Help in correcting a 1999 Gravity to circulator hot water heat system

PederFedde

I have a 1919 home that was originally gravity hot water (it had a Honeywell heat generator.) The boiler was replaced in 1999 with a Burnham low pressure boiler model # 208NS-TEI5 and no manual) and plumbed wrong. I would like to keep the boiler and do primary secondary pumping with a DHW storage tank.

I purchased a Bell & Gossett 1/12 HP Series 100 NFI Circulator (based upon the information from "Classics Hydronics") thinking that I would not do primary secondary pumping. However I am thinking it would be better. My system has three runs throughout the home with 3-1/2" and 3" pipes. I am planning 1-1/2" galvanized around the furnace connecting to the larger pipes. Since the three runs are mixed throughout the home I cannot properly zone the system so am going to heat the whole home as it was originally. In my research it looks like a good choice would be to use the Tekmar outdoor reset control 260 for this application.

The 1999 install had a Taco 007 series pump still in working condition. May I use that pump for the DHW storage tank? I will then need another pump for the three branches of pipe to the home - do I use another Bell and Gossett 100NFI or do I use a different one (which one goes where if a different circulator is recommended?) I could run three separate pumps to the three sections of the home, but I don't see the need for this added expense. I will install the 30 lbs boiler pressure relieve valve, the pressure reducing valve, the NPT Dual check back flow preventer, the Low water cutoff, the Extrol Expansion Tank (14 Gallon), the air scoop with Hy-Vent....Anything I am missing...

I know it might be overkill but I have purchased stainless steel ball valves to control the supply and return sides of each branch plus I will have a temperature gauge on each as well (I enjoying seeing the difference and that will help with balancing the runs for temperature.

I greatly appreciate this forum and learning about how to make my system most comfortable and effective.

bburd

If you still have the original cast-iron radiators, your proposed expansion tank may be too small for the volume of water in that system. You will need to calculate the volume in the radiators, pipes and boiler and then select an expansion tank.

PederFedde

bburd you may be right. I chose the expansion tank based upon the BTU of the furnace (I believe) from the supply house.com website. This will be a much more expansive calculation - I have all the radiators on a spreadsheet and the length of the runs, but I don't have the runs broken down by pipe size as they gradually get smaller as they reach the end of the line....hmmm lots of work.

This morning I am now thinking it would be simpler to not do the primary secondary pumping and just do one pump - can I still use the outdoor reset control for a one pump application? Thoughts?

WMno57

Your current system has been in place for 23 years. What do you hope to gain from this project?
I'm asking because I have a 1916 gravity hot water home. I'm not pumping away, no primary secondary, and no bladder tank. It works.
If the main impetus for your project is DHW, it might make more sense to just get a dedicated water heater. Boiler protection with primary secondary would be ideal, but your boiler has 23 years of use without that.

bburd

PederFedde said:

bburd you may be right. I chose the expansion tank based upon the BTU of the furnace (I believe) from the supply house.com website. 

Those charts are probably based on fin tube radiation, which has a much smaller water content for the same BTU output as your cast iron radiators. Expansion tanks for old gravity systems are much larger.

PederFedde

WMno57 that is a good question. I purchased the home this past spring and the person I purchased the home from said that the house was a cold house and that she was afraid that the boiler was going to explode because of the banging coming from it and one month before close the boiler wouldn't turn on. I purchased the home as is and this past month decided to make the system work better.....in dismantling the system I learned 1. the 5 gallon bladder tank was full, 2. that some of the 1999 pipe connections had very tiny leaks and 3. that the pressure valve had gone off several times. I chose to tackle it now vs wait - - in hind site I might have just gotten it going and tackled it next spring - but I didn't so now I do the work. But planning is much more difficult than I thought it would be - and the most important..

