flex gas line to water heater?

homeboundOctober 19, 2007

Our old water heater is living on borrowed time (1985 Rheem), so I want to prepare for installing the next one (which will be my first). (It hasn't been flushed in the 8 years we've been here, if ever, so I'm afraid to even touch it. Sacrificial anode hasn't been checked either.

At this point, we've adopted the "wait until it fails" approach - so I hope it does so with a bit of leaky warning bells as opposed to "catastrophically". (yes, yes I know the risk, since the basement is newly finished, too. - shame on me.)

Anyway, for the new install, how do you get the union in the gas line to line up perfectly, heightwise? Can yellow flex gas line be used at all?

I suppose I can practice on our current one, since I found a small gas leak at one of the fittings (female-female coupling). It's a vertical piece fairly close to, and above the union, so I want to back it all out and redo it. As for getting it to line up again, what's the trick? Just tighten the heck out of it all, and then-some, if need be?

BTW, I have Hercules Pipe dope and rectorseal. Either is fine, right?


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Whether or not you may use a flex line would be determined by your local code. Some codes require pipe the whole way.

If you are lucky the gas input on your new water heater will be at the same height at the old one and no adjustments for length would be necessary, however in most instances it will require changing.

The code requires a "Drip Stub" at the point were the vertical drop connects to the horizontal line into the water heater gas control.

Begin by attaching a length of pipe from the gas control horizontally to the point where the line will meet the vertical drop. At the junction end of that horizontal line you will install a Tee with the side opening of the tee connected to the horizontal line to the gas control. From the bottom of the Tee you install a 3" or 4" nipple with a cap on the opposite end. This forms the required "Drip Stub". You then measure the vertical height from the top of the Tee to the union and either install the appropriate nipple or if the length is greater than 12" you will have to have a piece of pipe custom cut and threaded to length. Keep in mind that when cutting the pipe you must allow for the length of the threads in the fittings too.

My personal preference is RectorSeal for gas lines.

    Bookmark   October 19, 2007 at 10:29AM
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Thank you.

Roughly how much does one adjust the measurement for the threads? It's 1" O.D. black pipe (is that the proper terminology?

    Bookmark   October 19, 2007 at 10:46AM
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BTW, is there something that can be applied to the margin of a fitting to stop a tiny leak? (Don't think so, but I just have to ask.)

    Bookmark   October 19, 2007 at 10:50AM
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I would almost bet that if you were to measure that line with a caliper you would find it is 0.864" OD, not 1". On the other hand, ALL PIPE is defined by its internal diameter (ID).

Galvanized iron pipe, Black iron pipe, PVC pipe, CPVC pipe, Brass pipe and Bronze pipe are all made to the IPS(Iron Pipe Standard) which is defined in tables called schedules and they all have the same dimensions.

Nearly all local codes still require GAS to be run with Schedule 40 Black Iron Pipe, although both the International Residential Code and Uniform Plumbing Code also approve Galvanized Iron pipe.

Under no circumstances should you attempt to seal a leak by applying any topical material to the pipe. Disconnect the joint, clean the threads throughly, then apply new dope and reconnect the pipe.

Do not take this caution lightly. Just two nights ago there was a 3br home near hear that blew up from a propane leak. The house was completely leveled. There were four people sleeping in the house when it happened and they are now all in a burn unit with burns over 50 to 70% of their bodies and two are not expected to live. It simply is not worth the risk when working with gas lines.

    Bookmark   October 19, 2007 at 11:11PM
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