing valve for your infloor and a tempering valve for the DHW. That would probably mean that the back boiler would end up heating the buffer. IMO that would be a reasonable trade-off for simplifying the design
    I'll have to look that up. If I didn't care about the backup heating the storage it would be simple. I just feel like that is a waste of energy.
  • TuckerTerra
    TuckerTerra Member Posts: 31
    hot_rod said:
    what do what do you have for storage tanks?
    The boiler has a pump on that return temperature device, number 6

    There is another way to pipe the tanks that would allow direct to load. The way you have it piped both tanks need to be hot before the system gets heat

    With a two pipe the wood boiler feeds directly into the loop, and charges the tank as the load drops off, or is satisfied 
    Ohh I was not aware that #6 was a pump, thought it just a diverter. That diagram is just one from Tarm. Just a concept.

    That is a good point, I only care about storage after the load is satisfied. I don't want the boiler to idle is all. Are you saying to take two pipes off the top of the boiler instead of one; have one go to the tanks and the other go to the loop? Then when the zones stop calling it ships the heat to the tank...?
  • hot_rod
    hot_rod Member Posts: 18,190
    Two pipe buffer is what they commonly use with pellet boilers, and a much smaller buffer tank.
    So as soon as the boiler itself warms up above 140 or so you send heat directly to the load. If the load is zoned or smaller than the boiler output, the extra btus flow into the buffer. When the heat load satisfies the buffer x charges, ready for the meme t call
    Any  back up boiler bypasses the buffer, right to the load. Now if the backup boiler is grossly oversized you might want it connected to the buffer also?

    Ill send a couple sketches tomorrow

    meanwhile the concept of 2 pipe is here

    https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_17_na.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • leonz
    leonz Member Posts: 682
    edited August 2022

    Hi! Let me start out by saying I AM NOT a plumber/heater. I am an electrician. My best friend is a plumber/heater but he has very little experience with solid fuel boilers. He is helping me with the whole system but is uncomfortable trying to come up with a solution that will do what I am trying to do.

    I finally got a (new to me) wood boiler. It is a Buderus g201 in great shape. I know I have read that it is more of a coal boiler for for $300 and the shape it is in I figured it was a good one to start with.
    With that being said, I am building a house mostly out of pocket so I do not have a ton of funds available to buy new fancy equipment.

    Here is what I am trying to do; I have a 2600 sqft ranch (counting 1st floor only, not the basement). It has radiant in the slab and 1st floor. I currently have an oil boiler running the radiant. I have not got my DHW setup yet but plan to use a Indirect tank so I can use the wood boiler to assist with heating it. That is where the catch is with plumbing and control...

    I do not have thermal storage yet but plan to get something (not sure what yet...). With the radiant I can use the storage water down to 100F (plus/minus). For the DHW obviously that wont work.

    I DO NOT WANT the oil boiler to heat the thermal storage, and it has to be automatic because I am gone most weekends in the winter and need the oil boiler to automatically kick in when the wood boiler cools.

    Most of the diagrams I have found appear to do 2 things:
    1) the petroleum boiler heats the storage (or...)
    2) the wood boiler hot water is just teed into the oil boiler hot water. I don't this I want that setup because if it needs to heat the water up a few more degrees for DHW it can if it goes through the oil boiler first....?

    If my storage is 'say' 110F when the radiant calls for heat I want the system to pull of the tank until it cant any longer. The issue arises when the DHW calls and the storage is still only 110F then it needs to fire up the oil boiler to heat the water up.

    I would somehow have to have a control setup to make it all work, but I haven't worked that out yet. I am thinking I will need a relay and aquastat so if just the radiant calls and the storage is above 100F the oil boiler wont fire. But if the storage is below 100F or DHW calls and the storage is below 140F the oil boiler fires. Obviously I need to control a valve going to storage as well that closes when the the wood boiler cools off.

    I figured if the storage feeds the cold water supply of the oil boiler with a diverter valve then the oil boiler would only have to heat the water from 110F.

    I attached an original diagram that I found on Tarm's website. Then I edited it how I thought I could make this work. Now I am looking for all your input and critiquing!!

    I should mention that I intentionally placed the DHW tank on the supply before the diverter valve because I figured I can have that diverter valve set to 100F and it wont affect the DHW.
    Again, in case the diagram isn't clear the storage hot water is fed to the return to the oil boiler, not the output.

    Fire away! Tell me if this will work and what is wrong.

    My design concept:


    Original Design concept


    leonz said:

    The simplest way to do this is install a great deal of hot water storage and then connect each zone to one set of coils in the tank and have one set of coils connected to the oil boiler for heating when the wood boiler goes cold and the fire is out.

    You also want one set of coils and a small circulator to heat the domestic hot water tanks coil as well.

    The folks at Northern lights have circular tanks up to 5,000 gallons in capacity that can be brought through doorways and are assembled with simple hand tools and labor. They claim with proof apparently that thier tanks only lose 1 degree of temperature per hour.