WMno57

OK, that gives us a little better idea of what is happening.
How soon do you need heat?
I suggest you do this project in phases.
Phase 1 is to replace the failed bladder tank. @bburd is right, you need a much larger bladder tank than 5 gallons. The 14 is probably too small as well, but you may want to throw it on there so you can see what needs to be addressed in Phase two.
Going to be simpler to get an electric resistance or electric heat pump water heater for DHW. I'm not an environmentalist, just trying to help you get caught up on your home projects.

leonz

Will you reconsider using gravity hot water heat for the home again since it is so simple to use and own??

WMno57

@leonz The corroded inner surfaces of those large 100 year old pipes will restrict the flow. Most of these systems had pumps added to them 70 years ago. The open to the atmosphere tank in the attic can puke rusty water onto the roof. If you want to build one of these systems in your home, more power to you. I don't think we should be recommending non pumped gravity systems though.
Pumped on the return with an air over water tank does work, and is a good solution for SOME people. If a working system currently has an air over water tank in the basement joist bays, it shouldn't automatically be swapped out, just because that's all the hydronic tech knows.

PederFedde

Thank you so much for the ideas and thoughts. 

Unfortunately I have already removed all the plumbing that was done in the 1999 work - I now know it was a foolish thing to do. So right now I have NO heat (the house is empty and in a complete restoration phase.) I have two electric heaters going to keep it manageable. 

Yes, I would consider going back to gravity as my pipes look very very clean inside. Yes there are some bumps along the inside of the pipe but very open. That is near the boiler - I don’t know how they look near the radiators. Are new gravity boilers available? PS:I have an original Honeywell heat generator that I might could use if I did go back to gravity. ???

I purchased a bunch of Ward galvanized fittings and was going to re-pipe with galvanized but now I am learning black pipe might be better or at least equal. I like the look of black better so would prefer it. I don’t want to do copper - just my preference. This is a historic restoration that I want to make appear as original as possible with modern updates. 

I will figure out my water capacity today. And the heat loss calc might be a bit more challenging. 

Clarification - the bladder tank that was installed in 1999 was attached in the piping next to the pressure relief valve on the top of the boiler. There is no other expansion tank on the system. 

I plan to have all my radiators cleaned/paint removed and reconditioned. Living in CO I don’t know if a place close that does this - so may have to take them or ship them somewhere: any recommendations? With that in mind should I remove them now and have them reconditioned over the winter or do it next summer leaving the system empty and allowing the house to sit idol during the winter but freeze protected?

I appreciate your assistance-I got myself into it and with your help I will get myself out. Ha I enjoy the process and am very handy which can be my challenge. I also like to do things the best way possible and not just settle. 

Thank you thank you for helping me feel a bit less overwhelmed. 

Jamie Hall

Somewhat miscellaneous thoughts.

First, piping. Galvanized really isn't a good choice, as -- oddly -- it tends to corrode much more rapidly and severely than black iron. However, it isn't the only choice. PEX can also be used, at least for some of the work, and in a restoration may be easier to manage for getting to the upper floors. Plan first, though, and then get your supplies...

You can go back to gravity. However, it may be better and perhaps easier to use the same radiators, provided they don't leak, and repipe the system to use a smaller modern boiler and pipe and control the system as a primary/secondary system. This has the advantage that it will be much easier for modern HVAC contractors and plumbers to understand and work on. The change isn't hard to do, starting from square one. First, you can use the existing risers and piping, to the extent that they don't leak of course, but arrange the basement piping so that they return to individual, or at least room or area grouped, ports on a manifold with balancing and shutoff valves for each group. This way you can balance the system for pumped circulation, which behaves very differently from gravity circulation.

If you need to repipe, step back a bit and consider what improvements, if any, you can make in heat loss. Then consider what temperature you will need to run the existing (or replacement, if you find damage) radiators to handle that heat loss. You may find that you can run low enough temperatures to make using PEX (oxygen barrier!) feasible and, if so, it is much easier to run a PEX line up through an existing chase than to run hard pipe. On the other hand, of course, if the existing risers don't leak there is no need to do that.

