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Gas water heaters

E. Burns

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Hi Ellen,

Unless you've got conditions there that are favorable for backdrafting, I think in this case it is probably caused simply by the fact that the puff shield isn't installed correctly and the secondary puff shield is missing.

That's a pretty Rube Goldberg arrangement of soft copper pipe feeding that guy. I don't see a drip leg there and it looks like they've had to use an adapter to up-size it to the control valve, which is not permitted. Check the BTU/HR requirement of the appliance to ensure that tubing that small can provide sufficient flow to that water heater to meet the BTU/HR requirements.

Is the shutoff valve within your state's designated distance from the appliance? Also, the picture is a little fuzzy in my monotor. Is that a concrete floor? If so, was that copper in contact with the concrete?(Also a no-no.)



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If it was not just evidence of a PAST (repaired) problem, I would write;

"This photo shows the evidence of flame roll out. I measured a XX PPM CO reading spilling into the house. This roll out can be caused by improper venting, a down draft condition, a problem with the tank itself or an obstruction in the flue or chimney. This roll out is not only a fire risk, dangerous (deadly) fumes are entering the dwelling. I have turned the gas to the appliance off. Call a licensed plumber or heating contractor to correct the problem and restore service."

Yes I know that many will jump all over that approach, but nobody gets hurt this way. I would rather be hauled into court for over reacting than failure to act at all.


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Thanks Mike,

I will show your response to Ron.

We got the drip leg.

I don't know if Ron noticed the adapter.

The air handler next to the water heater was sucking alot of air, full of dust at the unsealed seams.

On another note: The one inch clearance for the B vent to combustibles. Does the ASTM standard consider drywall a combustible?

NONCOMBUSTIBLE BUILDING MATERIAL. A material which meets either of the following requirements:

1. Materials which pass the test procedure set forth in ASTM E 136.

2. Materials having a structural base of noncombustible materials as defined in 1, with a surfacing not more than 1/8 inch (3.17 mm) thick which has a flamespread rating not greater than 50 when tested in accordance with ASTM E 84.

The term noncombustible does not apply to the flamespread characteristics of interior finish or trim materials. A material shall not be classed as noncombustible which is subject to increase in combustibility or flamespread rating beyond the limits herein established through the effects of age, moisture or

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Originally posted by E. Burns

What do you guys report when you see the flame roll out condition? I have enclosed a photo.

What conditions are typically attributed to this besides improper venting?

As far as gas appliances in our area we don't run into that much.

Download Attachment:

Ellen, what I see there may or may not be flame rollout. I reserve that term for the "roll out" that may happen with ignition. That's where flame actually rolls out, and is rare when the shields are in place.

What I'm seeing in the photo is simply typical of "spillage" - when combustion gases exit at the burner port. Over time the heat scorches the paint, without actual flame rolling out. (The term applies to gas furnaces as well.) This is distinguished from "backdrafting" which I prefer to limit to what happens at the draft hood. When it's 'spillage' at the burner port, it's usually due to a clogged internal chimney. Or maybe even a collapsed one, if the unit is very old. It can also be due to excess gas pressure. One of the two manufacturers of thermostat/valves makes one with a small green cap on the top. Under that cap is a gas pressure adjustment screw. Backing off the pressure often cures this.

-David Lee in VA

icon_photo.gif P1010029.jpg

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