Oil boiler and outdoor Wood Boiler

Kkane97

hot_rod said:

Your drawing showed 4 connections on the wood boiler. So you have two different independent systems

sounds like the boiler us large enough to handle both buildings at the same time?

do each building has its own piping Hx a
and controls

The pic if the manifold with pumos I assume is in the house? In a basement?

Yes the manifold with the oil boiler is in the house in the basement. 

Sorry I got confused by your drawing of what is what.
 What do you mean by "do each building has its own piping Hx a

and controls"

Kkane97

Nothing is piped yet for the OWB, I have it set in its location and am trying to draw out my plan for running the piping. Either as groundup simply with two pumps, one HX in the basement for the oil boiler and WtA heaters in the shop, or as hot_rod with hx in basement and shop.


I understand there's a lot of ways to skin an apple, cost out of the equation as far as system setup, I am confused as far as which method of hooking the system up would best fit what I want to do.

GroundUp

There is one thing that needs to be constant. You need to have 2 separate loops as I described, one to each building, each with its own circulator mounted at the boiler- both running 24/7 all winter. This is not negotiable under any circumstances, unless you fill the entire system with a proper solution of inhibited propylene glycol for freeze protection- which will cost you thousands by itself.

What you do with those loops is up to you, but 99% of OWB installs simply run said loops through the respective heat exchangers (HX) and back to the OWB. Shop goes from OWB through both unit heaters in series and back to OWB- that's it. House loops through plate HX and back to OWB- that's it.

Shop fans get controlled via thermostat(s). House runs as normal with the return water from the zones being preheated by the plate HX. Bypass the HX on the pressurized side with a 3 way zone valve if you feel so inclined, but I would not recommend that due to potential freeze protection issues.

Keep it simple, this is not rocket surgery.

Kkane97

this is my keep it simple plan, what would you change? what size should the circulator pump be for the heat exchanger? is it better to flow more water through the HX or less so heat can transfer longer?

if I use a variable speed pump to slow the flow down but maintain flow through the hX when the oil is up to temp i could use a pump like a 007-VSF5 or is there a simpler cheaper pump that could do the same thing? externally control a ecm pump?

@hot_rod is there still a benefit for having copper tube off the HX for a section before pex?

hot_rod

I agree with the two HX, one in each building.
I merely suggested a bypass pump with temperature control for some added efficiency.
It basically sends just enough heat out to the OWF to prevent freezing.
It adds additional two pumps and controls and additional $$
Up to you if that is worth it or not.

Kkane97

hot_rod said:

I agree with the two HX, one in each building. I merely suggested a bypass pump with temperature control for some added efficiency. It basically sends just enough heat out to the OWF to prevent freezing. It adds additional two pumps and controls and additional $$ Up to you if that is worth it or not.

Without a shunt pump on the pressurized side there is no way to maintain the core temp of the oil boiler unless a zone is calling for heat, doesnt it make more sense to have a flow constantly through the hx in the pressurized side?

Using a taco vt2218 with two temp sensors running the pump on delta T mode would efficiently do that? Variable speed pump in relation to temperature differential across the HX

leonz

GroundUp said:

Typically speaking, that exchanger just gets cut into the existing return line prior to re-entering the indoor boiler with no need for closely spaced tees. The circulator on the OWB runs 24/7 so that exchanger is always hot, and when any indoor zone is running, it will essentially preheat the return water entering the oil boiler via the aforementioned heat exchanger.

Is this garage attached or detached? If the former, maybe add it as a zone to your oil boiler so you also have backup? Otherwise just make a series or parallel loop out of it and hit all 3 exchangers at all times. If the latter, you'll want to run a separate loop from the OWB to that building also with its own circulator located on the OWB and just circulate 24/7 while controlling the fans with a thermostat. As for controlling the oil boiler, I would add an aquastat or Ranco type controller on the incoming OWB supply line at the heat exchanger and interrupt your oil boiler's TT signal with it, so that any time the OWB is above say 150*, the oil boiler will not fire. Whenever the OWB temp drops, the oil boiler will fire to make up the difference. If the OWB is something you don't intend to keep hot all the time during heating season, you may wish to have some sort of thermostatic bypass to prevent keeping the water jacket at oil boiler temp due to the 24/7 circulation of the OWB circ.

Regarding leonz, please disregard everything he/she said. It's 100% false.

------------------------------------------------------------------------------------------

This is the first time I have made a comment like this and hopefully the last.