I really can't comment on modern boilers for gravity systems; hopefully someone who is familiar with what is available can. It seems to me that most modern boilers are a bit short on water volume to be satisfactory, but as I say it's not my area of expertise

Do not skimp on the expansion tank volume. This is one area where a bigger tank won't hurt anything. The original system had ample expansion volume and could keep the pressure variation within very narrow limits -- at most a pound more or less. You can do that with a modern expansion tank, but it will need to be generously sized.

PederFedde

Clarifications and additional information:

1. I am keeping the original cast iron radiators (desiring to get them refurbished),

2. I am keeping all the original 3-1/2" & 3" piping runs/returns from the boiler area to the final radiators,

3. There are three separate runs/returns from the boiler area to various parts of the home (all intermixed) and not zone possible, i.e. the living room is heated from two different run/return pipes.

4. I have six stainless steel ball valves that I will install in the furnace room to control the flow to each of the three run/returns. I am putting one on the supply and one on the return so that I can isolate them in the future if need be and balance them as needed.

5. I am returning the galvanized - and will use black pipe to connect the boiler to the three separate run/returns.

6. Yes - thank you, I am ahead of myself with the dismantle but taking the time now to plan properly for the re-install.

Finally, I am still uncertain on primary/secondary pump system if I heat the whole home and do not have zones. primary secondary requires two pumps - presumably the same size pump which is more expense now and in the future.

WMno57

PederFedde said:

I plan to have all my radiators cleaned/paint removed and reconditioned. Living in CO I don’t know if a place close that does this - so may have to take them or ship them somewhere: any recommendations? With that in mind should I remove them now and have them reconditioned over the winter or do it next summer leaving the system empty and allowing the house to sit idol during the winter but freeze protected?

My thoughts:
Not good having boilers and radiators sitting around open to the atmosphere.
You should verify the radiators don't leak before having them refinished.
Therefore my suggestion would be to do whatever is most expedient to get the system up and running now, then get the radiators refinished next summer. Your boiler can be shut down (but closed and full of de-oxygenated water) all summer. As Jamie said, black steel pipe is preferred over galvanized. Copper or oxygen barrier PEX are also fine. Don't overthink this. Perfect is the enemy of good enough. You can always make changes later.

hot_rod

I would also add a good dirt/magnetic filter into the system. Keep any rust and crud from the boiler.

You can also manifold multiple #30 tanks together. it may be less $$ than a large tank. Still go with the pro series.

leonz

PederFedde said:

Thank you so much for the ideas and thoughts. 

Unfortunately I have already removed all the plumbing that was done in the 1999 work.

I now know it was a foolish thing to do. So right now I have NO heat (the house is empty and in a complete restoration phase.)

I have two electric heaters going to keep it manageable. 

Yes, I would consider going back to gravity as my pipes look very very clean inside.

Yes there are some bumps along the inside of the pipe but very open. That is near the boiler - I don’t know how they look near the radiators. Are new gravity boilers available?-


PS:I have an original Honeywell heat generator that I might could use if I did go back to gravity. ???

(I would not use the heat generator as it still has mercury in it)

I purchased a bunch of Ward galvanized fittings and was going to re-pipe with galvanized but now I am learning black pipe might be better or at least equal. I like the look of black better so would prefer it. I don’t want to do copper - just my preference.

This is a historic restoration that I want to make appear as original as possible with modern updates. 

I will figure out my water capacity today. And the heat loss calc might be a bit more challenging. 

Clarification - the bladder tank that was installed in 1999 was attached in the piping next to the pressure relief valve on the top of the boiler.

There is no other expansion tank on the system. 

