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WH on garage floor

Plumber replaced a gas water heater in a customer's house. Put it on the garage floor. Told her that the new design means they no longer need to be 18" up. That true? 


  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    I will tell you what I know.

    I am just a homeowner, and I have a mod-con in my garage. I got an installation manual for it of fthe web and it said if it is located in a garage, it must be 18 inches up from the floor. My old oil fired boiler was flat on the floor. So when my former contractor was installing it, they put the new one on the floor. I asked why they were doing that since the Installation manual said specifically that it had to be 18 inches up. The explanation was that the boiler had a sealed combustion system (true) that got its air from outside and exhausted directly to the outside (also true), so any combustable vapors in the garage would not be sucked into the boiler itself. Furthermore, they said that the air intake to the burner was actually over 18 inches from the floor (it may be a little less than that). I have my doubts about my former contractor. I do not think it is much of a safety problem because their explanations are mostly true. Unless the gasket between the front door of the boiler and the rest of it leak rapidly, I would not expect much gasoline vapor to get in there. When they were done, the inspectors did not have a problem with it. But that inspector also allowed an ungrounded unbonded piece of CSST gas pipe. But even though it passed, I bet is is not according to code.
  • Ironman
    Ironman Member Posts: 7,379
    edited April 2011
    Not True

    Unless it's direct vent, the burner must be 18 in off the floor. I don't have time at the moment to pull up the code reference, but we covered that in gas code class last week.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • billtwocase
    billtwocase Member Posts: 2,385
    or if not

    you can build a vapor barrier around it with blocks and cement, but 18"  off the floor is the norm.
  • meplumber
    meplumber Member Posts: 678
    NFPA 54 tells us that the appliance installed in a Residential garage must be 18 inches off the floor unless specifically listed as 'Flammable Vapor Ignition Resistant."

    There is a huge difference in a Residential Garage and a Repair Garage where the requirements a long and distinguished.
  • Robert O'Connor_12
    Robert O'Connor_12 Member Posts: 728
    Elevation of ignition source

    Elevation of the ignition source is not required for appliances that are listed as flammable vapor ignition resistant (FVIR).

    Robert O'Connor/NJ
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Mine is direct vent, but

    Mine is direct vent, but the installation manual says it must be 18" off the garage floor. (Weil McLain Ultra 3.) Are they being overcautious, or do they know something that I do not (easily possible).
  • John Mills_5
    John Mills_5 Member Posts: 952

    for the information. At least the plumber was right about that. Now his 3x4" flue transition which was just a 4" over a 3" and mashed down and his PVC pop off piping...
This discussion has been closed.