Boiler help please

[scottz]

My house has a hot water boiler system feeding baseboard radiators. This fall I installed a new boiler. I am the homeowner and did it myself. Everything worked fine until temps got down around zero. Now the system is not keeping up. I have the thermostats (3 zones) set to about 68-70 but the air temp is not getting above the low 60's. The boiler cycles properly and I'm pretty sure the circulation pump is running almost constantly (it would have to be with the thermostats always calling for heat). I can feel heat at the radiators, just not hot enough. The only gauge on my boiler is on the return from the house. It indicates 125 degrees and 12psi. My laser temp probe indicates about 88 on both input and output, but this is not a very accurate measurement. My high limit aquastat is set at 240 degrees (max). I have no way of knowing if the boiler is actually heating up to 240 before it cycles off.

I'm thinking the aquastat is defective and not letting the boiler heat up enough. I have a new one on order and will try that when it gets here.

Any thoughts or advice is appreciated.

Thanks

PS: the old boiler heated the house just fine; I only changed it because it was 30+ years old.

Old Boiler
Burnham, Input BTU 150,000

New Boiler
Hydrotherm model HW-175-INTD, Input BTU 175,000

[hvactech126]

Im assuming you used the same BTU rating boiler as you had?

[paul52446m]

My house has a hot water boiler system feeding baseboard radiators. This fall I installed a new boiler. I am the homeowner and did it myself. Everything worked fine until temps got down around zero. Now the system is not keeping up. I have the thermostats (3 zones) set to about 68-70 but the air temp is not getting above the low 60's. The boiler cycles properly and I'm pretty sure the circulation pump is running almost constantly (it would have to be with the thermostats always calling for heat). I can feel heat at the radiators, just not hot enough. The only gauge on my boiler is on the return from the house. It indicates 125 degrees and 12psi. My laser temp probe indicates about 88 on both input and output, but this is not a very accurate measurement. My high limit aquastat is set at 240 degrees (max). I have no way of knowing if the boiler is actually heating up to 240 before it cycles off.

I'm thinking the aquastat is defective and not letting the boiler heat up enough. I have a new one on order and will try that when it gets here.

Any thoughts or advice is appreciated.

Thanks

PS: the old boiler heated the house just fine; I only changed it because it was 30+ years old.

Old Boiler
Burnham, Input BTU 150,000

New Boiler
Hydrotherm model HW-175-INTD, Input BUT 175,000

If you turn all your stats up and watch the boiler does the boiler stay on or is it turning off and on? What size pump is on this new boiler? and what pump was on the old boiler? Usually you only get about a 15 degree drop from supply to return. Do you have a control limit and a back up limit? and are they both set to a higher setting? What is the footage of radiation in your house.
Are you getting any gurgling in the pipes? Is your supply and return on the boiler at least 1" pipe? What is the sq. foot of your house. How many stores is your home? and is your boiler in the basement. Paul

[scottz]

Im assuming you used the same BTU rating boiler as you had?

Old one was 150,000; new one is 175,000.

[scottz]

If you turn all your stats up and watch the boiler does the boiler stay on or is it turning off and on? What size pump is on this new boiler? and what pump was on the old boiler? Usually you only get about a 15 degree drop from supply to return. Do you have a control limit and a back up limit? and are they both set to a higher setting? What is the footage of radiation in your house.
Are you getting any gurgling in the pipes? Is your supply and return on the boiler at least 1" pipe? What is the sq. foot of your house. How many stores is your home? and is your boiler in the basement. Paul

*The boiler cycles off & on. I have not timed it, but it is not quick.

* The new boiler came with a Taco 007-F5 pump installed (boiler is Grainger PN 2PE81 or Hydrotherm HW-175-INTD if you want to look it up). My old boiler had a B&G 106189. When I first saw the new boiler I was concerned about the small size of the Taco compared to the B&G, but I figured Hydrotherm knew what they were doing. Everything was fine until it got really cold.

*I don’t think I have control or back up limit; not sure what that is, but if I had it, I would know.

*The house is almost 3000 sq ft, three levels, each level is a zone.

*No gurgling, but I was getting a loud water hammer. I kept purging the air until I didn’t get any more, but still had the hammer. Funny, I have not heard it since it got really cold. I’m pretty sure it hammered when the pump shut off; it probably has not shut off in days; probably why I have not heard it lately.

*Yes, 1 ¼”. I did not change much piping, just a little to accommodate the input/output locations on the new boiler.

*The boiler is in the garage which is about half way vertically between the lower and middle level. The elevation change between the lowest and highest level is only about 8’.

Thanks for taking the time to respond.

[scottz]

I tried to attach a photo, but cannot until I have 15 posts.

[scottz]

You can see a photo of my equipment at picasaweb.google.com/esz999
in the "house" album.

[scottz]

I just ran another test. I took a sample of water from the boiler drain, it measured 130 degrees. My high limit aquastat is set at 220, so why the low temp?

I have a new aquastat (Honeywell L4080B-1253) on order, should be here Tuesday.

[scottz]

I bypassed the high limit switch and ran the boiler until the 30PSI relief valve popped. Water temp at boiler drain: 155 degrees.

[scottz]

I just checked the aquastat on my old boiler (I saved the controls and pump), it was set for 180; heated the house just fine.

[scottz]

Thinking aquastat or the circulation pump is too small.

[scottz]

http://picasaweb.google.com/esz999/House#5558926889462482018

[paul52446m]

I just checked the aquastat on my old boiler (I saved the controls and pump), it was set for 180; heated the house just fine.

I have read all your post, the reason the water temp at the drain is so low is because you water if flowing so slow that the temp. drops way down on the return at the bottom of the boiler. You should never turn you limit above 210
degrees. The normal setting is 180. You said at one point you had the limit set at 240. at 240 you would be flashing off to steam inside the boiler and that is why your pipes were banging. that 007 new pump does not compare to the B&G
that you had. i do not think you are moving enough water to heat the house.
Paul

[paul52446m]

Thinking aquastat or the circulation pump is too small.

I looked over your pic. You said you only had a temp gage on your return line.
The line coming out of the top of the boiler on the left rear corner is the feed line leaving the boiler. The return line is the line that the pump is on in the side of the boiler. Check the pump and see if the arrow on the back side of the pump
is pointing down so it is pumping into the boiler. If you are not flowing the water
through the boiler the right way it will not be going through all the sections and will not heat much. If you are running the water the wrong way through the zone valves it will make them hammer every time they close.
You are not getting this job inspected are you ? If you are i will tell you other things that are to code. Later Paul

[scottz]

Problem solved:

http://picasaweb.google.com/esz999/House#5559319849534324754

I pulled the Taco pump and installed the B&G from my old boiler. Works great now. Hi limit set back to 180.