I plan to have all my radiators cleaned/paint removed and reconditioned. Living in CO I don’t know if a place close that does this - so may have to take them or ship them somewhere: any recommendations?
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(You would have to invest in a new open to air expansion tank and decide if you want to vent through the roof or pipe the overflow drain to a basement drain or laundry sink.
Lets move further along before you get that far as there are 2 ways to do this with either a saddle tank that is insulated and hung in the roof rafters or a vertical open to air expansion tank with a pipe and vent through the roof that has a screened vent that drains to a rain gutter OR a vertical tank that rests on planks and is plumbed to allow the water in the riser to heat the rank and drop back into the heating loop through a series of tee's, pipe nipples and elbows.
This tank like the saddle tank could be refilled in the basement filling the hot water riser and checking to see if the water is draining on the roof.
Now you could also run the drain line from the tank at correct tapping height in the tank to the basement to use that for the overflow when needed and let it drain to a floor drain or a laundry sink.
If the attic is insulated all the better but until you decide whether you can use a large saddle tank that is either insulated or uninsulated or a vertical open to air expansion tank with the riser pipe that warms the tank with an elbow connection and a tee in the base of the tank to let the hot water rise in the tank you need to get further along with the plumbing
Any place that does sandblasting and painting or dry ice sand blasting and painting could do the work for you as long as the radiator tapping's are plugged and the manual vents are protected if it has them.)
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With that in mind should I remove them now and have them reconditioned over the winter or do it next summer leaving the system empty and allowing the house to sit idol during the winter but freeze protected?

I appreciate your assistance-I got myself into it and with your help I will get myself out. Ha I enjoy the process and am very handy which can be my challenge. I also like to do things the best way possible and not just settle. 

Thank you thank you for helping me feel a bit less overwhelmed. 

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(I would like you to purchase a copy of Mr. Holohans excellent book on old heating systems. His book is titled "CLASSIC HYDRONICS" and describes gravity hot water systems and how they work.
You can purchase his book via the Heating Help Bookstore with a credit card and they ship the books directly to you.
This book is wire bound and will allow you to open each page and set the book down as you work or look at your existing heating system.

About a heat loss study Mr. Holohan has a method where he measures the homes dimensions, and the number of windows and doors, I dont remember if it is described in his book PUMPING AWAY OR CLASSIC HYDRONICS or both of them.

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As the newer boilers have less water volume one way to increase the total water volume for the boiler would be to use a large steel tank under system pressure(<15 PSIG) to store all the water coming from the drop pipes in your system where the header pipe from the drop pipe returns would come to the common header pipe and then the tank would be piped to the boiler sump and in the process give your boiler a huge amount of thermal mass to your advantage.

PederFedde

This is just so challenging.

leonz: If I do try to go back to gravity - that is another complication as well. I am not sure about tying in a steel tank - and then the expansion tank. where does one get an expansion tank like that and for that matter a steel tank to attach to the furnace for more mass. I have three supply pipes that warm the house (with three return pipes) and they would have to be individually connected and not piped together I would think to make it work.

Also - my original expansion tank (not in existence) was in a second floor closet next to the laundry chute and it was vented into the attic and then into the sewer air vent - so nothing was ever going "outside". What is unknown is that there were two pipes going to the expansion tank - one is capped off and I haven't discovered where it comes from - perhaps to one of the supply lines upstairs..The other one comes from the basement and was attached to the Honeywell heat generator (which is still there)

I put together the amount of pipe and radiators in my home and now I don't know where to find a correlation to the size of the bladder tanks....Most of what I found is all based off of BTU.

In my heat loss calculation it appears that my current boiler is very near the target point. If I do some insulating that will change that, but also plan to expand some also in the future.

I have all three books recommended and they are very good...unfortunately I don't have the "classic hydronic" book here with me - so I just ordered another...

leonz

Hello PedeFedde,

Let's all collectively get your heat fixed and worry about adding thermal mass later with a new tank if needed.

If you use a circulator you have the option of using a steel compression tank or an expansion tank to create the point of no pressure change.

A gravity hot water heating system has the advantage of not having anything in it except the boiler, a riser pipe for hot water to reach the radiators all the way to the top floor, drop pipes from each radiator that are either tied together with a radiator on the upper floor or separately that have return pipes to the return header pipe connected to the boiler sump to be reheated.

The Honeywell Heat Generator was created by Mr. Honeywell to make hot water heat faster to compete with steam heat if I remember my reading of its history correctly.

I don't know if a Honeywell heat generator would allowed legally or comply with the plumbing code due to its reservoir of mercury as it is a toxic heavy metal that it is dangerous unless it is properly handled.

