# Had boiler installed, doesn't work correctly! Please Help



## IACG (Mar 2, 2015)

Hi,

I just installed an indoor wood boiler in my shop which will heat the shop (30'x50' w/ 14' ceiling) and has a line to the house which will heat my DHW, has a rad in the forced air furnace and is connected to my floor heat of my garage.  The garage already had floor heat which was heated with a 3000W DHW tank element.  I had a guy come out to install the system for me because I didn't want to spend a lot of money installing pumps, mixing valves etc and then have something done wrong and it not work.  Unfortunately, after the install, I found out it does not work.

First, here is the problem.  My fire goes out on me before the wood is all burnt, the water is only luke warm coming out of the boiler. It is warm enough to heat floor heat, but does not do any good for the sidearm on the hot water tank, or the rad in the furnace.  The boiler says that it gets really hot in fact it shut itself down because it hit the high temp alarm.  I realize that the water at the top of the boiler is getting hot, but the water is stratifying in the boiler.  I checked the flow and realized I do not have the minimum recommended flow.  The instructions coming from the boiler say 14 gpm min.  I have a total of 7.

With that said, I'll describe the system and include a couple of diagrams.

The shop is heated with one pump (15-59 Grundfos Pump).  There are 4 loops of 1/2" pex in the floor.  I measured 2.5 gpm on this loop.

The house is fed by one pump (26-99 Grundfos Pump).  1" pex pipe is used throughout this loop.  The distance from the boiler to the house is 170'.  Inside the house the first component in the system is a 4' sidearm on the DHWT.  Next it goes to a 20"x20" rad in the furnace.  After this it goes to the attached garage.  Here there is a ball valve installed across the Supply and Return which I was told to leave open (otherwise it forces it through the garage system.)  After this ball valve the return line goes back to the boiler.  In the garage is a mixing valve and a pump, connected through my original DHWT element boiler.  There are a lot of elbows (just over 20) in the system and the flow of this loop is 4.5 gpm.

The talked to the guy I bought the boiler from (who is not the installer, he does not install them, but recommended the guy who did the install.) and he suggested I put in a second pump in the return line at the house.  Is this a good idea?

Here are some diagrams I drew of how the system has been put together.
Edited:  I had two mistakes on my diagrams. One length was 5 3/8" instead of 36' and I drew one of the mixing valves in with it pointed the wrong way.  (Sorry to add confusion)




Any help would be greatly appreciated.
Thanks!


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## DaveBP (Mar 2, 2015)

Do you have anything on the return lines to the boiler to keep the minimum temperature going back into the boiler above a minimum temperature (something like 130 or 140F?

That is a LOT of heat to try to force through that much 1" PEX.


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## tom in maine (Mar 2, 2015)

First look, the Garage needs its own loop. It should be in parallel with the house and the shop, not in series with the house. To force the return from the house to the garage and then back to the boiler is way too much frictional loss. There should probably be a pump on the house loop as well. The house and garage would benefit from a primary/secondary plumbing design.


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## maple1 (Mar 2, 2015)

You will need to measure temps in your piping, wherever it goes in and out of something.

All over. Starting with the boiler.

I can't look at pump curves from here, but that's a long run for 1" pipe - first flag.


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## BoiledOver (Mar 2, 2015)

Begin at the boiler...............It does not get up to temp. After that is resolved, consider the zones if need be.

What boiler are you using? Name and capacity?


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## IACG (Mar 2, 2015)

DaveBP said:


> Do you have anything on the return lines to the boiler to keep the minimum temperature going back into the boiler above a minimum temperature (something like 130 or 140F?
> 
> That is a LOT of heat to try to force through that much 1" PEX.



Something to keep the return above a minimum temperature?  Sorry for my ignorance, I'm kind of new at the this, hence the reason I hired someone to do it for me.   A friend did tell me that the temperatures should not be drastically different, but what can I do to minimize this difference?  What are you suggesting?


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## IACG (Mar 2, 2015)

BoiledOver said:


> Begin at the boiler...............It does not get up to temp. After that is resolved, consider the zones if need be.
> 
> What boiler are you using? Name and capacity?



The boiler is a HeatMaster G200.  It lists a Max BTU Output of 232000 BTU/hr and a Heat Output (8 Hour Burn) of 111500 BTU/hr.  195 gallon water capacity.  From what I understand the reason it does not get up to temp is because the water is stratifying due to lack of circulation.  Therefore, the top of the boiler heats up, telling the sensor to shut down the fire.  It has a damper and a fan both of which shut off because thinks that my water storage is all hot.  I figured if I increased the gpm, with the increased flow I might solve that.


