Water Heaters - Gas Hot Water Tank Vented correctly?
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911pyro
02-23-06, 12:53 PM
The good: Had the sellers of the house I purchased install a new hot water tank before taking possession.
The bad: Think they installed the tank themselves and not convinced it is vented correctly.
The tank vents into a metal pipe that runs up through ceiling (horizontally), then up (vertically) into the attic and out the roof. Problem is that the pipe coming out of the ceiling and into the attic is PVC which became deformed and separated due to the high heat of the tank exhaust.
I assume the tank, which I believe is a direct vent, isn't vented correctly. Would it be best to:
1) replace all of the current pipe with metal pipe, which wouldn't be easy as the attic is actually a very small because it's vaulted
2) try and vent it out a wall that is about 5' away
3) or install a correct hot water tank (assuming there is one for that mess of pipe)
Thanks in advance for your advice,
Neil
The bad: Think they installed the tank themselves and not convinced it is vented correctly.
The tank vents into a metal pipe that runs up through ceiling (horizontally), then up (vertically) into the attic and out the roof. Problem is that the pipe coming out of the ceiling and into the attic is PVC which became deformed and separated due to the high heat of the tank exhaust.
I assume the tank, which I believe is a direct vent, isn't vented correctly. Would it be best to:
1) replace all of the current pipe with metal pipe, which wouldn't be easy as the attic is actually a very small because it's vaulted
2) try and vent it out a wall that is about 5' away
3) or install a correct hot water tank (assuming there is one for that mess of pipe)
Thanks in advance for your advice,
Neil
911pyro
02-24-06, 10:39 AM
Perhaps someone could offer some advice on direct venting the 40 gallon tank. Questions I can think of off hand are:
1. I assume I should use metal pipe, but of what diameter?
2. I read that you need an 8" whole in the wall, is this really necessary and why?
3. Should I try to maintain a slight verticle slop (ie. 1/4" per foot) in the pipe, or is it not necessary?
Any advice would be greatly appreciated. Thanks,
Neil
1. I assume I should use metal pipe, but of what diameter?
2. I read that you need an 8" whole in the wall, is this really necessary and why?
3. Should I try to maintain a slight verticle slop (ie. 1/4" per foot) in the pipe, or is it not necessary?
Any advice would be greatly appreciated. Thanks,
Neil
hankhill6018
02-24-06, 05:05 PM
Chances are you're water heater is not a direct vent but a standard atmospheric vent water heater. A direct vent water heater will draw the combustion air from the outdoors as well as the exhaust. Posting the make and model of the heater will be helpful in figuring out the variety.
With that said....
If it is of the standard vent variety, there should not be any PVC, CPVC, ABS or any other type of plastic pipe used in any section of the vent. In fact, nothing short of "B Vent" (double walled) pipe should be used with a 3 inch diameter (for 30 and 40 gallon heaters). Pitch of any "horizontal" runs should be a minimum of 1/4 inch per foot.
I've never heard of a 8 inch requirement for the size of the hole in the wall but again, it could be dependent of the circumstances. There is a minimum clearance requirement for B vent from combustibles is 1 inch, which means, for 3 inch vent pipe, you will need a five inch hole.
As far as your two options:
To keep the existing water heater I would correct the vent pipe in the attic. Going through the wall that is five feet away could be done, but, you would still have to vent it up above the roof. The down side of this option is excessive condensation could accumilate in the pipe causing corrosion.
You could replace the water heater with a power vent type. The pro's is you can scrap all the existing pipe and just vent it out through the exterior wall. It is not required to go up to the roof. This type of water heater can be vented with PVC pipe two or three inch diameter. The down side is you have to replace the whole heater.
If your existing heater venting is separated, I would recommend you stop using the heater until the proper repairs can me made. The exhaust from the water heater is should not be allowed to enter the house (even in the attic) as it could create health issues.
With that said....
If it is of the standard vent variety, there should not be any PVC, CPVC, ABS or any other type of plastic pipe used in any section of the vent. In fact, nothing short of "B Vent" (double walled) pipe should be used with a 3 inch diameter (for 30 and 40 gallon heaters). Pitch of any "horizontal" runs should be a minimum of 1/4 inch per foot.
I've never heard of a 8 inch requirement for the size of the hole in the wall but again, it could be dependent of the circumstances. There is a minimum clearance requirement for B vent from combustibles is 1 inch, which means, for 3 inch vent pipe, you will need a five inch hole.
As far as your two options:
To keep the existing water heater I would correct the vent pipe in the attic. Going through the wall that is five feet away could be done, but, you would still have to vent it up above the roof. The down side of this option is excessive condensation could accumilate in the pipe causing corrosion.
You could replace the water heater with a power vent type. The pro's is you can scrap all the existing pipe and just vent it out through the exterior wall. It is not required to go up to the roof. This type of water heater can be vented with PVC pipe two or three inch diameter. The down side is you have to replace the whole heater.
If your existing heater venting is separated, I would recommend you stop using the heater until the proper repairs can me made. The exhaust from the water heater is should not be allowed to enter the house (even in the attic) as it could create health issues.