proper elevation of gas hot water heater in utility room?

brainfog

My New Year day party was to replace the gas water heater - which I placed directly on the floor next to the gas furnace (directly on the floor before I purchased the house). I've since learned that the lowest point of ignition for these appliances should be >=18" above the floor - at least in the garage.

They're located in a small utility room (6x6' ?) with a fire door. The garage is 20 feet away - through 3 doors.

The previous gas water heater was 9" shorter and on top of a wobbly cinder block. I figure it was elevated (only 8") because the house water supply pipes were in the way. I moved them.

I'm in the state of MA - given that its in a specialized room with another ignition source 2" from the floor - should I relocate the water heater? Is it out of code to leave it on the ground? Adding the needed 15" isn't possible due to only 12" being available to the flue pipe. After the initial rise, there is a about 4' of horizontal run - with a slight elevation. If I raise too much then I expect there is a real CO hazard.

Possibly I need to return the DHW and get a short? In this case, I still can't get the 15" and also have a proper initial rise of exhausted.

I've attached some photos if they're of interest.

TIA.
Chris


Images are here since they don't seem to show up inline :
http://tinyurl.com/z8fdoj4

Fred

Are you sure that requirement isn't for combustible floors (i.e. wood) or is that a requirement in a garage due to other potentially combustible gases/fumes ?

Jamie Hall

I don't know the MA code on these things. I do have a couple of comments, though, sort of in the "good practice" range. First, I'd like to see it a couple of inches higher, but mostly so that if you get a water leak or spill in there it doesn't get into the burners.

Second, a 6' x 6' room? Make darn sure you have enough combustion air in there! And a CO detector.

MikeSpeed6030

Will you have enough room to put a bucket under the water heater drain valve for routine draining?

Please download the manufacturer's installation instructions and follow them.

I wonder about the flexible gas line going to the furnace. Somehow, I had thought that they were only to be used for an appliance that might need to be slid out for maintenance, such as a clothes dryer - otherwise solid piping. Local codes prevail, of course.

Bob Bona_4

Crying shame you didn't install an indirect fired waterheater and eliminate all flue issues regarding that, as well as greatly reducing the need for combustion air in the space. Next time, maybe about 5-7 years from now . The garage code doesn't apply here, but it's always nice to have the appliances up on 2" or more block to preserve the base.

brainfog

Hi Jamie,
The base of the unit is actually elevated 2.5" due to its built in legs and a major water leak (well pump / 5 gpm) would likely drain out of the room But raising the unit a bit more seems reasonable. I have some 6x6x2" bricks that could work.

The room is small. I can only say I didn't design it. I assume it was all approved when the house was built. But maybe then there was no gas and some other yahoo packed a 40KBUT HWH and 250KBTU boiler in there.

Openings are about 16 sq in under the door (~1/2" gap). At the top there there is no ceiling so there is the space between 3 rafters. This of course means that fire from the room can spread quickly!

There is a 2yo CO detector and its never registered anything. I tested it once in a box w/candle.

I also found the unit has a FV sensor that mounts under the unit - so possibly it is intended to be mounted as I've done it. I reviewed the manual and it actually doesn't say.

Thank you.

Jamie Hall said:

I don't know the MA code on these things. I do have a couple of comments, though, sort of in the "good practice" range. First, I'd like to see it a couple of inches higher, but mostly so that if you get a water leak or spill in there it doesn't get into the burners.

Second, a 6' x 6' room? Make darn sure you have enough combustion air in there! And a CO detector.

brainfog

Hi Bob,
If understand, you're suggesting that I use the furnace boiler as the heat source for the DHW? I've considered this but a proper indirect tank is expensive and seems to require expense stainless circulating pump - and expense flat plate heat-exchange.

I've been wondering however if I could use a vertical tube water-water heat exchanger that self pumps due to difference in water density - heated from the furnace boiler loop.

Possibly you could possibly point me to one?

Thank you.

Bob Bona said:

Crying shame you didn't install an indirect fired waterheater and eliminate all flue issues regarding that, as well as greatly reducing the need for combustion air in the space. Next time, maybe about 5-7 years from now . The garage code doesn't apply here, but it's always nice to have the appliances up on 2" or more block to preserve the base.

Bob Bona_4

You have steam heat?

brainfog

Hi Mike,
The unit actually is 2.5" off the ground due to its built in legs. But yes draining could be tricky. I'd probably use a shallow pan and sump pump for the last bit.

The instructions aren't so clear on the matter of elevation. I re-reviewed them and the 18" requirement isn't there (the illustrations appear to show ground mounting). Likely I found it when reading something else online.

The furnace is on solid pipe all the way. The flex pipe is the previous owners kludge to extend the gas line to another appliance in another room. It actually unconnected.

The HWH I replaced also used flex pipe - so I just copied it. But if it is required I can switch to solid. However because movement of the tank is *possible* (someone falls into it or if its drained) it actually seems solid pipe is more likely to be damaged. OTOH - flex pipe gets damaged if I drop something into it. Guess I'm going to solid.

Thank you.

MikeSpeed6030 said:

Will you have enough room to put a bucket under the water heater drain valve for routine draining?

Please download the manufacturer's installation instructions and follow them.

I wonder about the flexible gas line going to the furnace. Somehow, I had thought that they were only to be used for an appliance that might need to be slid out for maintenance, such as a clothes dryer - otherwise solid piping. Local codes prevail, of course.

brainfog

Bob Bona said:

You have steam heat?

Its hot water. I guess its called a hydronic boiler?

Robert O'Connor_12

If the new heater has FVIR,
It can sit right on the floor.
Having it up on some blocks never hurts if the area doesn't have a drain and typically floods
As others have said, check your installation instructions and local codes.

Robert O'Connor/NJ

Bob Bona_4

Hot water, then next time around you can pipe another zone off the boiler, you don't need the heat exchanger/stainless pump stuff like you should do with steam condensate water heating.