Can you tolerate paying a licensed steam plumber for 2 hours to come and look at your current heating system as is??

Lunch and a beer or dinner would help smooth things along and allow you to establish a relationship with a
steam heat based plumbing firm.

Once the steam licensed plumber looks at your entire homes heating layout which was designed to use the Honeywell Heat Generator to provide heat quickly to your home when it was built will provide the steam licensed plumber with the needed view of things to help you.

You just might be able to use an open to air expansion tank with a float switch in the vertical tank to
push water up to the second floor and into the tank and let gravity do the rest and provide you with slow comfortable even heat that will heat everything in your home right to the basement at a lower temperature.

Don't be afraid of carrying around your copies of CLASSIC HYDRONICS and HOW COME to lunch or dinner with your steam licensed plumber and carrying it around in the basement while you do your walk through with the plumber as you will be able to ask questions and also show the examples that Mr. Holohan has written about in plain English to allow you to have a well versed discussion with your steam plumber.

Please don't fret and worry, there are many HH members that know much more about heating than I do that will be able to help you right down to the last pipe hanger in your heating system.

You already have a simple heating system and all it needs is some TLC and some proper plumbing to bring it back to good shape to have gravity heat again.

Robert_25

PederFedde said:

Clarifications and additional information:

1. I am keeping the original cast iron radiators (desiring to get them refurbished),

2. I am keeping all the original 3-1/2" & 3" piping runs/returns from the boiler area to the final radiators,

3. There are three separate runs/returns from the boiler area to various parts of the home (all intermixed) and not zone possible, i.e. the living room is heated from two different run/return pipes.

4. I have six stainless steel ball valves that I will install in the furnace room to control the flow to each of the three run/returns. I am putting one on the supply and one on the return so that I can isolate them in the future if need be and balance them as needed.

5. I am returning the galvanized - and will use black pipe to connect the boiler to the three separate run/returns.

6. Yes - thank you, I am ahead of myself with the dismantle but taking the time now to plan properly for the re-install.

Finally, I am still uncertain on primary/secondary pump system if I heat the whole home and do not have zones. primary secondary requires two pumps - presumably the same size pump which is more expense now and in the future.

Hello. How many radiators are there in total? Can you post a rough sketch of the piping layout?

Hang on to the B&G Series 100, it might be perfect for the secondary piping.

Here is a video to give you an idea of how an old gravity system can be converted to primary/secondary piping: https://heatinghelp.com/systems-help-center/converting-from-gravity-to-pumped-flow/

leonz

He needs a plumber first before he spends any more money.

Robert_25

The better educated you are before calling someone the more likely you are to end up with a competent contractor and a system that meets your expectations. There is no sense in paying professional rates for hack work.

If the OP is looking to hire this out I suggest using the "find a contractor" tool: https://www.heatinghelp.com/find-a-contractor/

Robert_25

PederFedde said:

Clarifications and additional information:

Finally, I am still uncertain on primary/secondary pump system if I heat the whole home and do not have zones. primary secondary requires two pumps - presumably the same size pump which is more expense now and in the future.

The primary circulator may not need to provide nearly as much flow as the secondary. In many situations a Taco 007 or something similar is fine.

PederFedde

Robert_25: Common sense to me says that the primary circulator should circulate at least the same amount as the secondary pump.. Where does the larger secondary pump get its water??? I also don't understand how the B & G 100 can have a 0-33 gpm water flow... It isn't variable speed that I know of...

Based upon the chart that you referred to (which I have looked at previously) The closest plumber to my location is Kansas City which is ~10 hours away (~575 miles.)

Thank you for this comment and support - this is a very true statement: "The better educated you are before calling someone the more likely you are to end up with a competent contractor and a system that meets your expectations. There is no sense in paying professional rates for hack work."


leonz Yes, I would allow and pay for a steam plumber to come look at the home, but I don't know of any. Isn't steam different than gravity Hot water though?

I have been laden with a cold which has dampened my spirits, but I am doing better and thinking more clearly now.