    You could also one circulator pumping away from the wood/coal boiler to the tank to simply recirculate the water from the tank to the boiler and connect a small circulator to each coil in the tank to heat the zones and the domestic hot water coil.

    You have to remember first and foremost that 3 circulators pushing 7 gallons per minute will be 21 gallons per minute-1,260 gallons per hour and that water will be returning to the tank at a lower temperature to be reheated by the hot water being circulated by the boiler to heat all the water in the tank.

    If you use an 8 gallon per minute circulator to heat the water in the tank using one of the coils you will be pushing 480 gallons per hour through the coil and back to the boiler. At 8 gallons per minute it will take a little over 10 hours to have a complete exchange of hot water.

    If you have the high limit set at 160 degrees Fahrenheit and low limit set at 140 degrees Fahrenheit the boiler water will heat sooner and recover sooner.

    Let's say you invest in the 5,000 gallon water tank; with the above circulators you will have one complete
    exchange of water for heating the home and domestic water every 4 hours; 6 times per day; 7 days per week.

    The more water you have the more useable thermal mass you will be able to create and use even at lower
    temperatures as it will take less wood to heat it.


    I understand what you're trying to say. I will say however that my house is well insulated and I will also be having a woodstove on my first floor so heating won't be an issue. The oil boiler is a 172,000 btu and the wood boiler is rated at 136,000 btu. 
    I want to add thermal storage but it is not important enough to me to fill my basement with a 5000 gallon storage tank that will be useful 4 months of the year.

    How long would it take for a 136k btu wood stove to heat up 5,000 gallons from 140 to 180? 5000gal times 8lbs is 40,000lbs. 40,000lbs times 40 degrees is 1,600,000 btus divided by 136,000 btu/hrs is almost 12 hrs. (which we all know isn't realistic, it'll probably be closer to 100,000 btu which would put the time closer to 16 hours. That doesn't even take into consideration if any heat is being drawn off which it will be.

    I can't sit there and tend the boiler for 12-16 hours straight every time the storage cools.

    ================================================================================================================================================================================================




    I take it you use Tucker Snowcats in your work? Their model 2000 Trail Boss is an impressive unit.

    You have never burned wood or coal for heat I take it? A coal or wood fire properly tended and banked will heat a home for 12 hours or more, and even longer with coal.

    Setting the boiler high limit to 160 degrees Fahrenheit low limit and 180 degrees high limit will create more hot water to use and reduce the time it takes to heat the water.

    You are going to have to set up the controls as a master and slave arrangement with the wood and coal boiler being the slave to the oil boiler.

    You will need to set it up and plumb in one circulator to balance the water temperature between the two boilers running continuously and in doing so the oil boiler will start if the wood fire goes out as long as the system has power.

    A second circulator that is hooked to a zone other than the in floor heat can act as the dump zone circulator if the boiler overheats.

    If the Buderus boiler is burning and the power goes out the shutter motor will go off and the damper door/doors will shut and kill the fire.

    Is the Buderus wood and coal boiler draft controlled with a shutter motor or a manually adjustable bimetallic temperature control with a chain connected to the draft door/doors?

    The wood/coal boiler you have will not require a great deal of tending when you start burning wood and or Anthracite Coal as long as it is installed properly with a barometric damper in the oil boiler chimney if you do not have two block tile lined chimneys.

    If this is not the case and you only have one chimney to use you need to use a draft inducer for the oil burner and install the flue pipe and draft inducer according to code above the roof line and use the
    chimney for the wood and coal boiler.

    If your home is tight you will also need to introduce combustion air from the outside with a PVC pipe with a slotted drain cap from the outside piped near the floor by the wood and coal boiler.

    The air inlet point has to be away from the draft inducer and chimney.

    Keep in mind that the chimney has to be taller than the ridge line of the home to prevent down drafts and if it is not, it will require a chimney extension with a chimney cap. I have a Rockford Chimney Supply chimney extension with a chimney cap and it is a very high quality stainless steel chimney extension.

  • Hot_water_fan
    Hot_water_fan Member Posts: 1,003
    That boiler has a pretty small loading capacity yeah? Will you really want to tend to it that much? You can get wood boilers that are higher efficiency and handle larger loads. 
  • TuckerTerra
    TuckerTerra Member Posts: 31
    hot_rod said:
    Two pipe buffer is what they commonly use with pellet boilers, and a much smaller buffer tank.
    So as soon as the boiler itself warms up above 140 or so you send heat directly to the load. If the load is zoned or smaller than the boiler output, the extra btus flow into the buffer. When the heat load satisfies the buffer x charges, ready for the meme t call
    Any  back up boiler bypasses the buffer, right to the load. Now if the backup boiler is grossly oversized you might want it connected to the buffer also?

