Co-Exist with Water Heater??

[James Ross]

I have recently acquired several new power tools for my WW hobby. My shop is a two car garage with a gas water heater in one corner. I am thinking of building plywood or MDF panels to "wall off" the heater from the adjacent tools.

The panels will not completely block air flow but will allow some space aound the sides, top and a small opening at the bottom for air flow to the burner. The panels will be used to hang hand tools such as clamps. The idea allows for moving the panels when servicing of the heater is required.

I have a DC system with temporary hose connections to the tools when being used. I am aware of possible dust explosion and hope the panels mitigate that awful possibility.

Anyone have experience with this situation? What am I missing?

Thanks

James Ross

[Greg Peterson]

I'm not expert, but I think you'll at least want or need a fire barrier on the side of the panels that face the water heater. Gypsum will work.

Is this water heater 18" above the floor? If so, your okay. If not, you'll want to get it on a stand.

Another more expensive solution, but one that would also save you money in the long and free up a lot of space now, would be to convert to a direct vent, tankless water heater. The unit mounts to the wall, freeing up valuable floor space. Direct vent system eliminates the risk of dust combustion as outside air is used for combustion purposes.

[glenn bradley]

My WH is on a step about 18" high (code?). I'm sure they weren't worried about flooding in SoCal. I have nothing around it and have no trouble. You'll find studies on the web where it was VERY difficult to create an environment where an explosion would take place. the article stated that the odds of creating such an environment outside an industrial facility were nil.

That being said (and I'm no scientist, I just read it) I would be more concerned about the panels than the boom-boom. As Greg suggested; gypsum or wonder-board and good clearance from the hot zone.

[brandon guthrie]

The mounting height has nothing to do with flooding, it is there to avoid ignition of flammable vapors that might accumulate at floor level.

[Al Willits]

Two things I'd do first is contact the manufacturer of the water heater for suggestions and then check with your local inspection dept and see what they want, don't have a lot of faith in the inspection dept but ya never know...

Al

[Bruce Wrenn]

First, look at name plate on WH and see what the distance from combustables are. I wouldn't worry too much about fire as the flame passes through the center of the water column. If heater is located in corner, why not hang two panels (on hinges), one on each wall. When service is needed, they could be swung out of the way. Could be built like a torsion bos, with 1/4" ply on inside, and pegboard on outside. You will need an opening of one square inch per thousand BTUs, both at top and bottom for combustion air.

[Chuck Lenz]

Brandon is correct, and it is code here. Gasoline vapors lay low.

[glenn bradley]

The mounting height has nothing to do with flooding, it is there to avoid ignition of flammable vapors that might accumulate at floor level.

Ahhh . . . makes sense. Thanks Brandon.

[Eugene A. Manzo III]

I would also consult the Manual or manufacturer to see what is adaquate
space for air supply to burner. This is usually larger than you might think !!

[Andrew Williams]

Also walling off the gas hot water heater will rob it of oxygen, which it needs in order to burn.

[Jeffrey Makiel]

It should be noted that about 4 or 5 years ago a requirement was adopted to make all gas fired hot water heaters sealed at the bottom. That is, the combustion air intake is via the top of the heater. The new sealed heaters have their pilot light lit by the same mechanism as an outdoor gas grill. No more access hatch at the bottom of the unit...just a clear sealed viewing port. The addition of this feature also raised the price on hot water heaters about $100.

However, if you plan to use flammable chemicals in your shop that are volatile (like contact cement or sanding laquer), a hot water heater that is raised off the floor is still not an adequate safety measure. That is, I would prefer there be no ignition sources at all within the room regardless of ventilation.

-Jeff

[Jerry Allen]

Jeff,
That only applies to mobile home heaters which cost a little more for their size and require a double walled vent.
Last year I installed a Whirlpool Flamelock propane water heater in my converted garage. The burner is sealed (compared to older units) but still draws air at the bottom. It has a mechanism and fire block screen to prevent combustion and propogation from an external fuel source.
There are a lot of bad reviews out there about this water heater about the thermocouple going out. There is a dust filter around the entire bottom and if it gets clogged, the thermocouple will over heat. It is real susceptable to lint from a clothes drier and in my case, wood dust in the shop. I check it frequently. It's external so easy to keep clean. I have not had any thermocouple problems but keep one on hand just in case.
I still try to take the same precautions when using acetone and laquer thinner, etc.
The only other thing is that I added an external 3 inch baffled vent pipe near the bottom to the outside wall. I removed the garage door and installed a double French door which is great for the cold winters and hot summers, but restricts combustion air. I imagine that if there was negative pressure in the room, it would draw air thru the vent stack, but that is probably not a good idea since it may backflow unburnt propane.
I feel that the Whirlpool Flamelock is a measure of extra protection, but fortunately can't prove that it works and really don't care to test it.

[James Ross]

Thanks for all the thoughtful input.

James