OT Need advice on plumbing new water heater to existing solid copper lines


Sorry to abuse this group - but I've yet to find another that has the right "mentality" for doing things right. Something about a WW that implies a certain character trait for striving for perfection, albeit with a certain degree of cost consciousness.
ok.. onto the question
I am replacing my water heater. It's taller than the old one, so I need to make some plumbing changes. The flue should be fine, and I plan to use the existing gas line (black pipe into the heater - with a short run of new flex - then into more black pipe (with a shutoff). I'll wipe off the threads and apply a new batch of dope.
For the water lines, the old one had solid copper down to the heater, with a compression fitting of sorts right at the heater. I don't believe I can salvage that fitting. The new heater has male threads, 3/4" I believe.
Should I plumb with solid copper? The most challenging solution? Or should I use some form of flex? Presumably I'd sweat on a male thread connector to my solid copper and then use a flex line between solid and heater. Is there a preference on flex? At HD, I see corrugated copper and some form of stainless steel. The stainless can be "pinched" and would seem to be "thinner" which to me implies more likely to fail.
Any help much appreciated.
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_IF_ that male-thread on the heater is copper, then 100% solid copper *is* the way to go. Appropriate disconnect fittings are available -- may have to check a _real_ hardware / plumbing-supply store -- or you back up to the first elbow, and go from there, with a piece that has a female thread sweated onto the end.
Note: unless it is a *big* water heater, it's probably a quote 1/2" NPT unquote fitting, which _is_ close to 3/4" outside diameter.
If the heater fitting is anything other than copper, a "dielectric coupling" is an _absolute_ requirement. You *don't* do metal-to-metal fittings on water-carrying plumbing where the dissimilar metals come into contact. Unless you want the joints to burst within a few years, that is. <grin>
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Robert Bonomi wrote:

Don't you love it when you read things like this *after* finishing a job?
My nipples were "heat traps" I think, and they were galvanized steel with some sort of blue plastic stuff at the end. I used flex because the new heater has a dramatically larger footprint than the original, owing to the substantially improved insulation on the newer model. It would be a really bitchy problem to solve with rigid pipe.
The flex has brass on either end, with that funky corrugated copper. So now I've got copper to brass (not sure if the tin and whatnots mixed into brass cause galvanic problems) and copper to brass/zinc/iron with some rubber and plastic mixed in. Could be a mess. The blue plastic bits on the "heat traps" might actually perform the function of some kind of of dielectric junction, but I heard one of them make squeaky noises on the last turn, which probably means I smushed through the plastic, and have brass on galvanized contact.
OTOH, the old water heater had copper screwed directly onto some kind of ferrous material, and it lasted for 30 years. I guess I'll worry about it if it ever leaks.
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Did we meet once at "The Foxy Lady" ? Did I ever give you a dollar bill?
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A few thoughts on your installation... Flex line is a poor choice. Aside from being expensive, it it unreliable. 1/2" copper is very easy to use; almost foolproof. 3/4", which you probably have, is more challenging. Unless you can find someone experience to help you, 3/4" might be too much to bit off for your first plumbing project. The water heater I bought at HD had a big cautionary statement that you will damage the heater by soldering the nipples on; a union is required. You might want to check yours for that. (I didn't bother reading the instructions until after I was done with the installation, and my soldered nipples were fine, but that's another story.)
Good luck in whatever you do.
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1) Why is it a poor choice? Some building codes may in fact require it, for example in earthquake prone territory.
2) Upon what evidence do you base your assertion regarding the unreliability of flex line?

In particular, a di-electric union is required. This is required to prevent electrolysis from prematurely causing heater failure.
scott
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nospam snipped-for-privacy@mesanetworks.net wrote:

In addition to what other posters have written, I'd like to add this: Check local codes. In earthquake-prone areas, they may *require* flex connections for the water *and* gas lines. Other places may *prohibit* one or the other, or both.
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
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Some local regulations require a licensed gas fitter to do the gas connection. Frankly, for the matter of a few dollars, best to let the pro do the connection and be safe. Likewise, the same gent can deal with the Flue, and test for Carbon Monoxide afterwards.
This is one of those jobs that has legal issues, liability issues and your home owners insurance coverage could be involved.
On Tue, 15 Mar 2005 00:25:25 -0700, nospam snipped-for-privacy@mesanetworks.net wrote:

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nospam snipped-for-privacy@mesanetworks.net wrote:

Be careful to dot all the "i"s and cross all the "t"s legally with gas. If something goes wrong and the house blows up and somebody gets killed and you haven't covered all the bases then you might end up going up for manslaughter--it's an unlikely scenario I admit but you know Murphy's Law.
First, check your local codes and make sure that they actually allow you to work on gas. Then see what they say--among other things anything upstream of the last cutoff may need to be pressure-tested--not difficult if you've got the tools and know what you're doing but if you're never seen it done before it might be a good idea to hire a gasfitter to do it the first time and watch how he does it.
There should be a shutoff _before_ any flex--if the pipe leaks it's most likely to be in the flex and if there is no shutoff upstream of the flex then you have to turn the gas off at the meter until you get a chance to change out the flex. Treat flex with the same degree of confidence that you treat the hoses on a washing machine--only trust it so far. But you should not need it with a water heater unless there is a serious accessibility problem, and if there is then it would be better to address the problem so that you can use solid pipe.