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## Mauler (Mar 2, 2015)

also check the temp sensor.


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## IACG (Mar 2, 2015)

Well, I would agree except that when it says that the boiler is hot, it really is because it starts steaming out the top, yet the supply lines are still just warm.  After running for a while they did get warmer, but still not what I would call hot.  I could hold my hand on the elbow right at the supply coming out of the boiler.  I do have a thermometer strapped to the pex just after the pump, but there is no insulation around it, so it really is not a valid measurement.  It started out at around 5 degrees Celsius and the hottest it ever went to is 36 degrees Celsius.


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## IACG (Mar 3, 2015)

I wish I had come to this forum before starting the project.  If you can give me some advice as to what can be done now, with the boiler and line to the house as is that would be great.  I laid the line to the house before pouring the shop's slab.  This set of 1" lines was what was recommended by the dealer where I bought the boiler and the pipe.  I told him what I was wanting to heat at the house and garage.  To add another line to the house right now is not really an option. (I hope)  I'm over budget on this project already.
Thanks


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## maple1 (Mar 3, 2015)

Sure sounds like not enough water moving, if the boiler is heating like I think you say. Could be a whole host of issues going on here, starting with near-boiler piping & continuing to each area. We would need all the temp data I mentioned above, plus lots of pictures. Not sure what an 'easy' fix for now would be, but it would likely involve adding another pump to the loop. Maybe a big one. Also suspect a poor choice of underground pipe.

Does the shop heat OK?


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## brant2000 (Mar 3, 2015)

That's completely unrealistic to expect to move nearly 14 GPM through 1" pex that distance.  If you just find a run a quick calculation using something like this (http://www.freecalc.com/fricfram.htm), you'll see that the head loss at that distance and flows are enormous.  I just did a quick calc at 350' of 1" (I would expect 1" steel without additional fittings to be similar to pex) at 14 GPM, and found the head loss to be 44'.  Without looking at the curve for your pump, I doubt it even dead heads at 44', let alone can push anywhere near 14 GPM at 44'. 

I second Tom's recommendation to split the garage off as a secondary, parallel loop and see if that might get you closer to minimum flow.


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## maple1 (Mar 3, 2015)

Just looked at the diagram again. So it's 170' (x2) underground - then another 100' within the house? So something like 450' of 1" pex? Plus all the fittings & mixer & heat exchangers? Pretty sure there's not much water going around that. You might be behind a big 8 ball starting with the undergound pipe. Curious as to exactly what kind of pipe it is - most of whatever heat gets out of the boiler could be going into the ground.


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## IACG (Mar 3, 2015)

maple1 said:


> Sure sounds like not enough water moving, if the boiler is heating like I think you say. Could be a whole host of issues going on here, starting with near-boiler piping & continuing to each area. We would need all the temp data I mentioned above, plus lots of pictures. Not sure what an 'easy' fix for now would be, but it would likely involve adding another pump to the loop. Maybe a big one. Also suspect a poor choice of underground pipe.
> 
> Does the shop heat OK?



The shop and the garage were heating up nicely.  My attached garage went from 6 degrees C to 15 degrees C in 2 days of running the boiler (Air temperature).  This is with the boiler having gone out on me over night and then me starting a new fire in the morning.  The shop also was warming up I have a temperature sensor in the floor and it went from 7 degrees C to 14 degrees C in that same time.

My side arm and rad were the issue because I need actual hot water coming to them, not just warm water as the floor wants (obviously normally done with the mixing valve though).

I let the fire die and have not had it running now since Saturday when I realized that the lack of flow was causing the boiler to not operate correctly.  That's when I phoned the boiler dealer and he suggested adding another pump.  I figured I should do a bit of research before just throwing another pump at it.  This is why I don't have any temp data as you suggested I should take.

Thanks for your suggestions so far.


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## IACG (Mar 3, 2015)

tom in maine said:


> First look, the Garage needs its own loop. It should be in parallel with the house and the shop, not in series with the house. To force the return from the house to the garage and then back to the boiler is way too much frictional loss. There should probably be a pump on the house loop as well. The house and garage would benefit from a primary/secondary plumbing design.



When you suggest putting the garage on its own loop, your suggesting digging in a new line toward the house/attached garage? Or are you suggesting reconfiguring the loops once they are at the house/garage?  (I hope you are because right now I can't afford to trench more stuff to the house.)


