Where to Install Circulators

Stoker Coal Boilers automatically feed the coal and have controls and pumps just like any conventions boiler. They are intended to be used as a primary heat and often have domestic hot water coils as an added bonus. They can be set up independently or in dual sytem with your existing oil/gas boiler. They can accommodate both hot water base board or steam plumbing.
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CoalisCoolxWarm
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Post Sat. Dec. 03, 2016 12:08 pm

jrv8984 wrote:Somehow I missed that the supply and return from a zone are supposed to be the 4 pipe diameters from each other, I suppose it's because it seems counterintuitive to be returning cold water to the main loop before supplying the next zone.

Question, if I have all the hots for the 4 zones 6" apart, and then immediately continue with my cold returns 6" apart, and there's never anymore than 6" between any tee, would that work?
If I understand your question, I'll answer this way just in case ;)

4 pipe diameters for the supply and return of a single zone, then a larger distance of some sort between that "set" and the next "set" of supply and return tees for another zone.

Does that help?

FYI. Counterintuitive? Maybe. It leverages the idea of zoning, in which different zones will likely have different call for heat cycles. Even when neighboring zones are calling for heat at the same time, you run 1" zones (like I do), then you are returning 1" of 20F cooler water (ideally) from that zone into a constantly replenished 1.25" primary loop.

1.25" has almost double the flow of 1" and almost 4 times the flow of 3/4" so the returning water is diluted as it is reintroduced into the primary loop.

Before you go too far and because of your initial request for a 26 gpm pump, I suggest to take a look at this page and pay particular attention to the "laminar flow" section: https://highperformancehvac.com/boiler-piping-flow-pipe-sizing/

In a nutshell, water "sleeves" itself with an insulating layer at the outer edge of the cross-section. That's a good thing, helps prevent heat loss to the room. BUT...when the flow is too high, that layer can get too "thick" and stratifies the circulating water.

The big problem here is heat cannot transfer from the pipe to the radiant and the boiler can't get heat into the water at efficient rates.

You have to find the happy medium. Not too fast, not too slow ;)

This is one reason cooling systems in a vehicle MUST create turbulence, to break up this problem.

Note for the purists (you know who you are, LOL). I know this is not an exact explanation of the situation, but it does accurately depict the effects and what must be done to avoid it ;)

I've added a PDF attachment to this post that should answer a lot of questions for you, concerning BTUs in different diameters of pipe, etc. Notice that 1.5" can carry 1.8 times the BTUs that 1.25" does (pg 13). It also has some PEX stuff in it that you might find helpful.
GARN_WHS_Design_Manual.pdf
(2.31 MiB) Downloaded 2 times
I'm going to paste this one table from that page:
Pipe BTUs per hour per delta-T.png
According to the table, if you are looking for 170k, the 1.25" PEX only carries 150k at 20F delta-T (return vs supply temp, the BTUs used in your zones).

Even at 30F difference, it's only 270k BTUs. You have 300k boiler? At 0.8 * 300k = 240k, so it might handle it. I haven't figured out the flow rate, but I'm assuming the table is corrected for max flow rates of piping. You can always target a higher delta-T, but the zones *should* take care of this, with the limit being the coldest days with all the zones running. (Many of us crank up our boiler temps and warm our houses, overriding our setbacks)

Here's a chart showing the Min and Max flow rates for various piping types and diameters
827-Flow-Rate-Chart.pdf
(538.35 KiB) Downloaded 1 time
Here is a snip of the PEX chart:
Pipe type and diameter flow rates.png
According to the chart, PEX 1.25" is Min: 5.6 gpm and Max 11.2 gpm

That is another problem with the 26gpm pump you requested. But not to worry, the resources I'm giving you are for hydronic systems and a lot of the gotchas are factored into the data.

Is this all starting to make more sense now? It's not near the steep mountain that it might have seemed initially ;)

Numbers can be your friend, too :cheers:
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windyhill4.2
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Post Sat. Dec. 03, 2016 2:02 pm

One way to simplify the whole issue is....
Did you previously own & heat this house ??
If yes, what was the previous units capacity... as in how many BTU's ?
If for instance a 120k BTU oil boiler did the job...
Why do a heat loss analysis & worry & fuss ?
Look at the previous boiler,was it capable of the demand ?
Now you would have a good idea of needed future capacity. :)
David **** John14:6 Jesus saith unto him,"I am the way.the truth,and the life;no man cometh unto the father,but by me." Wise men sought for Jesus when he was born,wise men still seek Jesus today. Seek & you shall find.

