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Old 05-29-2013, 11:00 AM   #1
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Gas Water Heater Combustion Air


I have a gas water heater installed in a second story closet. It draws its combustion air from my attic through PVC pipe going into the attic. I am about to get 14" of additional blown in insulation added, which will cover the pvc in their current arrangement.

What is the best way to ensure I get proper combustion air? Should I avoid getting any blow in in insulation on the ceiling above the water heaters closet at all? Extend the pipes up? one contractor mentioned treating the pipes like can lights and using a cylindrical wire cage to keep the insulation away from them.

Follow up question, if I maintain proper venting to the attic, can I tightly seal and insulate the closet door? Right now its just a standard interior door, no grate through it and no door seals.
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Old 05-29-2013, 11:18 AM   #2
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Gas Water Heater Combustion Air


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Originally Posted by BikerAggie View Post
I have a gas water heater installed in a second story closet.
It draws its combustion air from my attic through PVC pipe going into the attic. ...
I am about to get 14" of additional blown in insulation added, which will cover the pvc in their current arrangement.

Should I ...Extend the pipes up?
Sounds like the simplest solution to me.

Quote:
Follow up question, if I maintain (combustion air intake) from the attic
can I tightly seal and insulate the closet door?
I wouldn't.

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Old 05-29-2013, 12:28 PM   #3
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Gas Water Heater Combustion Air


Because that is your existing combustion air, does not mean it is adequet.

Normally for gas fired appliances, you need a circulating type system, such as a high and low vent. Furthermore, there are complicated ways to figure / calculate sufficient combustion air. Probably should have an hvac man double check it.

Your unsealed door may be providing that circulation in part, although not by design.

If you can ascertain that you have adequest combustion air through designed sources, then yes I would seal the door up. In effect, that closet becomes almost an outside area. You may want a WH insulation blanket also.


EDIT: Just looked at your picture again. Looks like you may have your circulating high/low venting. And maybe you are fine... if you don't know for certain, I would still have it checked

As far as extending the one vent you have, combustion air calculations take into account pipe size and length among many other things.... but I doubt extending it 14" would have a material effect on those calculations.
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Old 05-29-2013, 02:58 PM   #4
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Gas Water Heater Combustion Air


Put an open louver in the door. Oh, and you need a yellow range connector that is a little longer than that one.
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Old 05-29-2013, 04:44 PM   #5
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Gas Water Heater Combustion Air


I don't know if thats proper fresh air returns under your local codes but under our its a no go and a violation must pull air from the exterior of the home not the Attic should you have a flew / burner problem you would just be pumping in more Carbon monoxide in to the home via the attic, also correct that gas line and install, have a pro give you the green light on that complete install, not meeting code from what i can see.
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Old 05-30-2013, 09:29 AM   #6
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Gas Water Heater Combustion Air


Thanks for your responses everybody. I have one follow up question, whats the potential harm in the (obviously) long gas flex line?
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Old 06-02-2013, 07:30 AM   #7
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Gas Water Heater Combustion Air


Yes, extend the PVC pipes as long as this setup meets code.

One thing ton consider also is the potential for this setup to pull CO into the living space. if the exhaust is not sealed properly.

Last edited by handy man88; 06-02-2013 at 07:33 AM.
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Old 06-02-2013, 08:34 AM   #8
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Gas Water Heater Combustion Air


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Originally Posted by BikerAggie View Post
Thanks for your responses everybody. I have one follow up question, whats the potential harm in the (obviously) long gas flex line?

Biker... Caveat, I'm a GC... not a HVAC code expert.... but apart from being messy and not looking workmanlike, I don't think per se their is a problem with your long flex line.

I believe there may be restrictions as to total length and going thru walls, but AFAIK, I don't think there is a problem in your application.

EDIT: Just as additional info, and I can't seein your picture very well, you do need a gas shutoff and a drip leg right before your flex line. (If you did not have those installed, it might be an indication that your installer was not also compliant with your combustion air calculations)

Maybe, someone more expert /specialized will correct / elaborate or confirm.

Good luck

Peter
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Old 06-02-2013, 08:37 AM   #9
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Gas Water Heater Combustion Air


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Biker... Caveat, I'm a GC... not a HVAC code expert.... but apart from being messy and not looking workmanlike, I don't think per se their is a problem with your long flex line.

I believe there may be restrictions as to total length and going thru walls, but AFAIK, I don't think there is a problem in your application.

Maybe, someone more expert /specialized will correct / elaborate or confirm.

Good luck

Peter
I'm not an expert on flex gas lines, but if it were me, I'd try to make it neat with a few loops. It be interesting why a flex gas line would be sold at that length if it's not within code, but maybe for the looping purposes.
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Old 06-03-2013, 04:52 PM   #10
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Gas Water Heater Combustion Air


They sell flex lines from about 12" to 48" long... theoretically longer if you care to include the gastite style of flex tubing which can be cut to pretty much any length.

While there is no code reason that I am aware of to not have the flex line that long, it doesn't look nice and neat. As long as the gas pressure is where it should be and the overall length of the house gas piping can handle the BTU requirements of the heater, then it is fine. If you do not have a drip leg AKA sediment trap on the water heater I would suggest strongly that you have one installed. Unattended appliances require drip legs unless otherwise indicated. Refer to your water heater installation manual for the gas piping requirements.

This is one of those times when you could say, "Why was it fine without it for all this time?" The answer is: It isn't fine the way it is if a dripleg was required originally.
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Old 06-03-2013, 07:02 PM   #11
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They sell flex lines from about 12" to 48" long... theoretically longer if you care to include the gastite style of flex tubing which can be cut to pretty much any length.

While there is no code reason that I am aware of to not have the flex line that long, it doesn't look nice and neat. As long as the gas pressure is where it should be and the overall length of the house gas piping can handle the BTU requirements of the heater, then it is fine. If you do not have a drip leg AKA sediment trap on the water heater I would suggest strongly that you have one installed. Unattended appliances require drip legs unless otherwise indicated. Refer to your water heater installation manual for the gas piping requirements.

This is one of those times when you could say, "Why was it fine without it for all this time?" The answer is: It isn't fine the way it is if a dripleg was required originally.
could a loop in the flex line serve as the droop?
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Old 06-03-2013, 07:29 PM   #12
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could a loop in the flex line serve as the droop?
No. A drip leg is intended to change the direction in the flow of the gas so that any sediment can drop down into the pipe and the gas goes freely into the appliance.
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Old 06-03-2013, 07:36 PM   #13
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No. A drip leg is intended to change the direction in the flow of the gas so that any sediment can drop down into the pipe and the gas goes freely into the appliance.
Yes, I see that in my iron pipe. Does it ever need to be cleaned?
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Old 06-03-2013, 08:23 PM   #14
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could a loop in the flex line serve as the droop?
Yeah, it can serve as the droop, it just can't serve as the drip
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Old 06-03-2013, 08:28 PM   #15
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Yes, I see that in my iron pipe. Does it ever need to be cleaned?
Theoretically yes.... but not really. I've never cleaned one in my life. If you take one apart (replumbing) maybe you'll find a little sediment.

I've lived in my present home with two furnaces for almost 30 years... never an issue.

Not sure, but I think code used to be like a 6" drop, now maybe 8"

Maybe in different areas, someone has had a different experience.

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