Troubleshooting: Not providing enough heat..

Ross_24

This boiler feeds a single hydro-air unit in the attic. The client complains that during the cold winter months the house will not break 63F. This is a small, slab house in Massachusetts. Did not take enough pictures here, but it was a poor installation with questionable choices made. So, how do I get her house warm again?

First things that jump out at me:

1. There is only a 1/2" line feeding the hydro-air unit which supplies heat for the entire home. I have not done a heat loss analysis as I simply did a quick inspection this morning, but based on experience it would be somewhere around 50,000 BTU/H. The 1/2" line is circulated with a Grundfos 15-58 on High. This was the first thing that jumped out at me and I think it just can't carry the BTUs required in the middle of winter.

Note: You can make out the circulator and the 1/2" copper supply and return in the video below. Poor quality I know, but you can make out the lines and hear the grumbling circulator.

3. The closet is SMALL and the last contractor that was here blocked up the make up air because "it was too cold". The boiler definitely needs combustion air.

3. All duct lines are sufficiently insulated and the hydro-air unit is working.

4. Boiler is surprisingly not over-sized but plenty for a small house like this. It can provide the BTUs needed.

Always value the thoughts on this forum. What do you think?




https://www.youtube.com/watch?v=ro8yuUtBkr8

RobG

First question. did it ever work?

Ross_24

From what I've gathered from her, it hasn't worked since installation.

wogpa67

What are the settings on the 2107?

Steamhead

That 1/2" line is too small.

Ross_24

wogpa67 said:

What are the settings on the 2107?

It's currently set to manual 180F supply, no ODR. Although I'd imagine the auto ODR will work well once I fix the 1/2" supply/return issue.

Steamhead said:

That 1/2" line is too small.

Thanks that's what seemed to be the culprit to me. Always glad to hear others advice.

Marz

Once the 2107 is set to auto again, be sure to set the heating curve to run with hydro air. Buderus tech support has a bulletin on how to do this.

Ross_24

Marz said:

Once the 2107 is set to auto again, be sure to set the heating curve to run with hydro air. Buderus tech support has a bulletin on how to do this.

Wow, thanks. That I did not know!

SWEI

Is the hydro air coil sized properly?

RobG

How long is the run to the AHU and what is the BTU/ flow rate. That pump does not sound right. It should be virtually silent.

Ross_24

SWEI said:

Is the hydro air coil sized properly?

The coil is sufficient to heat the home. It was installed in the 1980s. Hasn't heated the home correctly since 2006 when this boiler was installed.

RobG said:

How long is the run to the AHU and what is the BTU/ flow rate. That pump does not sound right. It should be virtually silent.

You're right it sounds terrible. It's a run of about 25 ft of 1/2" total pipe. I'm not sure what the head loss of the hydro-air unit is. The circ has the classic marbles inside sound.

EBEBRATT-Ed

Increase pipe size and increase water temp. Check temp drop across coil (water & air)to see if the coil is performing to spec.

4Johnpipe

I do not think you are getting enough BTU's through the 1/2" line. Is the strap on aqua stat on the supply or return side of the hydro coil?

bob eck

According to the Burnham Heating Helper Book
1/2" copper supplies 17,000 BTU
3/4" copper supplies 39,000 BTU
1" copper supplies 71,000 BTU
What is the supply and return size of this boiler. There is a reason for that size.
50,000 BTU needed should be 1" supply and return to the duct coil.

bob eck

The duct coil needs to be the right size and so does the duct.

wogpa67

with whats existing speeding up the flow of water and air will give better heat exchange.

Brainf@rt!
Very long day yesterday.

Marz

IMO I would set that logomatic correctly first. The offset is set to 9 along with maybe 6 other changes.

Charlie from wmass

Start with the curve as said already and change piping to get better efficiency in the long run. Even if the coil is restrictive larger piping will make a big difference

Gordan

wogpa67 said:

with whats existing slowing the flow of water and air will give better heat exchange.

Seriously??

Charlie from wmass

We kind of skipped that one @Gordon .

Ross_24

Thanks for all the advice guys it's been a great help.

Can anyone help me get literature for the air unit? Can't seem to find it.

Advanced Distributor Products
Model 065608104

simmons_plumbing

1. What is the square ft of the heated space. In order to know if proper sizing was done on.
A. Boiler size example of Sq Ft x 50 should give you an approx amount of BTU's needed to heat the space.
B. Coil size
c. Fan / CFM for ductwork sized to small or return air to small/
dirty filter.

Need much more info to really help you get it correct.

PS the system has air in it if you hear noise from pump like that.

SWEI

simmons_plumbing said:

A. Boiler size example of Sq Ft x 50 should give you an approx amount of BTU's needed to heat the space.

Huh?

Charlie from wmass

Wait I thought this was heatinghelp.com not ask.com.

Ross_24

Ok, so the air handler specs say it will provide 50,000 BTU with 160F water temp, 3 GPM and 1200 CFM. It will provide 55,000 BTU with 180F water temp, 2 GPM and 1200 CFM.

I will recommend an increase in supply and return sizing to 1" and replace the circulator while I'm at it. I will also add make up air and correct the 2107 settings.

Rich_49

Even in Poiunt Barrow you should perform a heat loss . Hey Charlie , 30 BTU sq ft South of the Pike and 40 North right ?

Charlie from wmass

Rich I have some old farm houses that are nearing 55 but I now am a big fan of accurate heat losses.

icesailor

Rich said:

Even in Poiunt Barrow you should perform a heat loss . Hey Charlie , 30 BTU sq ft South of the Pike and 40 North right ?