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Post Sat. Dec. 03, 2016 11:04 pm

jrv8984 wrote:Somehow I missed that the supply and return from a zone are supposed to be the 4 pipe diameters from each other, I suppose it's because it seems counterintuitive to be returning cold water to the main loop before supplying the next zone.

Question, if I have all the hots for the 4 zones 6" apart, and then immediately continue with my cold returns 6" apart, and there's never anymore than 6" between any tee, would that work?
Have a read:
Rebuild My EFM 520
SLOW AND STEADY WINS THE RACE

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Rob R.
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Post Sun. Dec. 04, 2016 6:06 am

jrv8984 wrote:Somehow I missed that the supply and return from a zone are supposed to be the 4 pipe diameters from each other, I suppose it's because it seems counterintuitive to be returning cold water to the main loop before supplying the next zone.

Question, if I have all the hots for the 4 zones 6" apart, and then immediately continue with my cold returns 6" apart, and there's never anymore than 6" between any tee, would that work?
Having the supply and return tees close to one another allows flow in one pipe without causing flow in the other. This is called primary/secondary piping, and it is useful when not all zones require the same temperature water, when you don't want to shock the boiler with cold return water, and when there is a big difference in pump head between the boiler and the zones (like you have).

Also, you don't need to install all of the pairs of tees in a row. As you said, that reduces the temperature in the main loop for each successive zone. You can do something like this:
PS Diagram.JPG
This diagram was from a different project, but it shows that you can have a primary loop for the boiler, secondary loops for the zones, and each of the zones can have the same temperature water available.

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CoalisCoolxWarm
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Post Sun. Dec. 04, 2016 9:24 am

Okay, next item....

Since you are using cast iron radiators and are planning on adding more later, and I'm guessing you'll have more than one in a zone?

If so, I strongly recommend a split-tee design for your zones, with a balancing valve (ball valve) and each section (2 total per zone).

It works like this example.

You "split" the zone into 2 approximately equal sections or groups of radiant/radiators/etc. Zone and pump has 1" supply and return lines. Somewhere close and convenient to the separation point of the zone, install a 3/4" x 3/4" x1" Tee, one side going to each of the two sections and feed those radiant items with the 3/4" line.

Then on the return side after going through each radiant item, they come back together via another 3/4" x 3/4" x 1" Tee to the 1" zone return line and back to the primary loop via the closely spaced tee of the zone.

Be sure to install one of the balancing valves on each side of the split (I like the return side, but either will do) to balance the flow. Seldom is the resistance of each side perfectly even to assure even flow, so the valves help you balance it after installation. The valves typically are not touched after that, unless you need to close and service a component for some reason.

A split-tee zone is usually more effective at heating a zone as it avoids having cooler and cooler water from the beginning to the end of the zone radiant loop. Without it, your first section can get really hot water, the last gets cooler water and uneven heating ensues.

This kind of design for a zone is especially helpful for cast iron radiators. There are quite a few systems out there with one end of the zone that is cool and not very good at heating. It's a fairly easy retrofit, too.

IMHO, the design of the "heat delivery system" (ie zones and radiant devices) is paramount. If you can't deliver BTUs to the rooms you want in an efficient and effective manner, have uneven heating in that area, too much or too little radiant, etc....then sadly your "power plant" (boiler type) cannot be efficient and dollars slip away.
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CoalisCoolxWarm
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Coal Size/Type: Anthracite Buckwheat
Other Heating: Oil Boiler
Location: Western PA

Post Sun. Dec. 04, 2016 9:25 am

McGiever wrote:
jrv8984 wrote:Have a read:
Rebuild My EFM 520
Nice diagram, I'm stealing a copy of it! :cheers:
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Rob R.
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Location: Chazy, NY

Post Sun. Dec. 04, 2016 9:31 am

CoalisCoolxWarm wrote:Okay, next item....

Since you are using cast iron radiators and are planning on adding more later, and I'm guessing you'll have more than one in a zone?

If so, I strongly recommend a split-tee design for your zones, with a balancing valve (ball valve) and each section (2 total per zone).

It works like this example.

You "split" the zone into 2 approximately equal sections or groups of radiant/radiators/etc. Zone and pump has 1" supply and return lines. Somewhere close and convenient to the separation point of the zone, install a 3/4" x 3/4" x1" Tee, one side going to each of the two sections and feed those radiant items with the 3/4" line.

