I am just thinking to install a shower in my shed which has plywood walls. The water heater I am going to get is a 5.5kw tankless from Home Depot. The manual says the heater must be installed in a place away from flammable objects. I don't think plywood is flammable, but it is uncoated wood that can be burnt. So I just want to know if it is necessary to get a metal sheet or something in between the heater and the plywood wall. Thank you very much!
Don
Should it be a fire hazard concern to mount a point-of-use tankless water heater on a plywood wall?
2018-10-20 12:56 am
回答 (8)
2018-10-20 12:59 am
Mount a small sheet of drywall/plasterboard between the heater and the plywood.
Tilebacker board /cement board would also work well.
Tilebacker board /cement board would also work well.
2018-10-20 1:49 am
I would not use a metal sheet; I would use a 5/8 thick drywall sheet over the plywood, nailed to the plywood and have it extend at least 2 feet above, below and on each side of the tankless water heater as well as on the ceiling above.
2018-10-20 1:07 am
You should be able to find installation instructions on the manufacturer's website: they will have precise specifications for what you need to do.
Worst case, you'll have to install a layer or two of fire rated ("Type-X") gypsum board over the plywood: not a big deal.
Check the electrical requirements, while you're at it. 5.5 kW isn't much for a house, but may exceed what your shed is wired for.
Worst case, you'll have to install a layer or two of fire rated ("Type-X") gypsum board over the plywood: not a big deal.
Check the electrical requirements, while you're at it. 5.5 kW isn't much for a house, but may exceed what your shed is wired for.
2018-10-20 1:00 am
Thats how i put mine in 4 years ago, no problems
2018-10-24 5:18 am
Plywood is combustible, which is slightly less dangerous than "flammable". So are the wooden studs in the wall (if it's that sort of wall. However, in all the installation manuals I have ever seen for 3.5kw to 28 kw electric water heaters, they are NOT concerned about combustible mounting surfaces, but rather clearances around the front, top and sides (e.g, 12 inches from combustibles).
Wood is combustible, even if encapsulated in gypsum or ceramic tile. However, that would only be a concern when installing a much larger source of heat (furnace, fireplace, boiler, wood stove) requiring a 36-inch clearance from "combustible structure", unless certified otherwise or the combustibles are shielded (INCLUDING an airspace), per NFPA codes. Been to many house fires caused by insufficient stove/connector clearances, which may take 15 years to cause a problem, but you'd better hope someone's around when it does...
Were you inclined to install a "shield" of some sort, you could certainly mount the heater to a piece of cement board ("tile backer") or metal or other non-combustible material, and then mount that to the wall with one-inch stand-offs (e.g., screws sleeved with a one-inch length of copper tubing). That way, you will have at least tripled the convection flow of heat away from the mounted side of the heater, where air will naturally flow into the space, warm up, rise, and carry the heat with it.
Wood is combustible, even if encapsulated in gypsum or ceramic tile. However, that would only be a concern when installing a much larger source of heat (furnace, fireplace, boiler, wood stove) requiring a 36-inch clearance from "combustible structure", unless certified otherwise or the combustibles are shielded (INCLUDING an airspace), per NFPA codes. Been to many house fires caused by insufficient stove/connector clearances, which may take 15 years to cause a problem, but you'd better hope someone's around when it does...
Were you inclined to install a "shield" of some sort, you could certainly mount the heater to a piece of cement board ("tile backer") or metal or other non-combustible material, and then mount that to the wall with one-inch stand-offs (e.g., screws sleeved with a one-inch length of copper tubing). That way, you will have at least tripled the convection flow of heat away from the mounted side of the heater, where air will naturally flow into the space, warm up, rise, and carry the heat with it.
參考: fire inspector, engineer
2018-10-21 4:45 am
Concrete board...it's cheap and it doesn't burn...!!
2018-10-20 2:46 am
A properly functioning tankless water heater isn't even warm to the touch. If the shell gets anywhere CLOSE to hot enough to be a fire hazard, it doesn't matter what it is mounted on.
2018-10-20 1:02 am
It’s wood so of course it’ll burn.
If you’re not 100% sure then you play it safe. So use a metal sheet or something that can absorb heat.
If you’re not 100% sure then you play it safe. So use a metal sheet or something that can absorb heat.
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