Flue Damper Efficiency Gains

Sean Flynn

Does anyone have any idea how much efficiency might be gained by adding a flue damper to a 20 year-old Burnham Furnace? We've basically just rebuilt the unit, but I wondering if adding a flue damper can save us enough to warrant the expense?

Thanks in advance,

Sean

Boilerpro_3

Older Info

I had some older Peerless boiler info at one time from when stack dampers where an option. Typically the AFUE increased about 8% on a residential type boiler. If the boiler is oversized or connected to a large old coal type chimeny (it should be lined with the proper size liner), savings will probably be greater. I know on my own 45 year old American Standard (predecessor to yours) the boiler would go ice cold in a few hours, even with a standing pilot. When I put on a thermally actuated damper (not very airtight), the boiler would stay at about 100F just from the pilot.
The folks at both Burnham and Weil Mclain say dampers are only worth a couple points of efficiency, but experience by many here seems to dictate otherwise.

Boilerpro

Richard Lemelin

on a flue with a single appliance, adding a flue damper may cause the chimney to cool off too much between cycle, thus causing excessive spillage (downdraft) when there is a call for heat.

Unknown

It depends

The efficiency gained with a damper will depend on the whether the boiler is gas or oil, the age of the boiler as well as chimney draft and other factors. If the boiler is oil-fired I would advise not installing a damper (not made anymore for oil) and depending on the model and age of a gas-fired boiler, there will be more to it than just installing a damper. There are redundant safety devices that will also need to be installed as well such as a blocked vent and flame rollout switches. The wiring harness will also need to be modified to accomodate the damper wiring harness. In most cases the percentage of savings may only be a few percentage points. Hope this helps.


Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Steamhead (in transit)

It could also

slow down the cooling-off of the chimney, by not allowing cooler air to enter the chimney base. This also slows infiltration of colder air into the house, increasing savings. As with any equipment of this type, dampers must be installed by a pro with proper test equipment and the know-how to do the job right.

Don't forget, even though the savings may seem small by some estimates, the ever-increasing cost of fuel will make the installation worthwhile. Burnham makes a quality boiler, so you could expect the damper installation to last a while.

If you have an oil-fired boiler, you'll have to wait till someone starts making dampers approved for oil-fired units again. Flair used to but they went out of business. Too bad- my old Flair is still working well.

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Unknown

When installing a damper

you must interface it with a control (relay or electronics) that has a fuse internally to the control that blows on the first call for heat. This will insure any future attempt to fire the equipment with out the damper attached will not occur. This in addition to the safeties already mentioned.

Dave-St Louis

Flue Dampers

Sean: Stavig Mfg. Co. manufactures flue dampers under the name of Energy Vent. They have printed information that list possible savings that might be what you are looking for. You can contact Marvin Stavig at: www.stackdampers.com
Hope this will be helpful.

St. Louis Dave

tom_59

Energy Vent

had one of these on a 1.3 million btu boiler (18" auto-damper) for the last 10-11 years. the wiring controls gave up the ghost this fall and since Stavig has switch working voltages, we declined to purchase a new one.

My experience, so far without it, is that you MIGHT gain a percent or two, but nothing like the 6-10% claims I've heard over the years. no way.

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