The idea of keeping my 1999 boiler and doing a p/s circulator may be the answer for now to get the system up and running and then look into getting the home restored back to a gravity system in the near future when I finish the restoration - adding back radiators that were disconnected/discarded and clean the existing radiators replacing valves etc. Also, finding a gravity boiler doesn't appear to be a very simple task as nobody does this anymore and for the ones that I looked at that might work for my BTU need only have 1-1/2 connections

PederFedde

This is the pipe layout of the boiler pipes in the basement and where they go

PederFedde

These are my existing and potential radiators

PederFedde

This is my pipe chart with radiators in the different runs and the total linear feet of pipe in the run.

Robert_25

PederFedde said:

Robert_25: Common sense to me says that the primary circulator should circulate at least the same amount as the secondary pump.. Where does the larger secondary pump get its water??? I also don't understand how the B & G 100 can have a 0-33 gpm water flow... It isn't variable speed that I know of...

In many cases the primary loop does have more flow than each secondary circuit, but in your situation you have huge piping that requires a certain flow rate to get even heat distribution among the radiators. The flow rate through the boiler only needs to move enough BTUs to heat the house. Do you have a rough idea of what the heat load is? I know you have determined how much the radiation can put out, but many old homes are over radiated.

The B&G Series 100 (like most circulators) has a flow rate that varies with the amount of resistance in the piping circuit. With a large amount of resistance (called pump head) there will be little/no flow, and with no resistance it will pump about 33 gpm. With 3" piping your system will have very little resistance, so the series 100 will be at the far end of its pump curve.

As for where the pumps get water - once you have purged the system of air you are just circulating the same water through a given circuit. With the right piping techniques the flow in one circuit won't influence the flow in another.

PC7060

A very small pump will probably suffice.  I updated a previously converted gravity system to a pumping away configuration running a low temp profile (90-120F based on OWT).  I used two Extrol 30 versus one larger tank; cheaper and provides a level of redundancy.  

One zone with a Grundfos Alpha 2 circulator running a lowest constant speed setting. At temp it moves 8GPM using 8 watt power. 

Re the heat loss calculations, I had Mestek do the calculations.  Cost was pretty reasonable and my AHJ required 3rd party PE signature. 

leonz

PederFedde said:

Robert_25: Common sense to me says that the primary circulator should circulate at least the same amount as the secondary pump.. Where does the larger secondary pump get its water??? I also don't understand how the B & G 100 can have a 0-33 gpm water flow... It isn't variable speed that I know of...

Based upon the chart that you referred to (which I have looked at previously) The closest plumber to my location is Kansas City which is ~10 hours away (~575 miles.)

Thank you for this comment and support - this is a very true statement: "The better educated you are before calling someone the more likely you are to end up with a competent contractor and a system that meets your expectations. There is no sense in paying professional rates for hack work."

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leonz Yes, I would allow and pay for a steam plumber to come look at the home, but I don't know of any. Isn't steam different than gravity Hot water though?

I have been laden with a cold which has dampened my spirits, but I am doing better and thinking more clearly now.

The idea of keeping my 1999 boiler and doing a p/s circulator may be the answer for now to get the system up and running and then look into getting the home restored back to a gravity system in the near future when I finish the restoration - adding back radiators that were disconnected/discarded and clean the existing radiators replacing valves etc. Also, finding a gravity boiler doesn't appear to be a very simple task as nobody does this anymore and for the ones that I looked at that might work for my BTU need only have 1-1/2 connections

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Don't fret about your boiler, it is not that old yet and all you may need is to have the proper plumbed lines and a small expansion tank to aid in making and using it for a gravity hot water boiler.

Basically in heating methods the only real difference is you are using gravity with either a wet steam or dry steam form of heating versus lower temperature liquid water for a heating method.

I recommended that you talk to a steam, plumber for the simple reason that (1) HEAT RISES in a both a steam heating system as well as a gravity hot water heating system by heating water with combustion,
remember this every time you here a steam kettle whistle.