    Ill send a couple sketches tomorrow

    meanwhile the concept of 2 pipe is here

    https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_17_na.pdf
    That is exactly what I am trying to do. I will take a look at that and see if I can make some sense of it. Someone told me they saved money by having their backup hooked to the storage but I can't see how that would be true.
  • TuckerTerra
    TuckerTerra Member Posts: 31
    leonz said:
    Hi! Let me start out by saying I AM NOT a plumber/heater. I am an electrician. My best friend is a plumber/heater but he has very little experience with solid fuel boilers. He is helping me with the whole system but is uncomfortable trying to come up with a solution that will do what I am trying to do. I finally got a (new to me) wood boiler. It is a Buderus g201 in great shape. I know I have read that it is more of a coal boiler for for $300 and the shape it is in I figured it was a good one to start with. With that being said, I am building a house mostly out of pocket so I do not have a ton of funds available to buy new fancy equipment. Here is what I am trying to do; I have a 2600 sqft ranch (counting 1st floor only, not the basement). It has radiant in the slab and 1st floor. I currently have an oil boiler running the radiant. I have not got my DHW setup yet but plan to use a Indirect tank so I can use the wood boiler to assist with heating it. That is where the catch is with plumbing and control... I do not have thermal storage yet but plan to get something (not sure what yet...). With the radiant I can use the storage water down to 100F (plus/minus). For the DHW obviously that wont work. I DO NOT WANT the oil boiler to heat the thermal storage, and it has to be automatic because I am gone most weekends in the winter and need the oil boiler to automatically kick in when the wood boiler cools. Most of the diagrams I have found appear to do 2 things: 1) the petroleum boiler heats the storage (or...) 2) the wood boiler hot water is just teed into the oil boiler hot water. I don't this I want that setup because if it needs to heat the water up a few more degrees for DHW it can if it goes through the oil boiler first....? If my storage is 'say' 110F when the radiant calls for heat I want the system to pull of the tank until it cant any longer. The issue arises when the DHW calls and the storage is still only 110F then it needs to fire up the oil boiler to heat the water up. I would somehow have to have a control setup to make it all work, but I haven't worked that out yet. I am thinking I will need a relay and aquastat so if just the radiant calls and the storage is above 100F the oil boiler wont fire. But if the storage is below 100F or DHW calls and the storage is below 140F the oil boiler fires. Obviously I need to control a valve going to storage as well that closes when the the wood boiler cools off. I figured if the storage feeds the cold water supply of the oil boiler with a diverter valve then the oil boiler would only have to heat the water from 110F. I attached an original diagram that I found on Tarm's website. Then I edited it how I thought I could make this work. Now I am looking for all your input and critiquing!! I should mention that I intentionally placed the DHW tank on the supply before the diverter valve because I figured I can have that diverter valve set to 100F and it wont affect the DHW. Again, in case the diagram isn't clear the storage hot water is fed to the return to the oil boiler, not the output. Fire away! Tell me if this will work and what is wrong. My design concept: Original Design concept
    leonz said:
    The simplest way to do this is install a great deal of hot water storage and then connect each zone to one set of coils in the tank and have one set of coils connected to the oil boiler for heating when the wood boiler goes cold and the fire is out. You also want one set of coils and a small circulator to heat the domestic hot water tanks coil as well. The folks at Northern lights have circular tanks up to 5,000 gallons in capacity that can be brought through doorways and are assembled with simple hand tools and labor. They claim with proof apparently that thier tanks only lose 1 degree of temperature per hour. You could also one circulator pumping away from the wood/coal boiler to the tank to simply recirculate the water from the tank to the boiler and connect a small circulator to each coil in the tank to heat the zones and the domestic hot water coil. You have to remember first and foremost that 3 circulators pushing 7 gallons per minute will be 21 gallons per minute-1,260 gallons per hour and that water will be returning to the tank at a lower temperature to be reheated by the hot water being circulated by the boiler to heat all the water in the tank. If you use an 8 gallon per minute circulator to heat the water in the tank using one of the coils you will be pushing 480 gallons per hour through the coil and back to the boiler. At 8 gallons per minute it will take a little over 10 hours to have a complete exchange of hot water. If you have the high limit set at 160 degrees Fahrenheit and low limit set at 140 degrees Fahrenheit the boiler water will heat sooner and recover sooner. Let's say you invest in the 5,000 gallon water tank; with the above circulators you will have one complete exchange of water for heating the home and domestic water every 4 hours; 6 times per day; 7 days per week. The more water you have the more useable thermal mass you will be able to create and use even at lower temperatures as it will take less wood to heat it.
    I understand what you're trying to say. I will say however that my house is well insulated and I will also be having a woodstove on my first floor so heating won't be an issue. The oil boiler is a 172,000 btu and the wood boiler is rated at 136,000 btu. 
    I want to add thermal storage but it is not important enough to me to fill my basement with a 5000 gallon storage tank that will be useful 4 months of the year.

