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Stack damper with a new WM LGB8

I thought all LGB boilers come with lo/hi/lo gas valve train..... Maybe only on water, but yes get the damper, but to they make them that big? Never seen them on larger boiler and some said they are not worth the cost over saving on gas....but with the rising gas cost...


  • mike hurley_2
    mike hurley_2 Member Posts: 4
    Stack damper & lo-hi-lo for a new WM LGB 8

    Hi, I am having a new steam boiler installed, two contractors have measured radiators and both recommend a Weil Mclain LGB 8. (The house is 6600 sq ft + basement, built in 1930)
    The contractor seems reluctant to install a stack damper, saying they don't come with the bigger boilers.
    This is a lot of money for me, so I want to get as much efficiency as possible.
    1. Should I insist he install a stack damper or are there valid reasons not to?
    2. Any other thoughts on maximizing efficiency -- I also want him to connect for lo-high-lo firing.(based on what I have read here) Is that very involved? How much extra should it cost?
  • Dave_4
    Dave_4 Member Posts: 1,405
    Get both!

    The W/M damper is an option and well worth the added ~$300 it costs. It increases AFUE by almost 10%!

    The step-mod feature is very nice as well. It requires compatible gas train(s) and a simple second pressuretrol. For accuracy, I'd also invest in a vaporstat.

    The step-mod feature runs around $300-500 depending on W/M's latest pricing and the vaporstat could run 100 more than the "plain-jane" you get with the boiler. The step mod gas train already has the second pressuretrol included in the option pricing.

    You are probably required to have a high limit, manual reset control as well - making the fully functional system with three pressuretrols/vaporstats.

    The contractor who can explain the advantages of the more efficient options and suggests adding them to the base quote would move to the top of my "best" guy list. The guy who is not inclined to get into the more efficient options would drop off my list of desireable contractors...

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  • I assume by stack damper

    we are talking about a vent damper? If not then my apologies perhaps there is some new device I am not aware of. If so the savings is only about 3% depending on whether the system is spark ignited or standing pilot. Vent dampers also have their problems from time to time so service problems should be a consideration.
  • RonWHC
    RonWHC Member Posts: 232
    Large percentage of

    service calls on storage type commercial water heaters, in our area, are for failed vent dampers. Many installers routinely disconnect them after installation. I believe Weil's damper is made by the same company that supplies dampers to most heater manufacturers.

    Tim was being diplomatic.
  • Steamhead (in transit)
    Savings depend on

    what type of chimney the boiler is hooked up to. Since it's a steam system, it's reasonable to assume the chimney was designed with a very strong draft capability that can pull pets and small children up to the roof. On these, a stack damper can save a lot.

    Also, as far as I know, all W-M LGB boilers come with lo-hi-lo gas trains. Many installers don't hook them up though.

    The trouble with the LGB, however, is it's an atmospheric boiler in which the flame is entirely below the cast-iron sections. This type loses much heat from the base when running. The alternative is a wet-base boiler with a power gas burner in it. This type completely surrounds the flame with water-backed cast-iron and so is a bit more efficient. Plus, if the gas company gets too greedy you can switch a wet-base unit to oil by having a pro change the burner. And the wet-base boiler would not need a stack damper.

    Since your potential installers like W-M boilers, the 7-section 80-series boiler (7-80) has about the same ratings as the LGB-8. W-M can supply it with a Gordon-Piatt, Power-Flame or Webster power gas burner, or gas-oil burner if you wish.

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