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## IACG (Mar 3, 2015)

maple1 said:


> Just looked at the diagram again. So it's 170' (x2) underground - then another 100' within the house? So something like 450' of 1" pex? Plus all the fittings & mixer & heat exchangers? Pretty sure there's not much water going around that. You might be behind a big 8 ball starting with the undergound pipe. Curious as to exactly what kind of pipe it is - most of whatever heat gets out of the boiler could be going into the ground.



The pipe is called 1" pex though it has an inside diameter around 7/8".  It has the two pipes with Styrofoam around it inside a drain-tile type pipe. (Not perforated though obviously)


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## leon (Mar 3, 2015)

The first thought that comes to mind is thermal shock.

Is this fellow a licensed plumber?

It is entirely possible the cooled return water is not mixing in 
the boiler with the hot water to then circulate the 
water completely.  

Where does the cold return water enter the boiler?
Where the heated water exit the boiler? They cannot 
enter and exit on the same side  

The cooled return water must be heated fully and then 
pumped to the shop and home.

In my case the the heated water is suctioned to the 
base and then pumped to the single heat loop and the 
temperature balancing pump between the two boilers 
I have which are a wood and coal boiler and a Buderus 
oil fired boiler.


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## Tennman (Mar 3, 2015)

Do you have an estimate of how much energy you want/need to dump into the house? If so I can plug that into a spreadsheet to compute gpm, velocity, and head based on your 1" pex which will tell you if the pump's adequate. Unless you have a very efficient home that's not too large, 1" is pretty small for those distances. Which means to move more btus/hr you must increase velocity, which increases head, which increases pump horsepower. 

Somehow get the temp of the water entering your underground and the temp where it exits to get the temperature loss in underground. I lose about 1* or less in about the same distance (2*F round trip including thru the HX when fan's off). The source of our boiler said 1" would be adequate, but I did the math and installed 1 1/4"... for our boiler which is roughly in your class, our install would be more efficient with 1 1/2". I was in similar circumstances 6 years ago and the guys here helped me sort it out.  In my case years ago it was multiple problems I needed to address. But checking pump size is a start. The diagnosis process often involves going down the list identifying what it's not.

BTW.... Did you read the underground sticky? The pipe drain I used for my first underground was not perforated, but when I sprayed foam inside I was shocked to see all the tiny pin holes. When I dug up my first underground install it was all filled with water and mud. I was losing a huge amount of energy to the dirt. Yes... too bad you discovered this site after the fact, but you'll get lots of great help here.


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## Karl_northwind (Mar 3, 2015)

it looks like you may need return protection, and probably need a primary loop on the boiler from which you pull secondary loops to the house, garage. that will keep the boiler stirred, and reduce the chances of thermal shock.  might be a good application for a taco bumblebee.  it'll ramp up when the loops start calling, but keep the boiler mixed running on low when heat loads are not calling.

for starters, I would connect the attached garage in-floor as a secondary as it is, but right after the forced air coil in the flow loop.

you're definitely hampered on the size of the underground pex.   you could for now go to a larger circulator in stead of the 2699, maybe a taco 2400-50 or so (you could also add a second 26-99 in-line and remove it if you replace or upsize the underground).  the circular alone is a bandaid solution though, you need bigger pex underground for those distances.

If I remember the operation of the G-200 right, if the boiler is at full fire and the water temp goes down too far, it will think the wood is exhausted and shut down.  the short primary loop mixing at a relatively high flow rate will help that, as well as provide some moderate return protection.

and also: Plumber does not necessarily mean knowledgeable in boilers.  

karl


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## slowzuki (Mar 3, 2015)

It sure seems to me that the house zone is pulling water from the Taco Mixing Valve, going around the boiler.  That's the only way I see how the cast iron suction feeding the house zone pump is cold while the boiler high temp is kicking on.

I think people missed the note about the T's and are taking the drawing to mean 4 connections to the boiler.  The mixing valve is drawn odd too, is this the actual valve orientation in the install?  I would expect the mixed leg discharging into the radiant load in the garage.


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## maple1 (Mar 3, 2015)

Pictures would likely help quite a bit.


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## IACG (Mar 3, 2015)

slowzuki said:


> It sure seems to me that the house zone is pulling water from the Taco Mixing Valve, going around the boiler.  That's the only way I see how the cast iron suction feeding the house zone pump is cold while the boiler high temp is kicking on.
> 
> I think people missed the note about the T's and are taking the drawing to mean 4 connections to the boiler.  The mixing valve is drawn odd too, is this the actual valve orientation in the install?  I would expect the mixed leg discharging into the radiant load in the garage.