    How long would it take for a 136k btu wood stove to heat up 5,000 gallons from 140 to 180? 5000gal times 8lbs is 40,000lbs. 40,000lbs times 40 degrees is 1,600,000 btus divided by 136,000 btu/hrs is almost 12 hrs. (which we all know isn't realistic, it'll probably be closer to 100,000 btu which would put the time closer to 16 hours. That doesn't even take into consideration if any heat is being drawn off which it will be.

    I can't sit there and tend the boiler for 12-16 hours straight every time the storage cools.
    ================================================================================================================================================================================================ I take it you use Tucker Snowcats in your work?
    Their model 2000 Trail Boss is an impressive unit.
    Not for work but for play! They are very well built, a lot of well thought ideas! Very fun to operate!

     You have never burned wood or coal for heat I take it? A coal or wood fire properly tended and banked will heat a home for 12 hours or more, and even longer with coal.

    Yeah I grew up with woodstoves and that is how I currently heat. Never used a wood boiler though. I know woodstoves can burn for that duration but I was told not to expect those burn times out of a boiler unless it sits idle which is not efficient. 
     Setting the boiler high limit to 160 degrees Fahrenheit low limit and 180 degrees high limit will create more hot water to use and reduce the time it takes to heat the water.
    understandable, just like an electric water heater.

     You are going to have to set up the controls as a master and slave arrangement with the wood and coal boiler being the slave to the oil boiler. You will need to set it up and plumb in one circulator to balance the water temperature between the two boilers running continuously and in doing so the oil boiler will start if the wood fire goes out as long as the system has power.
    that's exactly what I was thinking but only when the wood is up to temp.....correct?
     A second circulator that is hooked to a zone other than the in floor heat can act as the dump zone circulator if the boiler overheats.
    can I use the storage as dump zone?
     If the Buderus boiler is burning and the power goes out the shutter motor will go off and the damper door/doors will shut and kill the fire. Is the Buderus wood and coal boiler draft controlled with a shutter motor or a manually adjustable bimetallic temperature control with a chain connected to the draft door/doors?
    the damper is manual with a chain. However, I do have an automatic backup generator to run everything if utility power fails.


     The wood/coal boiler you have will not require a great deal of tending when you start burning wood and or Anthracite Coal as long as it is installed properly with a barometric damper in the oil boiler chimney if you do not have two block tile lined chimneys. If this is not the case and you only have one chimney to use you need to use a draft inducer for the oil burner and install the flue pipe and draft inducer according to code above the roof line and use the chimney for the wood and coal boiler.
    I have a brand new 3 flu masonry chimney, 1 flu for oil boiler, 1 flu for wood boiler, 1 flu for 1st floor woodstove. It is well above the roof ridge. 

     If your home is tight you will also need to introduce combustion air from the outside with a PVC pipe with a slotted drain cap from the outside piped near the floor by the wood and coal boiler. The air inlet point has to be away from the draft inducer and chimney. Keep in mind that the chimney has to be taller than the ridge line of the home to prevent down drafts and if it is not, it will require a chimney extension with a chimney cap. I have a Rockford Chimney Supply chimney extension with a chimney cap and it is a very high quality stainless steel chimney extension. 
    I have already put thought into a makeup air unit or ERV for this reason.  Was going to see if I need one first though.



    Thanks for taking time to reply and information!!!
  • TuckerTerra
    TuckerTerra Member Posts: 31
    That boiler has a pretty small loading capacity yeah? Will you really want to tend to it that much? You can get wood boilers that are higher efficiency and handle larger loads. 
    True, I agree. Hoping to not have to tend it too often if I add storage to the system. 

    Id love to get a newer more efficient boiler but building a 2600ft ranch out of pocket for me doesn't allow for the type of money to get a newer setup. This boiler cost $300. Newer gasification ones are probably around $10k now
  • leonz
    leonz Member Posts: 682


    leonz said:

    Hi! Let me start out by saying I AM NOT a plumber/heater. I am an electrician. My best friend is a plumber/heater but he has very little experience with solid fuel boilers. He is helping me with the whole system but is uncomfortable trying to come up with a solution that will do what I am trying to do.

    I finally got a (new to me) wood boiler. It is a Buderus g201 in great shape. I know I have read that it is more of a coal boiler for for $300 and the shape it is in I figured it was a good one to start with.
    With that being said, I am building a house mostly out of pocket so I do not have a ton of funds available to buy new fancy equipment.

    Here is what I am trying to do; I have a 2600 sqft ranch (counting 1st floor only, not the basement). It has radiant in the slab and 1st floor. I currently have an oil boiler running the radiant. I have not got my DHW setup yet but plan to use a Indirect tank so I can use the wood boiler to assist with heating it. That is where the catch is with plumbing and control...

    I do not have thermal storage yet but plan to get something (not sure what yet...). With the radiant I can use the storage water down to 100F (plus/minus). For the DHW obviously that wont work.