You can be as insulting as you want to me but not even you can change the
laws of physics, thermal mass and how forest eaters work and don't work.




Leonz

hot_rod

Kkane97 said:

hot_rod said:

I agree with the two HX, one in each building. I merely suggested a bypass pump with temperature control for some added efficiency. It basically sends just enough heat out to the OWF to prevent freezing. It adds additional two pumps and controls and additional $$ Up to you if that is worth it or not.

Without a shunt pump on the pressurized side there is no way to maintain the core temp of the oil boiler unless a zone is calling for heat, doesnt it make more sense to have a flow constantly through the hx in the pressurized side?

Using a taco vt2218 with two temp sensors running the pump on delta T mode would efficiently do that? Variable speed pump in relation to temperature differential across the HX

Why do you want to maintain the core temperature if the oil boiler, that will waste heat up the flue
If the oil boiler us just for occasional freeze protection, keep it out of the loop until needed

Kkane97

hot_rod said:

Kkane97 said:

hot_rod said:

I agree with the two HX, one in each building. I merely suggested a bypass pump with temperature control for some added efficiency. It basically sends just enough heat out to the OWF to prevent freezing. It adds additional two pumps and controls and additional $$ Up to you if that is worth it or not.

Without a shunt pump on the pressurized side there is no way to maintain the core temp of the oil boiler unless a zone is calling for heat, doesnt it make more sense to have a flow constantly through the hx in the pressurized side?

Using a taco vt2218 with two temp sensors running the pump on delta T mode would efficiently do that? Variable speed pump in relation to temperature differential across the HX

Why do you want to maintain the core temperature if the oil boiler, that will waste heat up the flue
If the oil boiler us just for occasional freeze protection, keep it out of the loop until needed

Learning here, I thought it was better to store the heat in the oil boiler if the outdoor was running. So the shunt pump would only be beneficial if using it for freeze protection? Then simply remove the extra pump and flow will go through the HX only when a zone is calling for heat correct?

GroundUp

As HR said, there is really no purpose to keeping the oil boiler hotter than necessary unless there is a DHW coil which it does not sound like is the case. The extra 30 seconds it might take to start emitting heat when a zone calls is hardly worth the chimney loss, IMO. I'd forget about the wraparound/shunt altogether, personally. Having spent a good portion of my career working with these systems, I find no benefit without a DHW coil. Regarding the backfeed to the OWB during inactivity, that too will only happen during a call for heat. That Hawken is a pretty well insulated unit, so as long as you are using decent foamed underground lines like Thermopex or Rhinoflex, the parasitic loss should be minimal. Most systems I play with and own are low temp so obviously the backfeed is less than it would be with high temp like you have, but that's simple enough to mitigate with a 3 way valve and aquastat or Ranco type controller and only allowing it to backfeed enough to maintain maybe a 40 degree water jacket temp.

Kkane97

Where could I find a example of a three way to maintain a low own temp for backfeed? If I were to add that in. Would that be a three way with a sort of flow control  to limit the returned water to the owb when not in use?

I do not know the brand of underground that I got, but it is much nicer insulated looking to me than the thermopex I have seen, 1" pex lines

GroundUp

I don't know how to post links, but something like a Taco Sentry (Z100T3-2) on the pressurized side of the HX would allow the flow to be diverted around the HX depending on what the OWB temp is. If you were to employ a controller such as a Ranco ETC-112000-000 with the probe on the OWB supply line on the other side of the HX and set it to, say 45 degrees with a 5 degree differential, it could open and close that 3 way based on the OWB loop temp. Being the OWB loop is constantly circulating, there would be a constant reading on that supply line at the HX. When it falls below 40 degrees, the valve would open and allow flow from the oil boiler to backfeed the plate until the OWB reaches 45 degrees then revert back to closed. Then the OWB would always remain 40-45 degrees when not in use, minimizing your oil usage for backfeed. This would need to be manually switched, however, during times of OWB inactivity. Otherwise the hot OWB would never feed the indoor system as the bypass would always be open. Those lines are Rehau Insulpex, which are high quality.

Kkane97

i have buried the piping and set the boiler on its slab, so next is ordering what I need to hook into the rest of the system.

@GroundUp
I was looking into that controller for a different idea, using a small plate exchanger to heat my hottub, 120v pump that does not use a heating element just heats through the increase in temp of water flow, and controlling that circ with a temperature probe on the boiler side of that HX

This is how my system looks as of now, i know my pictures arent as a schematic uses symbols but it makes it easier for me to see what I want to do

I am concerned that running both the radiant zone and hottub zone for times soley will cause my return temps to be to low as far as condensate issues. so I was considering using a taco vt2218 pump with temperature probes as my boiler protection/ circ pump if i was to maintain boiler core temp from the outdoor unit.