Unless there is a compelling reason not to, yes.

See comments with regard to flexible gas pipe. Unless there's a serious accessibility problem there's no reason to use flexible water pipe with a water heater--it doesn't get moved, it doesn't vibrate, there's no need for it. If you need to offset the line a little there is bendable copper that works fine. Others have commented on the issue of dissimilar metals, I'll echo what they say--there are purpose made fittings for connecting dissimilar metals in plumbing that provide isolation and prevent a galvanic reaction. Use one if you need to.

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--John
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Is flex even allowed? Used to be that it was allowed only on ranges, but not stationary appliances. That was when I lived in Philly but other regions may be different.

You get better flow with the hollow stuff.
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wrote:

-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
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Edwin Pawlowski wrote:

I should have included that _if_ flex is even allowed by the code. In some parts of the country the code can be pretty lax if there is one at all.

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the heater in California.
scott
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Scott Lurndal wrote:

Required or allowed? Seems to me that if it's required it should also be required for furnaces, entrances, and various other places where more movement and stress are expected than at the water heater connection.

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<snip>

I am not a contractor, but have owned and seen a lot of properties, in the SF Bay Area. Flex is used in most or all of those applications you named, such that I don't recall seeing anything else here.
Earthquake, expansive soils, etc. And progressive building codes. Tank bracing is specified. So are quick shut-off valves. Fire after a quake is a much bigger problem than the quake itself, both in property damage and in danger to occupants. And the use of natural gas is almost universal.
What works for you in your areas, I don't know. Follow _those_ guidelines. For example, we don't have to worry about frost heave or road salt corrosion.
Patriarch
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nospam snipped-for-privacy@mesanetworks.net writes:

So, once you've turned the gas off at the stopcock and replaced the flex-gas line, you turn the gas back on and it leaks, what will you do? You do know how to check for leaks, right? (Hint, don't use a match).
Note that a gas stopcock uses a special grease to prevent leakage around the valve. It is a good idea to replace this grease when you replace your flex line, especially if the valve hasn't been turned in years, as if often the case. The valve can be disassembled, apply the specialized grease liberally and reassemble the valve. If you don't feel comfortable with this, just buy a new stopcock.
You may be able to call your gas supplier for a free hookup and leak check.
scott
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I've repalced all my copper with PVC. There are fittings to switch between PVC / copper / steel. Mark

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update on what was done
I called town hall. A permit and inspection is required. I called the inspector, flex for water is ok. The county does not require a permit/inspection for replacing a water heater, but the city does.
I removed the old heater and replaced with a new one. Same gallonage, but different dimensions (taller, fatter).
I had to cut away some copper for the water. I sweated in a male threaded insert to the solid copper and joined that to the heater with corrugated copper flex. I had to bend the flex into a S shape. If the S shape had been bigger, I guess that would have served as a heat trap. Supposedly the heater has a diaelectric fitting. The copper flex has a "rubber hose washer" inside it. Not exactly comforting. I could probably sweat in solid copper if I have to. If I do redo this, I will also redo some of the solid copper leading to the heater. It's been jogged left and right several times that a) looks bad and b) I prefer simplicity.
For the gas line, I disassembled the old heater's flex (which as only a few months old. It was put there by the furnace installer who moved the heater when the new furnace was installed). The gas flex joined solid black piping on the supply side with solid black piping on the heater side also. I disassembled the necessary black pipe from the old heater, cleaned the threads and inspected the pipe. It look OK for re-use. I re-assembled the gasline -- blackpipe and flex using thread sealant (pipe dope) on the black pipe joints and reattached the flex with it's compression fitting (no dope here). I turned on the shutoff valve, and using soapy water checked all the connections. No bubbles.
I turned on the water, opened a faucet (blew out the air) and ignited the pilot (that took awhile.. I'd say over a minute before gas hit the igniter). The heater fired up and warmed the 50gal tank in about 1.5 hours.
While it was warming, I sweated on some fittings to make a copper line from the expansion valve to floor drain.
I suppose I will go down to town hall and file for the permit and have it inspected. The cost is like $55.
On Tue, 15 Mar 2005 00:25:25 -0700, nospam snipped-for-privacy@mesanetworks.net wrote:

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Sure. Do you write material for Leno and Letterman too? Don't worry, we don't know where you live.
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