    I DO NOT WANT the oil boiler to heat the thermal storage, and it has to be automatic because I am gone most weekends in the winter and need the oil boiler to automatically kick in when the wood boiler cools.

    Most of the diagrams I have found appear to do 2 things:
    1) the petroleum boiler heats the storage (or...)
    2) the wood boiler hot water is just teed into the oil boiler hot water. I don't this I want that setup because if it needs to heat the water up a few more degrees for DHW it can if it goes through the oil boiler first....?

    If my storage is 'say' 110F when the radiant calls for heat I want the system to pull of the tank until it cant any longer. The issue arises when the DHW calls and the storage is still only 110F then it needs to fire up the oil boiler to heat the water up.

    I would somehow have to have a control setup to make it all work, but I haven't worked that out yet. I am thinking I will need a relay and aquastat so if just the radiant calls and the storage is above 100F the oil boiler wont fire. But if the storage is below 100F or DHW calls and the storage is below 140F the oil boiler fires. Obviously I need to control a valve going to storage as well that closes when the the wood boiler cools off.

    I figured if the storage feeds the cold water supply of the oil boiler with a diverter valve then the oil boiler would only have to heat the water from 110F.

    I attached an original diagram that I found on Tarm's website. Then I edited it how I thought I could make this work. Now I am looking for all your input and critiquing!!

    I should mention that I intentionally placed the DHW tank on the supply before the diverter valve because I figured I can have that diverter valve set to 100F and it wont affect the DHW.
    Again, in case the diagram isn't clear the storage hot water is fed to the return to the oil boiler, not the output.

    Fire away! Tell me if this will work and what is wrong.

    My design concept:


    Original Design concept

    leonz said:

    The simplest way to do this is install a great deal of hot water storage and then connect each zone to one set of coils in the tank and have one set of coils connected to the oil boiler for heating when the wood boiler goes cold and the fire is out.

    You also want one set of coils and a small circulator to heat the domestic hot water tanks coil as well.

    The folks at Northern lights have circular tanks up to 5,000 gallons in capacity that can be brought through doorways and are assembled with simple hand tools and labor. They claim with proof apparently that thier tanks only lose 1 degree of temperature per hour.

    You could also one circulator pumping away from the wood/coal boiler to the tank to simply recirculate the water from the tank to the boiler and connect a small circulator to each coil in the tank to heat the zones and the domestic hot water coil.

    You have to remember first and foremost that 3 circulators pushing 7 gallons per minute will be 21 gallons per minute-1,260 gallons per hour and that water will be returning to the tank at a lower temperature to be reheated by the hot water being circulated by the boiler to heat all the water in the tank.

    If you use an 8 gallon per minute circulator to heat the water in the tank using one of the coils you will be pushing 480 gallons per hour through the coil and back to the boiler. At 8 gallons per minute it will take a little over 10 hours to have a complete exchange of hot water.

    If you have the high limit set at 160 degrees Fahrenheit and low limit set at 140 degrees Fahrenheit the boiler water will heat sooner and recover sooner.

    Let's say you invest in the 5,000 gallon water tank; with the above circulators you will have one complete
    exchange of water for heating the home and domestic water every 4 hours; 6 times per day; 7 days per week.

    The more water you have the more useable thermal mass you will be able to create and use even at lower
    temperatures as it will take less wood to heat it.


    I understand what you're trying to say. I will say however that my house is well insulated and I will also be having a woodstove on my first floor so heating won't be an issue. The oil boiler is a 172,000 btu and the wood boiler is rated at 136,000 btu. 
    I want to add thermal storage but it is not important enough to me to fill my basement with a 5000 gallon storage tank that will be useful 4 months of the year.

    How long would it take for a 136k btu wood stove to heat up 5,000 gallons from 140 to 180? 5000gal times 8lbs is 40,000lbs. 40,000lbs times 40 degrees is 1,600,000 btus divided by 136,000 btu/hrs is almost 12 hrs. (which we all know isn't realistic, it'll probably be closer to 100,000 btu which would put the time closer to 16 hours. That doesn't even take into consideration if any heat is being drawn off which it will be.

    I can't sit there and tend the boiler for 12-16 hours straight every time the storage cools.

    ================================================================================================================================================================================================




    I take it you use Tucker Snowcats in your work?
    Their model 2000 Trail Boss is an impressive unit.
    Not for work but for play! They are very well built, a lot of well thought ideas! Very fun to operate!

     You have never burned wood or coal for heat I take it? A coal or wood fire properly tended and banked will heat a home for 12 hours or more, and even longer with coal.


    Yeah I grew up with woodstoves and that is how I currently heat. Never used a wood boiler though. I know woodstoves can burn for that duration but I was told not to expect those burn times out of a boiler unless it sits idle which is not efficient. 
     Setting the boiler high limit to 160 degrees Fahrenheit low limit and 180 degrees high limit will create more hot water to use and reduce the time it takes to heat the water.
    understandable, just like an electric water heater.