I have added the three way bypass on the Boiler side of the HX because I was thinking it would be much simpler to plumb that change in and would still allow flow continuously to the OWB

@hot_rod as far as my older post regarding the circulator pump location in relation to the M port of my mixing valve, is this change correct?

Kkane97

Bump

GroundUp

I have told you several times the proper way to do this and you don't seem to care, so I am respectfully bowing out now. But no, a 2218 is not going to do anything for you as it's too small even wide open to provide adequate flow for your OWB. Plus, it can take minutes for the sensors to read and react when the flow has been slowed between heat calls.

Kkane97

GroundUp said:

I have told you several times the proper way to do this and you don't seem to care, so I am respectfully bowing out now. But no, a 2218 is not going to do anything for you as it's too small even wide open to provide adequate flow for your OWB. Plus, it can take minutes for the sensors to read and react when the flow has been slowed between heat calls.

im sorry it seems as I dont? I am trying to take everyones input together.

Is there a difference that would be of having the three way on the pressured side?

hot_rod

Hot supply into the H of the mix valve
Return goes to C port and back to system
Pump goes on mix port 
Some examples below 

A temperature controlled circ will only give you boiler protection if it can hydraulically disconnect the load
If supply from  a cold load is say 80 degrees, and the boiler is starting from cold, the pump cannot increase the boiler temperature, regardless how fast it spins🤨

piping below  shows better way to use a variable speed temperature control pump for protection 

Kkane97

hot_rod said:

Hot supply into the H of the mix valve
Return goes to C port and back to system
Pump goes on mix port 
Some examples below 

A temperature controlled circ will only give you boiler protection if it can hydraulically disconnect the load
If supply from  a cold load is say 80 degrees, and the boiler is starting from cold, the pump cannot increase the boiler temperature, regardless how fast it spins🤨

piping below  shows better way to use a variable speed temperature control pump for protection 

I don't see examples posted, that is how I have them in my diagram so I should be good to change as far as that, if you remember I have my pump on the return side of the mixing valve pulling through the zone off the m port

hot_rod

You could probably get a 1/2 dozen different opinions on how to pipe a system like yours

make a list if the “must haves” then decide if you want to enhance the operation and efficiency 

That will course will cost $$ and make a more complex system. Is it worth it or not, you need to decide

My opinion is parallel piping at the very least. Two options for freeze protection. How often are you leaving it unoccupied in winter? How much oil are you willing to use for freeze protection?  If it is one  week a winter, just bite the bullet on oil expense
Is return temperature protection a must  have? If so, I would use a 3 way valve instead of a thermostatic ECM controlled pump

Kkane97

hot_rod said:

You could probably get a 1/2 dozen different opinions on how to pipe a system like yours

make a list if the “must haves” then decide if you want to enhance the operation and efficiency 

That will course will cost $$ and make a more complex system. Is it worth it or not, you need to decide

My opinion is parallel piping at the very least. Two options for freeze protection. How often are you leaving it unoccupied in winter? How much oil are you willing to use for freeze protection?  If it is one  week a winter, just bite the bullet on oil expense
Is return temperature protection a must  have? If so, I would use a 3 way valve instead of a thermostatic ECM controlled pump

I would rather have freeze protection in place if I want to use it and go upstate snowmobiling. If I burn oil for a week to not run the outdoor wood stove during negative weeks of the winter, that's fine by me. Using a three-way valve as I have it on the outdoor wood boiler side to bypass past the heat exchanger inside, I need to have a pump on the oil boiler side to flow through the heat exchanger when the zones are not calling for heat but the outdoor wood stove for freeze protection is. Pump that I have on there should have no issue pumping around 16 gallons a minute. If I wanted to use that to be able to maintain core temperature of the boiler in the same way,  besides, the model of pump that I used is the way that I have it in my diagram okay? 

hot_rod

You may need to pump through all the piping to the house and back to protect both the boiler and piping from freezing? Most freeze ups that I dealt with were the piping at the back or where it entered the ground. Any wind moving under or around the boiler would cause a freeze and sometimes split tubing. So if a few- 5 gallons of oil is not a concern just let the pump run, the oil boiler run.