I'm going to take a look at the orientation of the mixing valve.  Likely I just drew it wrong.  Looking at the diagram I put a comment on there saying that the back-up electric heat source in the attached garage is not going to work the way it is shown there.  Maybe I just drew it wrong.  I also noticed a mistake on my measurements diagram.  The distance from the garage to the exit of the pipe from the house is not 5 3/8"... I messed up and did not type in the right size.  That one measurement is the actual size of the drawing.  Sorry for the confusion.


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## IACG (Mar 3, 2015)

Here are some pictures of what I've got:




(Above: This is at the switch over from 170' coming from shop into the house.  The Ts and valves were for the addition of a small floor heat loop in the future.  (yeah right!))


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## maple1 (Mar 3, 2015)

I would be nervous having my near-boiler piping in pex like that, would feel much better with copper or black iron. And not 100% sure from the pic, but that looks like the kind of underground piping that might end up sending a lot of your heat into the ground eventually - are both lines together in the same cavity?

Is this a pressurized boiler/system?


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## Smoke Signals (Mar 3, 2015)

first thing I see is in pic #3, there is a by pass valve open. I will look a more.

edit: ok, after looking at the drawing I see why the by bass is open.


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## Smoke Signals (Mar 3, 2015)

Can you post a pic of the side arm?


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## Smoke Signals (Mar 3, 2015)

What is the cord hanging down in pic #4, that's not for the circulator is it?


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## slowzuki (Mar 3, 2015)

Thanks for pics, helps a lot, I was mistaken about the connections.

Ok so lots of people are hung up on the details of the piping runs and flows but there is a more basic problem, we can't be getting boiling and high temp shut down while having cool/barely warm to the touch water coming out the supply connections.  The fire tubes are hottest at the bottom of this boilers tank so it can't stratify while being fired even with no loads/flow.

You have no return protection for the boiler and both loads are leaving slabs so you can be dumping very very cold water straight back into the boiler not a short term problem for a gassifier type boiler but a longer term issue for lifespan.  Ignore for now.

At the flows you mention in the loops in parallel, you can't have boiling in a 110 kBtu boiler while dumping almost 7.5 gpm of 15 C slab return water into the top of the tank unless your boiler is low on water.  The heating load is just so much larger than the boiler output it can't boil it.

As an example, if you are boiling at 212 F and getting 60 F water back from the slabs, at about 7.5 gpm combined flow, you need 570 kBtu input to keep water temp up, 5 times the rated output of your boiler, you'll never keep the water temps up to that 212 F.

Your cold slabs both continuously calling for heat should be overwhelming your boiler in the current config.  Improving flow in the feed to the house right now will just expose the boiler to more load until that slab starts coming up to temp.


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## heaterman (Mar 3, 2015)

Look at the "sticky" up at the top of the boiler forum here titled primary secondary .......

Doing that for the garage indoors and adding a dedicated circulator for that area will help the flow situation a bunch. 
Right now when your garage zone is calling for heat, all the flow in that loop is diverted through the floor along with everything else. I'd guess you're less than 2gpm at that point.  Running the garage as a secondary off the main loop would be relatively easy to do and not overly expensive  

You don't have many good options given the loop configuration and the 1" pex  
That loop really needed 1-1/4" in the first place.​


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## heaterman (Mar 3, 2015)

"Plumber does not necessarily mean knowledgeable in boilers."
karl[/quote]


Sad to say but what Karl said there is true in a great majority of installs. Licensed or not.
I'd say the percentage of installation we encounter which are just plain bad is close to 80%.  I swear most OWB installers, and dealers for that matter truly believe there is no reason  for anythinglarger than. 1" tube. They seem to have the notion they are in some kind of magic zone where the laws of physics do not apply.

Here's the tell on your installation.....
Ask the dealer, and then the installer to calculate the head in that house/garage loop. I'll wager you get a deer in the headlights look. 

Btw, I believe Karl is right about the automatic shutdown on your boiler if the water temp fails to rise. It thinks the fuel is gone because it sees no temp increase and shuts off the fan.

