steam heat efficiency

Burke O'Neal

We have steam heating for our 12 unit housing cooperative and it is well balanced and works great (we have TRVs in the rooms that used to overheat). I noticed that the exhaust coming out of our 3 story masonry chimney is cool enough to touch and readily condenses on my hand. The chimney is internal to the house. The metal exhaust pipe that connects to the chimney in the basement is extremely hot. Is our effective efficiency higher than the 82% the boiler is rated at? Is the heat in the chimney working its way into the house? Has anyone tested boiler efficiency including chimney heat gain? I realize some of the heat is going up the chimney when the boiler is off, but this time of the year in Wisconsin the boiler is on at least 50% of the time. Would a damper in the basement exhaust pipe improve this effect if it's real?

Thanks, Burke

Steamhead

Burke, you need a good service tech

properly equipped with a digital tester that can measure stack temperature, draft, oxygen, CO and CO2 levels, and excess air. I have a hunch that boiler may be ingesting too much excess air, which can cause a hot flue and waste a lot of gas. But it shouldn't be readjusted except by someone with the proper equipment and know-how.

Stack dampers are a controversial subject. I happen to like them, especially on old chimneys designed to produce the high draft needed to operate a coal boiler. Since your building has steam heat, it probably had one of these coal boilers. Such a chimney can pull all the heat out of an atmospheric gas boiler in a very short time after the burner shuts down. I think you'd see a reduction in the burner's run-time with a damper. But be sure to check with the boiler's manufacturer for their take on the subject.

There are some concerns about condensation in the chimney when dampers are used, but I think the chimney stays warmer if the heat cannot rise out of it because of a closed damper. Also, some early dampers weren't reliable, but newer ones seem to be much better.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Burke O'Neal

Thanks for the suggestions. We are expecting a technician from a reputable hydronic contractor to do our yearly checkup this week. I will ask him about the tests you suggested and also about the damper. I will also contact the boiler manufacturer and see if they can recommend a damper. I don't know if you're allowed to mention specific brands, but are there dampers you have had success with?

Thanks, Burke

Steamhead

I see a lot of

Honeywell and Effikal units. They appear to hold up well. Some boiler manufacturers market dampers for replacements and upgrades- if yours does, I'd go with their recommendation.

We also have some really fine boiler manufacturers represented here on the Wall. Tell us what you have and we'll try to point you toward your rep.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Burke O'Neal

Our boiler is a Weil-Mclain. I think it's about 10 years old. I don't see any model numbers on it, but it says it is rated at 325,000 BTU/hr and it has a 12" flu.

Burke

Steamhead

You're in luck!

The Weil-McLain rep who hangs out on the Wall is Bill Wright. You can e-mail him at bwright@weil-mclain.com . Tell him as much as you can about your boiler and I'll bet he can identify it.

Bill is relatively new to the Wall, but what I've seen so far tells me he's a welcome addition.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"