With either a 3 way valve inside, or the bypass pump idea, you could maintain the OWF with the oil to say 45 degrees, instead of running at the oil boiler temperature. So pulse just enough heat into the system to protect it. So either a 3 way valve and controller. Or and additional pump and controller.

You don’t need 16 gpm circulating in the boiler to freeze protect it, I doubt you are getting 16 gpm through the 1” Pex to the building. Or that you need 16 gpm

GroundUp

You will never get anywhere near 16 gpm through that loop with any circulator, and probably not even 8 gpm unless it's a behemoth of a circulator like a 26-150 or PL-55. Just FYI

leonz

If worse comes to worse, you can purchase a 55 gallon barrel of Hercules Cryo-tek-100 non toxic antifreeze to load up in your system and have the remaining antifreeze for make up fuid.

Global Industrial has it for $1,505.00 plus tax and frieght to your door, a drop gate/lift gate charge would add to the frieght cost.

Kkane97

hot_rod said:

You may need to pump through all the piping to the house and back to protect both the boiler and piping from freezing? Most freeze ups that I dealt with were the piping at the back or where it entered the ground. Any wind moving under or around the boiler would cause a freeze and sometimes split tubing. So if a few- 5 gallons of oil is not a concern just let the pump run, the oil boiler run.

With either a 3 way valve inside, or the bypass pump idea, you could maintain the OWF with the oil to say 45 degrees, instead of running at the oil boiler temperature. So pulse just enough heat into the system to protect it. So either a 3 way valve and controller. Or and additional pump and controller.

So where I have the 3 way valve mounted at the HX would be ok to bypass the oil boiler in the OWB loop then. all of the exterior piping will be flowing continuously and the three way valve bypass mounted inside at the HX. controller to set low limit for the bypass for freeze protection.

to do that I would need to have a circulator to run on the pressurized size when the three way opens for freeze protection. I have either missed it or have gotten confused. Is there anything wrong with my diagram, besides the pump model to do exactly that?

if i were to do a three way bypass, for energy efficiency I would want the bypass to close until the OWB reached say 40* but stay open if temperature is above say 140*

would this controller do that? one relay set to close at low limit temp and other set to open at high temp?
https://www.supplyhouse.com/Honeywell-T775M2006-Electronic-Temperature-Controller-with-2-Temperature-Inputs-2-Analog-Outputs-1-Sensor-Included

hot_rod

Id probably turn on freeze protection at 45 or so iff at 55ish. I don’t know why you would run up to 140f?  More oil consumption and higher heatloss at the OWF  the hotter you run

will you duplicate this  in the shop? What is the freeze protection for that building?

Kkane97

The 140 I meant for the three way to remain open above those temps as there would be a fire burning, if possible with two temp control it would automatically switch , if not I would manually

hot_rod

Can you get additional wires to the boiler from the house? A 120v circuit and some low voltage wires?

If so, here is how I would do a system. I think it is silly to run the OWF pump 24/7

If it is not in a freezing condition, or the fire has died and you are on oil heat, shut the OWF pump off.

The shunt pump with a control like you showed accomplishes this for probably the same $$ as the 3 way valve.

The control set at 40 degrees turns on the shunt pump and the OWF pump based on the temperature at the OWF rear end. Once it gets to 45 or 50, the OWF and shunt pump goes off, oil is just heating the home, and a minimum amount to the OWF.

Kkane97

hot_rod said:

Can you get additional wires to the boiler from the house? A 120v circuit and some low voltage wires? If so, here is how I would do a system. I think it is silly to run the OWF pump 24/7 If it is not in a freezing condition, or the fire has died and you are on oil heat, shut the OWF pump off. The shunt pump with a control like you showed accomplishes this for probably the same $$ as the 3 way valve. The control set at 40 degrees turns on the shunt pump and the OWF pump based on the temperature at the OWF rear end. Once it gets to 45 or 50, the OWF and shunt pump goes off, oil is just heating the home, and a minimum amount to the OWF.

I have ran a 1-in conduit in the trench next to the outdoor wood stove piping from both the shop and from the house. For either thermostat, or power for that so yes

Conduit is the far left pipe, center is owb  right is power feeding my sub panel in the shop which is the next project of cleaning that up




I was thinking the owb would continue to run 24/7 as the shop radiant loop is a factor.

Use that controller or one similar with two outputs to both control the zone valve for the two instances below 

If owb is over 140 ( just example temp ) the three way would maintain flow through the hx because the only way that would be so warm is if there is a fire burning. It would also help OWB recovery time as if it's lower than that it would be bypassing the HX.