Then on the return side after going through each radiant item, they come back together via another 3/4" x 3/4" x 1" Tee to the 1" zone return line and back to the primary loop via the closely spaced tee of the zone.

Be sure to install one of the balancing valves on each side of the split (I like the return side, but either will do) to balance the flow. Seldom is the resistance of each side perfectly even to assure even flow, so the valves help you balance it after installation. The valves typically are not touched after that, unless you need to close and service a component for some reason.

A split-tee zone is usually more effective at heating a zone as it avoids having cooler and cooler water from the beginning to the end of the zone radiant loop. Without it, your first section can get really hot water, the last gets cooler water and uneven heating ensues.

This kind of design for a zone is especially helpful for cast iron radiators. There are quite a few systems out there with one end of the zone that is cool and not very good at heating. It's a fairly easy retrofit, too.

IMHO, the design of the "heat delivery system" (ie zones and radiant devices) is paramount. If you can't deliver BTUs to the rooms you want in an efficient and effective manner, have uneven heating in that area, too much or too little radiant, etc....then sadly your "power plant" (boiler type) cannot be efficient and dollars slip away.
none of that is a consideration if piping the radiators off a pex manifold.

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CoalisCoolxWarm
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Location: Western PA

Post Sun. Dec. 04, 2016 10:05 am

Rob R. wrote:none of that is a consideration if piping the radiators off a pex manifold.
...which is why now- before he buys all his components- is the time to consider all the options and work out the design. It's quite a bit more cost effective to evaluate, consider what-ifs, and make any changes now ;)

If the OP only has a single run of 10-15ft of radiator per zone, I wouldn't worry about it. On the other hand, if he is going to have 15-20ft on EACH side of a room in a single zone, it might warrant a revisit to the manifold idea- or an upsizing to have each zone get 1" feeds and you can still split-tee the zones with 3/4" out in the house ;)

In our case, the original design had far too little radiant (mostly baseboard) and before we had the coal boiler. The only way to get the house warm was to increase the water temp and get more BTUs out of the baseboard. They had long, series runs of monoflow tees with a single circulator in the primary loop. I didn't design this.

Once we retrofitted to remove the monoflows and zoned things off using split tees and later closely spaced tees with individual zone circulators, they delivered MUCH MORE heat.

Unfortunately, that is about the time we started the remodel and realized there was very little insulation and what there was had been poorly and ineffectively installed, with air infiltration like crazy :(

Sealing and insulation is the real winner when it comes to heating comfort and cost. After that would be zone radiants and design. Then the heat-plant.

By all means, let's continue to give this fellow good advice and help him understand the options available at each of the major points so he can choose what works best for his situation. Few of us have the "ideal" system for our situation, but that's the next phase- we help each other tweak and utilize what we have in the best way to maximize the benefits.

This site is full of so many professionals and seasoned laymen who give their time and effort constantly- without cost- to help others with their heating systems. Personally I think the variety of options and opinions are a real strength as one size does not fit all.

I read back through this entire thread last night and the cast iron radiators, with the expectation of adding more in the future, struck me as an important thing to plan for. The type of options I'm suggesting to consider likely wouldn't bat an eye at adding zones and more radiators and offer great flexibility.

Using a manifold and using uniform sized PEX in a single series run? Sure, I used that in an installation with all baseboard and just kept the size of each zone small enough to not be an issue. I'm not so sold on doing it with multiple cast iron radiators in series, though.

OP- How many radiators are you planning to have in each zone, now and in the future? (approx L x W x H)? Maybe Rob is right and a split-tee zone isn't necessary- or it may be very important, depending on the radiants
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Post Sun. Dec. 04, 2016 10:20 am

I never said anything about hooking radiators in series. The benefit of a manifold is a home run for EACH radiator.

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windyhill4.2
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Post Sun. Dec. 04, 2016 11:02 am

IMG_1295 (1).JPG
return manifold is at the top,supply with circulators is at the bottom,each gets it's own share of HOT water.
IMG_1295 (1).JPG
return manifold is at the top,supply with circulators is at the bottom,each gets it's own share of HOT water.
Rob R. wrote:I never said anything about hooking radiators in series. The benefit of a manifold is a home run for EACH radiator.
Like this ?
David **** John14:6 Jesus saith unto him,"I am the way.the truth,and the life;no man cometh unto the father,but by me." Wise men sought for Jesus when he was born,wise men still seek Jesus today. Seek & you shall find.