(2) a steam licensed plumber will know what he or she is looking at with your entire system, your drawings, and your existing pipe schedule and potential pipe schedules layout and will tell you what will work before you do it.

All you need to do is contact your local building and plumbing inspector and ask who and how many steam licensed plumbers there are in your county or close by as you need to have a consultation with one.

PederFedde

One big question:
I have been referring the the primary as the pump circulating the water around the boiler and secondary as the one pumping to the home. This is wrong as I seriously studied the pictures. primary serves the home and secondary serves the boiler......
https://heatinghelp.com/assets/Uploads/heating-p28-300x206.gif


HOWEVER - it appears that now in many cases I see the primary as that serving the boiler and secondary as that serving the house....when I researched the magnetic dirt filter that appeared to be the case on their drawing.....

SO to clarify my application: the B&G which is larger would be pumping the water throughout the house while the smaller taco 007 would be circulating the water through the boiler..... is this correct?

Assuming this is correct - how does the 33gpm get supplied if the taco is pumping 23gpm does the other 10pgm come from the return and thus lowering the supply temperature to the home?

hot_rod

Defining which loop is which is complicated. Most agree the loop that has the expansion tank connected is the primary loop. It could be either loop.

Sometimes easier to say boiler loop and distribution loop.

So both loops need tom have a circulator sized just for that specific loop. Could be one is larger thja the other.

With large diameter piping and cast radiators, that should not require too large of a pump. A small multi speed wet rotor is nice so you have some adjustability.

With a cast iron boiler, no need to have primary secondary. I would like to see a boiler return protection device however.

It really could be this simple.

PC7060

“ Sometimes easier to say boiler loop and distribution loop.”

Good advice @hot_rod

PC7060

@PederFedde - do you want to keep
the B&G circulator?  

What temperature is the boiler aquastat set at? 

If at 160F or higher the system is likely circulate fine without a pump. Problems would arise with overheating unless you had TRV on the radiators. 

PederFedde

PC7060 - I purchased the B & G Based upon the recommendation in the "Classics Hydronic" book...I would have to return it to Supply House if I didn't keep it. If it will be the best pump then I am ok to keep it - if there is something new and better than when the advice was given then I am open. I do know it has to have low head and not high rpm. (at least that is what I have read and understand)

I have vacillated back and forth between P/S pumping and just running one pump and keep it simple as you diagramed..Then there is the desire to bring it back to gravity - but I think that might be later... I do not have the valves that you pictured but I have read about them. If I do those it would also be later when I take out the radiators for cleaning and sprucing up.

The boiler is set at 180degrees

hot_rod

So you do have TRV controls? Is so and ECM style circ with a delta P mode would be ideal. That is exactly what the pumping logic was designed for , TRV systems.

Keep in mind Classic Hydronics was written well before ECM became mainstream.

This schematic happens to show zoned fin tube, but the same would apply for radiators "zoned" by TRVs as far as the logic.

PC7060

I went through a lot of these issues on my gravity system conversion from a 180F BG pumped system to a low temp / pumping away system using a ModCon boiler and ECM circulator. I’ve attached a link to the thread below if your interested. 

https://forum.heatinghelp.com/discussion/179973/design-updates-for-modcon-boiler-in-100-year-old-high-mass-gravity-system

PederFedde

I do not have TRV controls. Some radiators are in need of new valves as they are broken and the remainder are the original style turn valves. I can fix that in the future when I clean up and restore the radiators.

I am going to keep the 1999 Burnham boiler - my decision for now is P/S pumping or one pump with bypass.. Thank you PC7060 for the reference to your update - it was interesting and informative.

PC7060

I’d install the TRV as part of initial upgrade.  Make a huge impact to system performance and comfort. 

For what’s it’s worth, I added the TRV to my rads a couple years before I had the rads sandblasted snd powder coated. Also movers are your friend when moving radiators / transporting radiators.  

hot_rod

You can replace the operator on a TRV like this, if that is what is broken? The TRV will gently modulate the temperature in the room. Worth repairing or upgrading.