If owb temp was to fall less than 40 the three way would also open until it reached its freeze temp temperature of say 50° and then go back to bypass.
 Do so with a 3 way NC valve,  it would purge heat into the owb as needed to maintain freeze temp, or leave it open for OWB heating


As you are saying 

Leave the shunt pump remove the three way, use the controller to turn on and off the shunt and owb pump respectfully in the same way?

What would you recommend for a shunt pump 

Is there a benefit to either way? Or is the way I was thinking incorrect? Like you said there's many different ways to set this up I just like weighing all the options and sorting out which fits best

hot_rod

The shunt pump could be a small Grundfos 15-58, speed 1.

To move 8 gpm, 80,000 BTU/ hr through that 1" pex would be (assumes your house heat load is 80,000 or less?)
8 gpm of 160•F water @ 12.8' head A Grundfos 26-99 for the OWF pump.

Yes the controller turns on the shunt and OWF pumps together when temperature drops to 40 or 45F. I'd like to see the sensor out at the OWF, the control could be inside.

Does the Hawkins have a controller to turn on the pump when it reaches temperature? or how is that pump controlled now?

The goal here is to have a system that automatically turns on a freeze protection mechanism. And to use the minimal amount of oil heat warming the OWF.

So if the fire burns out a day after you leave for a snowmobile trip, the system will take care of itself. Both the house heat and the freeze protection.
We are taking about one more pump and that controller you showed.

I believe 120V and a shielded sensor wire can be pulled in the same conduit. Pull a spare of each, so 2- 120V and 2- sensor wires (2 conductor)

This Ranco controller, sensor can extend up to 400'

Do the same for the shop.

Or throw in a LP unit heater with a 100lb tank for the small amount of freeze protection and some quick heat up redundancy

I've seen systems with a hot water coul in front of an LP unit heater so it is both hot water and LP. Seen farmer systems with and old truck radiator as the hot water hx

Kkane97

hot_rod said:

The shunt pump could be a small Grundfos 15-58, speed 1. To move 8 gpm, 80,000 BTU/ hr through that 1" pex would be (assumes your house heat load is 80,000 or less?) 8 gpm of 160•F water @ 12.8' head A Grundfos 26-99 for the OWF pump. Yes the controller turns on the shunt and OWF pumps together when temperature drops to 40 or 45F. I'd like to see the sensor out at the OWF, the control could be inside. Does the Hawkins have a controller to turn on the pump when it reaches temperature? or how is that pump controlled now? The goal here is to have a system that automatically turns on a freeze protection mechanism. And to use the minimal amount of oil heat warming the OWF. So if the fire burns out a day after you leave for a snowmobile trip, the system will take care of itself. Both the house heat and the freeze protection. We are taking about one more pump and that controller you showed. I believe 120V and a shielded sensor wire can be pulled in the same conduit. Pull a spare of each, so 2- 120V and 2- sensor wires (2 conductor) This Ranco controller, sensor can extend up to 400' Do the same for the shop. Or throw in a LP unit heater with a 100lb tank for the small amount of freeze protection and some quick heat up redundancy I've seen systems with a hot water coul in front of an LP unit heater so it is both hot water and LP. Seen farmer systems with and old truck radiator as the hot water hx

The shop has a 75,000 BTU mr. Heater big max in it now, but just one, it maintains the shop around 50° on a 20° day but sucks the propane down I have two 420 lb tanks for my standby generator that the LP unit also uses

hot_rod

Just use the lp in the shop to maintain 45- 50 degrees when the OWF is off. It is your backup and freeze protection that you already have.

So you don't have to do another OWF pumped freeze protection. The house boiler will do the freeze protection.

Heating two buildings with wood in an OWF. I hope you have a lot of wood cut
Dried wood, 4" or less in diameter will get you the best efficiency and least amount of creasote.

Kkane97

About 15 cords I run a repair business from the shop and maintain two fleets for tree companies. Wood gets dropped off all year long. 

Why would circulation alone of the OWF not be good enough to have freeze protection in the shop. The temperature of that water should be maintained by the indoor shunt pump warming the outdoor stove right?

hot_rod

Kkane97 said:

About 15 cords I run a repair business from the shop and maintain two fleets for tree companies. Wood gets dropped off all year long. 

Why would circulation alone of the OWF not be good enough to have freeze protection in the shop. The temperature of that water should be maintained by the indoor shunt pump warming the outdoor stove right?

It would still want a temperature controller to run the shop OWF pump