Indirect hot water heater on steam boiler

Bob_57-2

I recently modernized my steam boiler getting rid of a 80 year old unit and replacing it with a Burnham IN-6. I also replaced my stand-alone gas fired hot water tank with a Heat Flo indirect.



The indirect works very well in terms of providing sufficient hot water. However, I'm surprised as to how hot my basement gets from the furnace cycling on for a minute or so to heat the water. The boiler has a Honeywell control to limit the heating to 180 degrees and no steam is being produced. My radiator vents do whistle as the furnace is heating water but I guess that makes sense. The steam pipes in the basement within about 15 feet of the boiler get warm (I can feel an uninsulated part next to a hanger). The vent to the chimney flue gets very warm which is I guess the source of the heat.



I'm wondering if I made a mistake getting an indirect, given how much heat is being thrown off in the non-heating season months. I'm also surprised how often the furnace cycles on even with no hot water demand. I've insulated the supply pipes to the indirect with at least 1/2" thick pipe insulation (it ended up being a long run to the indirect)



Thanks for any advice you and offer

nicholas bonham-carter

Whistling hot water

I would say that if your radiator vents are whistling, then some steam is being made. This also would indicate to me that your main ( not radiator) venting is inadequate, and that you are burning extra fuel to force the air out of the supply pipes through the radiator vents as steam rises.

Is this one of those setups where the water level should be raised up in the summer to cover the coil?--nbc

Bob_57-2

no main vent

Thanks for your reply, Nicholas



Interesting that you raise the issue of main vents. I have none in my system. The pipes in the basement do a full loop and return to the boiler. Remarkably my heating bills (in New England) have been low for the 27 years we've been in the house.



Can you explain a bit more what you mean about covering the coil?

Hoog23

I have the same issue on a new install too

New 4 section G8 and Carlin EZ-Gas.  I have a main vent and plenty of water in the boiler.  Steam moves quickly so I would suffice that the main is working properly.



I had a temporary electric hot water heater over the summer (I think I would win a medal for the longest conversion) and my basement was nice and cool.



I'm going to ask my plumber to adjust the temp on aquastat.

Charlie from wmass

Can you post some photos?

If you could it would help us see better what was done. A boiler does produce steam trying to satisfy an aquastat set for 180 the up portions of the sections get warmer than the level the aquastat is set at.

Bob_57-2

pictures

Here are two photos of my system. The water heater is visible on the left side of the second picture. Let me know if any other "poses" or zoom-ins would be useful. Thanks for everyone's help.



Bob

Ron Jr._3

Can't see in the pics

but where is the aquastat located in the boiler ?



If the boiler is running even without a call for heat or hot water it sounds like a wiring or aquastat placement issue . Is the boiler is maintaining temperature all the time ?

lchmb

looking

at the manual, the aquastat will be on the oposite side of what we see. It uses N as a supply, M as a return and tapping P for the aquastat. These can be found on page 20 in the manual.

http://www.usboiler.net/products/boilers/independence/assets/manual-ind.pdf

It does say to set to 180 degree's, so if done properly I would check to make sure the aquastat is installed properly (probe fully installed into well) and is shutting down on temp. As Ron mentioned, does the boiler maintain temp? If so, I would rewire it for cold start and run the indirect at a higher temp with mixing valve if you dont already have one...

Bob_57-2

aquastat

it's installed exactly as you've mentioned, i.e., by the book (see the picture below)



The boiler doesn't run all the time but I'm surprised how often it comes on, meaning every few hours with no demand. Is this reasonable in warm months?



My bigger concern is how hot the basement gets, with steam pipes feeling warm to the touch about 15 feet from the boiler. Is this to be expected?



Regarding the boiler maintaining temperature: I'm at work now so the boiler is not nearby. Is there a temperature gauge on the boiler I should be looking at?



thanks

lchmb

wiring

If the aquastat is wired to call the boiler on it will maintain what ever temp it is set to. You would need to have a control that, when your hot water heater calls will then work through the aquastat to bring the boiler to temp.. And when there is no call will allow the boiler to go cold. How is the circulator for the indirect controlled?

Bob_57-2

control

There's an electrical cable running from the circulator to a control box (on the right side of the boiler but near the front). Then there's another cable to the aquastat which is set at 180 (which I assume is the high temp limit). I don't know what that first box does and it has no obvious controls on the outside. The brand label is Argo.

RobG

boiler cycling

In regards to your boiler cycling frequently, with a mixing valve installed on the indirect, increase the indirects aquastat setting to 170 and adjust the differential setting on the aquastat to 30 degrees. That way if the tanks is at 170 degrees, the boiler will not kick on again untill the tank temp drops to 140 degrees. Just be sure that you do have a thermostatic mixing valve installed to lower the domestic water outlet temp to 120 degrees or so to prevent scalding. Hope this helps .

Rob

Bob_57-2

differential

Thanks for the interesting reply, Ron.



My indirect water heater is a Heat-Flo with a Honeywell 4080B aquastat. From what I've read this has a fixed differential of 15 degrees so I'm not sure if I can reduce the boiler cycling with your idea. Am I wrong about the fixed differential?

Charlie from wmass

Bob

the boiler is now firing to maintain temp even when there is no call for heat. I have my boilers installed to be "cold" start with the boiler not firing unless the tank is calling for heat. This allows for the boiler to remain off until the domestic water calls for a cycle and means the boiler may cool down to room temperature between firing. There are draw backs to "cold" start but it has saved fuel on the installs I have been involved with. This means the use of a circulator relay that has an end switch that can be put in series with the aquastat. This also allows for the vapor to not be warming your mains all day.

Bob_57-2

Problem solved

Charlie nailed it. Finally got the head plumber over to my house today. When he heard the problem he realized that the electrician wired the aquastat in parallel with the thermostat. So he rewired it in series and also lowered the high temp cutoff on the boiler to 160, down from the 180 specified by Burnham.



I haven't had a chance yet to fully test this new setup, ie. watching it over time. But it all seems to make sense now.



Thanks again to all who replied to my original post.

Charlie from wmass

Glad you are up and running

I love it when I get one right.