So.
1. You need a boiler protection device to keep boiler temp at 130-140.  That's going to mean not allowing all loads on at the same time so additional controls will be required.
2. Separate the garage loop as a secondary circuit off the main 1" going to the house.
3. As Slowzuki said, if all your zones are calling, there is no way the boiler is large enough to service that load. (Refer to item 1)


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## IACG (Mar 4, 2015)

slowzuki said:


> It sure seems to me that the house zone is pulling water from the Taco Mixing Valve, going around the boiler.  That's the only way I see how the cast iron suction feeding the house zone pump is cold while the boiler high temp is kicking on.
> 
> I think people missed the note about the T's and are taking the drawing to mean 4 connections to the boiler.  The mixing valve is drawn odd too, is this the actual valve orientation in the install?  I would expect the mixed leg discharging into the radiant load in the garage.



Thanks for pointing out my mistake on the schematic.  I drew the valve in the wrong direction.  I've updated the schematic on the post above.

There are 4 connections to the boiler.  I have pictures up now to make sure everyone understands.


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## IACG (Mar 4, 2015)

maple1 said:


> I would be nervous having my near-boiler piping in pex like that, would feel much better with copper or black iron. And not 100% sure from the pic, but that looks like the kind of underground piping that might end up sending a lot of your heat into the ground eventually - are both lines together in the same cavity?
> 
> Is this a pressurized boiler/system?



Not pressurized.


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## IACG (Mar 4, 2015)

Smoke Signals said:


> Can you post a pic of the side arm?



In the picture I have the valve above the tank shut so that I'm not cooling the water in the tank.  The pump was circulating cool water.


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## IACG (Mar 4, 2015)

Smoke Signals said:


> What is the cord hanging down in pic #4, that's not for the circulator is it?



The pumps were wired in temporarily by the installer.  I was going to get them done correctly yet, but I'm holding off now until I know how many pumps I will actually need.


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## slowzuki (Mar 4, 2015)

I'm just gonna pick on a couple of things:

RE 1. - return protection for boiler doesn't mean you have to manage loads, but managing loads certainly helps your control and comfort.
RE 2. - The house garage loop is a secondary circuit.  The bypass acts like close spaced T's.  The 1/2" pex in slab will only have very very small induced flow while main loop operating as is plumbed UNLESS the bypass is closed.  I'm assuming the bypass valve is there to aid in purging the pex in the floor.
RE 3. - Sometimes when bringing slabs into service after being unheated, you just have to wait.  If you have return protection you can maintain limited service of other loads or assign priority to the house loads which is what heaterman is talking about in 1.  If you don't have return protection, load priority won't matter.

General comments:
Folks are picking on the 1" loop and yes its not ideal especially with all those fittings BUT if the boiler side of things is set up right, you are sending water to loads in the right sequence with the load requiring lowest water temp last.  Because this generates a large delta T, a lot more BTU's can be moved for a given GPM going to the house than what some folks systems can do designed using a low delta T.  Doesn't cause the main problem with the boiler.



heaterman said:


> "Plumber does not necessarily mean knowledgeable in boilers."
> karl


Here's the tell on your installation.....
Ask the dealer, and then the installer to calculate the head in that house/garage loop. I'll wager you get a deer in the headlights look.

Btw, I believe Karl is right about the automatic shutdown on your boiler if the water temp fails to rise. It thinks the fuel is gone because it sees no temp increase and shuts off the fan.

So.
1. You need a boiler protection device to keep boiler temp at 130-140.  That's going to mean not allowing all loads on at the same time so additional controls will be required.
2. Separate the garage loop as a secondary circuit off the main 1" going to the house.
3. As Slowzuki said, if all your zones are calling, there is no way the boiler is large enough to service that load. (Refer to item 1)[/quote]


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## brant2000 (Mar 4, 2015)

IACG said:


> In the picture I have the valve above the tank shut so that I'm not cooling the water in the tank.  The pump was circulating cool water.



Wow, that's a big sidearm.  I heat mine with a very small sidearm that's about 16" long.  I also didn't notice at first, but you really shouldn't have your sidearm and HX in series (or if you did, you would probably want them in reverse order).  It may be one of the lower items on the list of things that need modified, but that's something else to consider.


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## James Reimer (Mar 4, 2015)

Speaking to a troubleshooting rep for Heatmaster, the G200 is very sensitive to supply/return flow rates.  Apparently there are baffles and manifolds inside the boiler that direct cold water to certain places.  If the flows are not at least 14 GPM there is a stratification issue inside the boiler and the supply water will never get hot while the top of the boiler will boil over.  Having low flow and a high delta T like this scenario is, it will only exacerbate the problem as the cold water will fall to the bottom of the boiler and cause extreme stratification.

In typical boiler designs with storage stratification is your friend, but in this model of boiler the supply and return are located closer together in the middle of the water jacket. This is a unique situation for this model of boiler that doesn't happen to other manufacturers that have the supply at the top and the return at the bottom. 