     You are going to have to set up the controls as a master and slave arrangement with the wood and coal boiler being the slave to the oil boiler.

    You will need to set it up and plumb in one circulator to balance the water temperature between the two boilers running continuously and in doing so the oil boiler will start if the wood fire goes out as long as the system has power.
    that's exactly what I was thinking but only when the wood is up to temp.....correct?
     A second circulator that is hooked to a zone other than the in floor heat can act as the dump zone circulator if the boiler overheats.

    can I use the storage as dump zone?
     If the Buderus boiler is burning and the power goes out the shutter motor will go off and the damper door/doors will shut and kill the fire.

    (yes you can use the water storage as dump zone )



    Is the Buderus wood and coal boiler draft controlled with a shutter motor or a manually adjustable bimetallic temperature control with a chain connected to the draft door/doors?


    the damper is manual with a chain. However, I do have an automatic backup generator to run everything if utility power fails.

    (Does the manual damper adjuster have a black temperature dial on the knob with a long arm????, if it does the damper is semi automatic and you still need a barometric damper sized for the stove pipe.)








     The wood/coal boiler you have will not require a great deal of tending when you start burning wood and or Anthracite Coal as long as it is installed properly with a barometric damper in the oil boiler chimney if you do not have two block tile lined chimneys.

    If this is not the case and you only have one chimney to use you need to use a draft inducer for the oil burner and install the flue pipe and draft inducer according to code above the roof line and use the
    chimney for the wood and coal boiler.




    I have a brand new 3 flu masonry chimney, 1 flu for oil boiler, 1 flu for wood boiler, 1 flu for 1st floor woodstove. It is well above the roof ridge. 

     

    (If you do not have them already you need chimney caps to prevent down drafts from entering the
    chimney)

    If your home is tight you will also need to introduce combustion air from the outside with a PVC pipe with a slotted drain cap from the outside piped near the floor by the wood and coal boiler.

    The air inlet point has to be away from the draft inducer and chimney.

    Keep in mind that the chimney has to be taller than the ridge line of the home to prevent down drafts and if it is not, it will require a chimney extension with a chimney cap. I have a Rockford Chimney Supply chimney extension with a chimney cap and it is a very high quality stainless steel chimney extension.


     
    I have already put thought into a makeup air unit or ERV for this reason.  Was going to see if I need one first though.



    Thanks for taking time to reply and information!!!


    (Putting in a 4 inch PVC pipe air inlet as far from the chimney as possible will keep the wood stove and wood boiler from creating a greater negative pressure gradient/vacuum and reduce the consumption of the ambient air in the home. You have to make sure the air inlet is well above the deepest snowpack and the elbow has a screen in it and is facing down).