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windyhill4.2
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Coal Size/Type: 404-nut, 520 rice ,anthracite for both
Location: Jonestown,Pa.17038

Post Sun. Dec. 04, 2016 11:08 am

Not sure what took place that I got the pic loaded twice,i guess that means that one can get twice as much from it . :)
Nor do I understand why the pics loaded ahead of the print,but oh well. :)
David **** John14:6 Jesus saith unto him,"I am the way.the truth,and the life;no man cometh unto the father,but by me." Wise men sought for Jesus when he was born,wise men still seek Jesus today. Seek & you shall find.

jrv8984
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Post Sat. Dec. 10, 2016 10:19 pm

Well, I've been. Chest deep in 900' of muddy trenches all week. Got my water lines In for my animals, and the pex buried and spray foamed in the ground. We tried to install the new well pump, only to discover the well collapsed where the casing ends. As long as the weather holds out, having a new well drilled next week. Back to trying to figure out my heating system.

So eventually I was planning on having 3 zones. But at the moment, I will only have one zone although, I could do 2. As the house is worked on, what is currently apart of one zone will change. That's one of the reasons I'm thinking of using the radiant manifold, it will make things easier to change in the future.
The longest run in a zone will be about 40' round trip

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Post Sun. Dec. 18, 2016 10:19 pm

Trying to figure out cost effectiveness of plumbing this differently. If I use TRV's on the radiators off of a manifold, do I need variable speed circulators? If I don't use manifold's, I'm gonna need ,9-10 circulators and break the house down into more zones.

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Post Mon. Dec. 19, 2016 6:26 am

There are some clever pumps available that change speed/volume to output changes in system zones.
There are pump limlts, so over all size of system may require more than one pump/manifold to handle everything.
SLOW AND STEADY WINS THE RACE

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CoalisCoolxWarm
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Location: Western PA

Post Mon. Dec. 19, 2016 7:10 am

Without knowing your physical layout, I don't know if this relates to your situation, but it might give you options.

At my father in law's house, we installed a NG condensing boiler system. It's an 1800's house, one of the originals in the local town, that is divided into two halves, including the basement with very thick stone walls.

We had to make a hole between the halves, through which we ran water, electricity, and heat.

So we put a distribution manifold (similar to mine) near his boiler in one half and ran the 1-1/4" primary zone through the hole to the other half, where we placed a second distribution manifold to supply the other half of the house zones.

A really big question when deciding on how much to separate into zones is how different are the zone heating requirements and schedules?

If you are heating a commercial building, for example, where mostly ALL the building requires heat during the same hours of the day, with minor variations due to heat load, your primary need is distribution, not separate zoning of temps and times.

In most residential systems, though, you have distinct and diverse heating needs in a zone. Bedrooms get heat at night, bathrooms in the early am, various living spaces to accommodate work and occupation schedules. These do well with zoning.

Even then, zones can be grouped together if necessary. Bedrooms can be supplied at the same time, etc. As long as you can get the BTUs delivered efficiently, you can use a combination of a circulator pump for the zone with parallel radiators that use TRVs and even combine that with a split-tee design to keep the supply temps more even and stable. It really depends on what you need at your house.

Why bother zoning? Many fuel dollars can be saved and comfort can be improved with proper zoning.

Increased cost? Yes, usually. But if you're doing the work yourself, substantial savings can be had vs paying an installer. Professional installers usually save time and address the "gotchas" that come up in design and physical obstacles. Which is better for you depends on ... you ;)

I chose to zone. I am plumbed for 12 zones here, with controls for 8. The other four are for expected future installs as time, money, and need (remodeling our house) determine. Those extra 4 zones are already stubbed out with valves on the supply and return. I don't even have to shut down the system to add a zone- which is good because cold weather is when we do most of the indoor work. Warm weather is outside work ;)

You may want to look at Taco FloPro Designer. It is free software you can download and use to design your system. It will help you determine BTU needs, supply temps, circulators, etc.

Just BE SURE TO SCAN IT after installing. It contains a file that uses an often-abused exploit for its updates. Antivirus programs will complain. Turn your AV off to download and install, then turn it on and let it remove that single file. I have reported this to Taco, but never heard if they fixed it. After removing the file, you only lose the automatic update feature that I don't think is really used anyways.

If you want to do a detailed layout of your house and/or proposed system, there are plenty of smart fellers here who are quite happy to review it and point out options, gotchas, and alternatives.

Don't think you have to imitate any particular system or use all the technologies or options available. I don't think anyone here has the exact same system as anyone else. LOL.

In the end, it is all up to you.
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