To resolve the issue he needs to get the flow rates up with a secondary mixing pump, or make some plumbing adjustments and add another pump for higher flow rates.


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## maple1 (Mar 4, 2015)

Sounds like you need a boiler bypass loop - which should also be able to be set up/controlled to provide boiler protection. Which I guess is what the 'secondary mixing pump' is. Also sounds like a unique boiler design - interesting.


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## brant2000 (Mar 5, 2015)

James Reimer said:


> This is a unique situation for this model of boiler that doesn't happen to other manufacturers that have the supply at the top and the return at the bottom.



Forgive me if this sounds ignorant, I have no knowledge of Heatmaster or this particular boiler, but this is a basic tenant of thermodynamic design.  There's a very good reason that coolant always flows through a car engine from bottom to top, and opposite through the radiator.  This sounds like a very poor design.


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## Karl_northwind (Mar 5, 2015)

it uses the principal of a counterflow heat exchanger, which is basic thermodynamic design.  the return top supply bottom keeps the boiler mixed.  Just my $0.02

IACG: is this an indoor installation?  just checking on the lack of insulation on the lines, and the obviously exposed temp sensor on the line in the foreground of the boiler rear photo.

@brant2000: as I understand it, the flow patterns in auto engines also are designed to keep the air elimination function at the top of the radiator.


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## slowzuki (Mar 5, 2015)

Based on what you're saying there is a problem with stagnant areas in the heat exchanger boiling while cold water bypasses that area despite the baffles/manifolds fix they tried?  Their graphic of the inside of their boiler looks like a conventional fire tube hx although the sump area of the tank is pretty tight.  Stratifying isn't the right word to use but I see what you mean.



James Reimer said:


> Speaking to a troubleshooting rep for Heatmaster, the G200 is very sensitive to supply/return flow rates.  Apparently there are baffles and manifolds inside the boiler that direct cold water to certain places.  If the flows are not at least 14 GPM there is a stratification issue inside the boiler and the supply water will never get hot while the top of the boiler will boil over.  Having low flow and a high delta T like this scenario is, it will only exacerbate the problem as the cold water will fall to the bottom of the boiler and cause extreme stratification.


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## tom in maine (Mar 5, 2015)

In going through two pages of answers, the simple answer is that you still have inadequate flow in the system. If the boiler requires 14gpm, I think I can guarantee that there is no way this system as plumbed will ever do that.
This system would greatly benefit from a primary/secondary plumbing design, separating the garage from the house, putting them both in parallel.
A flow meter or two would be appropriate as well.


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## James Reimer (Mar 5, 2015)

slowzuki said:


> Based on what you're saying there is a problem with stagnant areas in the heat exchanger boiling while cold water bypasses that area despite the baffles/manifolds fix they tried?  Their graphic of the inside of their boiler looks like a conventional fire tube hx although the sump area of the tank is pretty tight.  Stratifying isn't the right word to use but I see what you mean.



Correct.  The stagnant area directly on top of the firebox boils when the fan is running while the rest of the boiler doesn't get up to temp.  This is due to inadequate flow rates for this boiler.


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## cpeltier (Mar 5, 2015)

James Reimer said:


> Speaking to a troubleshooting rep for Heatmaster, the G200 is very sensitive to supply/return flow rates.  Apparently there are baffles and manifolds inside the boiler that direct cold water to certain places.  If the flows are not at least 14 GPM there is a stratification issue inside the boiler and the supply water will never get hot while the top of the boiler will boil over.  Having low flow and a high delta T like this scenario is, it will only exacerbate the problem as the cold water will fall to the bottom of the boiler and cause extreme stratification.
> 
> In typical boiler designs with storage stratification is your friend, but in this model of boiler the supply and return are located closer together in the middle of the water jacket. This is a unique situation for this model of boiler that doesn't happen to other manufacturers that have the supply at the top and the return at the bottom.
> 
> To resolve the issue he needs to get the flow rates up with a secondary mixing pump, or make some plumbing adjustments and add another pump for higher flow rates.



I've seen older combination boilers that stratify like this and require a small pump (Taco 007 or equiv - almost no head loss) that simply recirculates between the supply and return to provide mixing within the boiler. This pump would run whenever the fire is burning. With all of the PEX in this system it may be easy to try.


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## Clarkbug (Mar 5, 2015)

Why not hook that pump up in series with the existing one as a troubleshooting measure?  Might get some more flow moving until more permanent solutions can be found...