  • hot_rod
    hot_rod Member Posts: 18,190
    If ever both the wood fired and oil fired run at the same time, you will need quite a bit combustion air. I doubt a 4” pvc will supply that?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 18,190
    Something like this. This has the backup direct to the loads
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • TuckerTerra
    TuckerTerra Member Posts: 31
    leonz said:
    leonz said:
    Hi! Let me start out by saying I AM NOT a plumber/heater. I am an electrician. My best friend is a plumber/heater but he has very little experience with solid fuel boilers. He is helping me with the whole system but is uncomfortable trying to come up with a solution that will do what I am trying to do. I finally got a (new to me) wood boiler. It is a Buderus g201 in great shape. I know I have read that it is more of a coal boiler for for $300 and the shape it is in I figured it was a good one to start with. With that being said, I am building a house mostly out of pocket so I do not have a ton of funds available to buy new fancy equipment. Here is what I am trying to do; I have a 2600 sqft ranch (counting 1st floor only, not the basement). It has radiant in the slab and 1st floor. I currently have an oil boiler running the radiant. I have not got my DHW setup yet but plan to use a Indirect tank so I can use the wood boiler to assist with heating it. That is where the catch is with plumbing and control... I do not have thermal storage yet but plan to get something (not sure what yet...). With the radiant I can use the storage water down to 100F (plus/minus). For the DHW obviously that wont work. I DO NOT WANT the oil boiler to heat the thermal storage, and it has to be automatic because I am gone most weekends in the winter and need the oil boiler to automatically kick in when the wood boiler cools. Most of the diagrams I have found appear to do 2 things: 1) the petroleum boiler heats the storage (or...) 2) the wood boiler hot water is just teed into the oil boiler hot water. I don't this I want that setup because if it needs to heat the water up a few more degrees for DHW it can if it goes through the oil boiler first....? If my storage is 'say' 110F when the radiant calls for heat I want the system to pull of the tank until it cant any longer. The issue arises when the DHW calls and the storage is still only 110F then it needs to fire up the oil boiler to heat the water up. I would somehow have to have a control setup to make it all work, but I haven't worked that out yet. I am thinking I will need a relay and aquastat so if just the radiant calls and the storage is above 100F the oil boiler wont fire. But if the storage is below 100F or DHW calls and the storage is below 140F the oil boiler fires. Obviously I need to control a valve going to storage as well that closes when the the wood boiler cools off. I figured if the storage feeds the cold water supply of the oil boiler with a diverter valve then the oil boiler would only have to heat the water from 110F. I attached an original diagram that I found on Tarm's website. Then I edited it how I thought I could make this work. Now I am looking for all your input and critiquing!! I should mention that I intentionally placed the DHW tank on the supply before the diverter valve because I figured I can have that diverter valve set to 100F and it wont affect the DHW. Again, in case the diagram isn't clear the storage hot water is fed to the return to the oil boiler, not the output. Fire away! Tell me if this will work and what is wrong. My design concept: Original Design concept
    leonz said:
    The simplest way to do this is install a great deal of hot water storage and then connect each zone to one set of coils in the tank and have one set of coils connected to the oil boiler for heating when the wood boiler goes cold and the fire is out. You also want one set of coils and a small circulator to heat the domestic hot water tanks coil as well. The folks at Northern lights have circular tanks up to 5,000 gallons in capacity that can be brought through doorways and are assembled with simple hand tools and labor. They claim with proof apparently that thier tanks only lose 1 degree of temperature per hour. You could also one circulator pumping away from the wood/coal boiler to the tank to simply recirculate the water from the tank to the boiler and connect a small circulator to each coil in the tank to heat the zones and the domestic hot water coil. You have to remember first and foremost that 3 circulators pushing 7 gallons per minute will be 21 gallons per minute-1,260 gallons per hour and that water will be returning to the tank at a lower temperature to be reheated by the hot water being circulated by the boiler to heat all the water in the tank. If you use an 8 gallon per minute circulator to heat the water in the tank using one of the coils you will be pushing 480 gallons per hour through the coil and back to the boiler. At 8 gallons per minute it will take a little over 10 hours to have a complete exchange of hot water. If you have the high limit set at 160 degrees Fahrenheit and low limit set at 140 degrees Fahrenheit the boiler water will heat sooner and recover sooner. Let's say you invest in the 5,000 gallon water tank; with the above circulators you will have one complete exchange of water for heating the home and domestic water every 4 hours; 6 times per day; 7 days per week. The more water you have the more useable thermal mass you will be able to create and use even at lower temperatures as it will take less wood to heat it.
    I understand what you're trying to say. I will say however that my house is well insulated and I will also be having a woodstove on my first floor so heating won't be an issue. The oil boiler is a 172,000 btu and the wood boiler is rated at 136,000 btu. 
    I want to add thermal storage but it is not important enough to me to fill my basement with a 5000 gallon storage tank that will be useful 4 months of the year.

    How long would it take for a 136k btu wood stove to heat up 5,000 gallons from 140 to 180? 5000gal times 8lbs is 40,000lbs. 40,000lbs times 40 degrees is 1,600,000 btus divided by 136,000 btu/hrs is almost 12 hrs. (which we all know isn't realistic, it'll probably be closer to 100,000 btu which would put the time closer to 16 hours. That doesn't even take into consideration if any heat is being drawn off which it will be.

    I can't sit there and tend the boiler for 12-16 hours straight every time the storage cools.
    ================================================================================================================================================================================================ I take it you use Tucker Snowcats in your work?
    Their model 2000 Trail Boss is an impressive unit.
    Not for work but for play! They are very well built, a lot of well thought ideas! Very fun to operate!

     You have never burned wood or coal for heat I take it? A coal or wood fire properly tended and banked will heat a home for 12 hours or more, and even longer with coal.

    Yeah I grew up with woodstoves and that is how I currently heat. Never used a wood boiler though. I know woodstoves can burn for that duration but I was told not to expect those burn times out of a boiler unless it sits idle which is not efficient. 
     Setting the boiler high limit to 160 degrees Fahrenheit low limit and 180 degrees high limit will create more hot water to use and reduce the time it takes to heat the water.
    understandable, just like an electric water heater.

     You are going to have to set up the controls as a master and slave arrangement with the wood and coal boiler being the slave to the oil boiler. You will need to set it up and plumb in one circulator to balance the water temperature between the two boilers running continuously and in doing so the oil boiler will start if the wood fire goes out as long as the system has power.
    that's exactly what I was thinking but only when the wood is up to temp.....correct?
     A second circulator that is hooked to a zone other than the in floor heat can act as the dump zone circulator if the boiler overheats.
    can I use the storage as dump zone?
     If the Buderus boiler is burning and the power goes out the shutter motor will go off and the damper door/doors will shut and kill the fire. (yes you can use the water storage as dump zone ) Is the Buderus wood and coal boiler draft controlled with a shutter motor or a manually adjustable bimetallic temperature control with a chain connected to the draft door/doors?
    the damper is manual with a chain. However, I do have an automatic backup generator to run everything if utility power fails. (Does the manual damper adjuster have a black temperature dial on the knob with a long arm????, if it does the damper is semi automatic and you still need a barometric damper sized for the stove pipe.)