Same as East & West of Wusta'a huh?

icesailor

Some old dead and almost dead guys found that checking the temperature of the water going in and water coming out of a fan coil with the AH fan running can give a really good indication of whether or not there is enough water flow running through it. The higher the Delta T, the more heat given off. If it comes out too cool, the flow is too low.

When the circulator and boiler are running, and the AH fan is running, check the outlet water temperature. Turn off the AH fan. If the temperature goes up appreciably, the flow is too low.

Did the lover of the new Universal heating pipe size, 1/2" PEX, perhaps switch the lines and is feeding the supply on the AH with the return? The coil is marked for a reason. You might find out why. The manufacturers that know a lot more than most of us, put that sticker on for a reason.

0 to 30# pressure gauges at the boiler or AH showing the pressure differential through the coil can be a really helpful tool in deciding if the boiler is big enough and the flow too low through the coil. Due to undersized spaghetti tubing.

That's true even in Point Barrow.

Ross_24

Great points. The handler was showing a 40+F Delta T.

Here's a question: Once I make the changes I've mentioned above, how could I test it? Now that we are in the shoulder months, the system is heating the house up to temperature.
In the middle of the winter with single digit temperatures, she mentioned it never got above 63F.

Would I simply check the Delta T for proper changes? And if it creates a lower delta T I know I've made it?

Makes me think of the old tests described in Dan's LAOSH. Back when steam systems were installed in the summers. They were required to heat a house up to 110F on an 80F summer day to prove it worked. I'm guessing on those numbers but it was something like that.

Charlie from wmass

Aim to a higher set point. Try heating up to 80.

icesailor

IMO, put in ports for pressure gauges, The pressure differential will tell you more than anything else. The pressure differential gives you head pressure. The Delta T(emperature) gives you how many degrees/btu's are lost through the AH. A 40 degree Delta T is usually an indication of a lot of heat loss through an emitter or zone. Especially if the piping is too small and the flow is restricted. If the piping is adequate, the pressure/head differential is usually less and the Delta T is smaller. Meaning that more heat is given up into the emitter through the higher flowing water. Also, check the Delta T of the air going into and out of the AH.

If the owner says it worked before the boiler was replaced, and it hasn't worked since the boiler change, The boiler seems plenty big enough, but 1/2" PEX seems rather small.

Rich_49

Do you have the specs for the installed coil to post here .

Ross_24

Rich said:

Do you have the specs for the installed coil to post here .

I couldn't get the specs sent to me for some odd reason. Tech support gave me the heat output numbers mentioned above over the phone. They said I would not be able to get any literature. Maybe I should try another call.

I found this through their site and I think I narrowed it down to the #36 model.

http://www.adpnow.com/wp-content/uploads/2010/10/SG-BAH-16.pdf

*EDIT* All the heating output is on pg. 12 looks like this is the correct literature

Rich_49

Are you certain you have the 3 row coil ? 3 gpm should not be that difficult to provide . You will need 3/4" however.

Charlie from wmass

Really need to have the same delta T as you would have in February. So heat the home to 90 degrees above the outside air temperature.

Charlie from wmass

Wait. I was just referring to the way the old timers would prove their systems by guaranteeing a temperature rise. But why can I not raise a house to 120 if I have the btus to do it?

Charlie from wmass

but if you have 180 degree water how warm can you heat the room?

Charlie from wmass

Why , for testing purposes in the shoulder months could you not over ride the high limit for the supply air?

Rich_49

Take aquastats out of the equation and design based on water temp and coil . Air systems continue to use a single delivery temp for the most part and change cfm of blower. Can a house that is 22,500cf be heated properly while only moving 16,000 cf an hour ? Better yet , why would you use a coil with 180* water and 800 cfm speed in a house that needs 375 cfm ? Maybe we should design a buffer tank for hot air systems !
We have done this successfully in jobs where the air side HVAC professional told us he needed 180* water . After researching the coil specs we determined that those coils would never need water more than 150* and would heat the house nicely with 110* fluid during the shoulder seasons . He thought we were nuts but had enough doubt to allow us to try our madness . It all worked fine . 5 coils and air handlers with ODR , Delta T pump receiving water heated by an HTP Phoenix . No ECM fans , no crazy learning furnaces , just sound heat loss numbers and design . Imagine throwing in a mod con and running it at 180* and telling the homeowner he has a 95% AFUE system ?

icesailor

That all really isn't so. There's the Short Bus method, utilized by Short Bus riders all over.

Turn on the circulator and keep the fan OFF. Let the pump run and pump the hottest water you can through the coil. Feel the inlet and outlet of the coil. The inlet should be hot, very hot. Almost as hot as the boiler water leaving the boiler. If it isn't, the undersize PEX needs to be insulated. The smaller the pipe, the more wall surface and the greater the heat loss.

Once established, turn on the fan. The return temperature should drop. By how much is what is being given off in the coil. Some Short Bus riders have noticed that a fan coil on high, can have a cold outlet with higher fan speeds.

Its been reported that some who ride in the front of the Short Bus, have had a hard time grasping the concept that if you have a 10,000 BTU radiator piped with 1" copper tube and run 180 degree water into it, and it leaves at 170 degrees, and another 10,000 BTU radiator with 180 degree water. piped with 1/2" CTS PEX and a 40 degree Delta T (140 degrees), how the same radiator that isn't as hot throughout the whole radiator is giving off more heat than the radiator pipes with a bigger pipe and the whole average radiator temperature is 175 degrees.

Maybe that's why they ride on the short bus.

Or the school system cut spending in special needs programs and those who needed to ride on the Short Bus, had to walk and didn't get that window gazing time to ponder life's intricacies.