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## maple1 (Mar 5, 2015)

tom in maine said:


> In going through two pages of answers, the simple answer is that you still have inadequate flow in the system. If the boiler requires 14gpm, I think I can guarantee that there is no way this system as plumbed will ever do that.
> This system would greatly benefit from a primary/secondary plumbing design, separating the garage from the house, putting them both in parallel.
> A flow meter or two would be appropriate as well.


 
I am thinking that if a boiler requires that much flow through it when burning (and it sounds like the case here), it should have and come with a pumped bypass loop to ensure it. I don't have great exposure to a lot of systems - but 14gpm is sounding kind of on the high side for system flow, and more often than not a typical system won't flow that much. I could be wrong on that, but mine flows less than 10. What would a typical range of system flows be?


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## Karl_northwind (Mar 5, 2015)

14 gpm in a typical 200,000 btu boiler system isn't out of the ordinary at all. 
 200,000 btu at a 30 degree delta T= 13.5 GPM.


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## cpeltier (Mar 5, 2015)

maple1 said:


> I am thinking that if a boiler requires that much flow through it when burning (and it sounds like the case here), it should have and come with a pumped bypass loop to ensure it. I don't have great exposure to a lot of systems - but 14gpm is sounding kind of on the high side for system flow, and more often than not a typical system won't flow that much. I could be wrong on that, but mine flows less than 10. What would a typical range of system flows be?



14GPM at a typical 20F delta T is 140 BTU/hr. That's a lot of wood to burn and heat to move without a bypass loop, primary/secondary loop or storage system. The way this system is setup now his delta Ts could be much higher with the sequential loads finishing with radiant heat. I would add a short primary loop feeding the secondary loop with a high head circulation pump (Taco 009 or 011) or another pump in series as already suggested. The run length is so far that getting over 10GPM will be next to impossible. The fan coil may also have a significant head loss at these flow rates and may need a bypass zone valve.This is a non-pressurized system so i assume you must use non-oxidizing and more expensive pumps.


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## slowzuki (Mar 5, 2015)

Trying to force more gpm through the long loop is expensive if you don't need the BTU's in the house but just need mixing.  Cheaper to circulate at low head through the boiler like other posters mentioned earlier.

What a fundamental problem to have in the boiler though, you'd think they would have picked that up.  With the extra ports on the back maybe they anticipated one set just for a mixing pump.

BTW its not really a 200k boiler, only something like 111k if you read the literature.


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## IACG (Mar 6, 2015)

The dealer came back with some suggestions today.

1)  Put a larger pump (Grundfos 26-150) the equivalent of 2 -2699’s on the line that runs to your house. Take the 26-99 that is currently on the line and move it to the line that runs your floor heat in your shop.

2)  Add an additional 26-99 on the return line from your house and replace the 15-58 that is running your shop floor with a 26-99.

3)  Add a 26-99 to the bottom of your stove where the 1” drain valve is. Attach the pump to both of your return lines essentially creating a circulating loop.

He figured the second option was best option.  He says that the two smaller pumps working together would be more effective than one large one.  With the addition of that pump and the upgrade of the 15-58 he says there should be enough flow to prevent thermal layering.

I asked him about the thermal shock having such a large Delta T.  He says that it is not a problem.  He contacted the manufacturer and they too say it is not a problem to send back really cold water. The told him, "The only way that it could potentially become an issue is if you had very cold water ( close to freezing continuously running back to it.) With the way its set up the water that runs back to the boiler instantly mixes with the other 150 gallons that are already in there, so it is highly unlikely that it would ever become and issue."

I was wondering if this option would be better:

Running a small pump on Ts from the shop loop.  There are 1" Ts already mounted on the supply and return of that loop.  Because there would be virtually no head in this loop enough flow would not be a problem. I was just not sure if the way the Ts are set up if I would this pump draw too much flow away from the shop loop.  This does not solve the large Deta T issue, but the dealer assures me that I would be wasting my money buying a mixing valve and such to warm the return line from the house.  In fact, he figures the added resistance would cause even more of an issue.

So what do you guys think of his suggestions (or my idea?)

Thanks for all your advice.