     The wood/coal boiler you have will not require a great deal of tending when you start burning wood and or Anthracite Coal as long as it is installed properly with a barometric damper in the oil boiler chimney if you do not have two block tile lined chimneys. If this is not the case and you only have one chimney to use you need to use a draft inducer for the oil burner and install the flue pipe and draft inducer according to code above the roof line and use the chimney for the wood and coal boiler.
    I have a brand new 3 flu masonry chimney, 1 flu for oil boiler, 1 flu for wood boiler, 1 flu for 1st floor woodstove. It is well above the roof ridge. 

      (If you do not have them already you need chimney caps to prevent down drafts from entering the chimney) If your home is tight you will also need to introduce combustion air from the outside with a PVC pipe with a slotted drain cap from the outside piped near the floor by the wood and coal boiler. The air inlet point has to be away from the draft inducer and chimney. Keep in mind that the chimney has to be taller than the ridge line of the home to prevent down drafts and if it is not, it will require a chimney extension with a chimney cap. I have a Rockford Chimney Supply chimney extension with a chimney cap and it is a very high quality stainless steel chimney extension.  
    I have already put thought into a makeup air unit or ERV for this reason.  Was going to see if I need one first though.



    Thanks for taking time to reply and information!!!
    (Putting in a 4 inch PVC pipe air inlet as far from the chimney as possible will keep the wood stove and wood boiler from creating a greater negative pressure gradient/vacuum and reduce the consumption of the ambient air in the home. You have to make sure the air inlet is well above the deepest snowpack and the elbow has a screen in it and is facing down).
    The damper does have that black adjustment knob with the long arm on it
  • TuckerTerra
    TuckerTerra Member Posts: 31
    hot_rod said:
    If ever both the wood fired and oil fired run at the same time, you will need quite a bit combustion air. I doubt a 4” pvc will supply that?
    Yeah I have potential for major vacuum in the house even excluding the two boilers....  woodstove on the first floor, 600cfm kitchen hood, 400 cfm master shower fan, and 4 other 150cfm bathroom/toilet fans. Not that they would all be running at the same time, but the potential is there.
  • TuckerTerra
    TuckerTerra Member Posts: 31
    hot_rod said:
    Something like this. This has the backup direct to the loads
    Okay, that makes sense. Whats the point of the yellow line you have that connects the supply and output of the wood? I see that is common but didn't know why?
    This setup is much simpler but won't "reheat" the wood output if it isn't hot enough for DHW. Maybe that is dumb and I should just forget about that....
  • leonz
    leonz Member Posts: 682
    You need this manual. With manual temperature control you need to know how to run the boiler.
  • TuckerTerra
    TuckerTerra Member Posts: 31
    I'm going to throw a monkey wrench into my thoughts and try to consider if would be much easier/cheaper and simpler to just go with non-pressurized storage and keep the wood boiler and oil boiler separate with heat exchangers. I don't know if there would be a way to heat the load first without heating the storage this way.
  • TuckerTerra
    TuckerTerra Member Posts: 31
    leonz said:
    You need this manual. With manual temperature control you need to know how to run the boiler.
    Thank you for that! I was going to try to find one but you have saved me time!!  :)
  • leonz
    leonz Member Posts: 682

    I'm going to throw a monkey wrench into my thoughts and try to consider if would be much easier/cheaper and simpler to just go with non-pressurized storage and keep the wood boiler and oil boiler separate with heat exchangers. I don't know if there would be a way to heat the load first without heating the storage this way.

    =================================================================

    Check with the Northen Lights folks and ask them for help as they do a lot of water storage work.

  • hot_rod
    hot_rod Member Posts: 18,190
    hot_rod said:
    Something like this. This has the backup direct to the loads
    Okay, that makes sense. Whats the point of the yellow line you have that connects the supply and output of the wood? I see that is common but didn't know why?
    This setup is much simpler but won't "reheat" the wood output if it isn't hot enough for DHW. Maybe that is dumb and I should just forget about that....
    The yellow line is the bypass mix line to that loading unit at the boiler return. # 6 on your schematic, I think

    You really don’t want to heat the second fossil fuel boiler with the wood boiler, the boiler acts as a heat dump, let it fire as the wood boiler or buffer drops  to a low temperature. The system could be a simple manual switch over it a control that watches tank temperature and calls on the boiler.

    ThE Idronics issue on wood boilers has a few control wiring examples, also Idronics 6 which is solar, but the same control logic is used. As one source goes cool, the other takes over.

    Make sure you have good low level CO detectors, especially if you starve the fire or burners for combustion air. You will use up all the O2 in the home and suffocate. It happen to folks when the sleep, often times. Stay safe!


    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    TuckerTerra