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## IACG (Mar 6, 2015)

Tennman said:


> Do you have an estimate of how much energy you want/need to dump into the house? If so I can plug that into a spreadsheet to compute gpm, velocity, and head based on your 1" pex which will tell you if the pump's adequate. Unless you have a very efficient home that's not too large, 1" is pretty small for those distances. Which means to move more btus/hr you must increase velocity, which increases head, which increases pump horsepower.
> 
> Somehow get the temp of the water entering your underground and the temp where it exits to get the temperature loss in underground. I lose about 1* or less in about the same distance (2*F round trip including thru the HX when fan's off). The source of our boiler said 1" would be adequate, but I did the math and installed 1 1/4"... for our boiler which is roughly in your class, our install would be more efficient with 1 1/2". I was in similar circumstances 6 years ago and the guys here helped me sort it out.  In my case years ago it was multiple problems I needed to address. But checking pump size is a start. The diagnosis process often involves going down the list identifying what it's not.
> 
> BTW.... Did you read the underground sticky? The pipe drain I used for my first underground was not perforated, but when I sprayed foam inside I was shocked to see all the tiny pin holes. When I dug up my first underground install it was all filled with water and mud. I was losing a huge amount of energy to the dirt. Yes... too bad you discovered this site after the fact, but you'll get lots of great help here.



I don't have a number for the estimated heat I need in the house.  Here is what I have in the house currently: The furnace has 18 kilowatts of elements.  The house by the way is just under 2000 square feet.  It is a one and three quarter story and it extends over the garage.  The living room has a vaulted ceiling open to a loft.  I would have to do some figuring as far as volume is concerned.  I also have a wood stove in the living room which we try to keep going most of the time.  I want to use it less once I burn wood in the boiler though I don't plan to stop burning in the house.  The attached garage is approximately 675 square feet.


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## maple1 (Mar 6, 2015)

*I asked him about the thermal shock having such a large Delta T. He says that it is not a problem. He contacted the manufacturer and they too say it is not a problem to send back really cold water. The told him, "The only way that it could potentially become an issue is if you had very cold water ( close to freezing continuously running back to it.) With the way its set up the water that runs back to the boiler instantly mixes with the other 150 gallons that are already in there, so it is highly unlikely that it would ever become and issue."*

*This does not solve the large Deta T issue, but the dealer assures me that I would be wasting my money buying a mixing valve and such to warm the return line from the house. In fact, he figures the added resistance would cause even more of an issue.*

Still leery about this stuff. It's not so much 'thermal shock', but rather extended periods of sub-140 water returning & causing increased creosote condensation inside the boiler. This would be the case with every other wood burning boiler I have heard of - but this does seem like a different beast, so not sure what to say.


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## Karl_northwind (Mar 6, 2015)

I would pipe it up primary secondary.  something like 1.25" pipe from top port to bottom port, with a 15-58 (or grundfos alpha)  pumping from bottom to top.  
have a series of tees in that pipe, that allow hot (bottom) to be pulled off (via the 2699 to the house, and the other circ to the shop) and the cold return back in to the top of the boiler.  a standard primary secondary setup, which will keep the return temps up, the proper flow rates for the boiler, and all will be happy.  
the distribution flow rate to the house is a separate issue. 

 the 2699 ought to push about 5-6 gallons per minute thru all that PEX.  that's going to return a really high delta T if it does the load at all. 

 separate the boiler operation criteria from the heat distribution issues.  

karl


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## slowzuki (Mar 6, 2015)

Gasifiers aren't as critically sensitive to return temps for burning but it can cause condensation inside the heat exchanger that will shorten the life.  There is still the problem of load management if you don't have return protection.  Too much load will drag the boiler temp down and prevent you from having high temp water for your high temp loads.

Stirring the boiler isn't going to fix that, the heat absorbed in the primary chamber should be well under 1/2 of the boiler output, somewhere around 1/4.  Capture of that with stirring isn't going to solve your whole boiler being dragged down when your slab loads are both calling.



maple1 said:


> *I asked him about the thermal shock having such a large Delta T. He says that it is not a problem. He contacted the manufacturer and they too say it is not a problem to send back really cold water. The told him, "The only way that it could potentially become an issue is if you had very cold water ( close to freezing continuously running back to it.) With the way its set up the water that runs back to the boiler instantly mixes with the other 150 gallons that are already in there, so it is highly unlikely that it would ever become and issue."*
> 
> *This does not solve the large Deta T issue, but the dealer assures me that I would be wasting my money buying a mixing valve and such to warm the return line from the house. In fact, he figures the added resistance would cause even more of an issue.*
> 
> Still leery about this stuff. It's not so much 'thermal shock', but rather extended periods of sub-140 water returning & causing increased creosote condensation inside the boiler. This would be the case with every other wood burning boiler I have heard of - but this does seem like a different beast, so not sure what to say.


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