I've got a basement full of old half-inch copper pipe, and some of it needs to be replaced. I want to do repairs in 3/4" pipe but I'm wondering if that will cause problems with the water changing pipe sizes on its way to an outlet. Can I do this?
Maybe. When I need to feed two appliances, I use 3/4", otherwise it is 1/2".
It will cause a problem if there are long runs on the Hot side.
3/4" pipe has roughly 50% more area than 1/2", meaning that 50% more volume of water has to be drawn from a distant faucet before Hot water arrives. That may be trivial or it may be a real pain in the neck.
How do you know it 'needs' replacement? Looks tarnished?
OP- Speedy Jim is on the right track about 3/4" vs 1/2" (both nominal size copper tube) but unless my calcs are wrong...the 3/4" tube will have closer to twice as much cold water volume to clear. This will double your hot water wait time.
Why does the copper need replacing? acidic water? leaks?
I dont see why varying pipe size would otherwise cause problems.
cheers Bob
There is white crud coming out of some of the copper joints. What is that? I expected green corosion instead. Should I replace all those joints?
But my primary leak right now is where a water pipe has been touching the conduit for the main house power for fifty years or so, and the contact has caused a pinhole leak, of 5 or 6 gallons a day. I'm looking at inserting a "universal pipe repair clamp" between the pipe and the conduit, before I think about replacing sections of pipe.
Thanks both of you. I'll have to look at how long the hot water runs are.
No, it has approximately 125% more area. The exact difference depends on whether you're talking about type K, L, or M pipe.
One of the women at my church complains there is "never any hot water". I timed it one night, something like 4 1/2 minutes for the hot water to arrive. I'm wondering if they used 3/4 copper. I think they have water saver aerators, which I ought to drill out.
Sounds like a good idea, to replace the white edged joints. Use solder made for drinking water.
As to the pinhole. If it's what I think the patch thing (rubber and a clamp) will also separate the pipe from the girder, so it doesn't continue to wear.
It's not a bad idea to take 3/4 to the last "T" in the system , then take the last two branchs on in 1/2" . BUT do keep in mind, that on the hot side, you'll be slowing down the hot getting to the fixture.
Christopher, you may want to check into putting one of these in at the farthest away point.
The white crud may just be surface corrosion. Clean it off, put a coating like petroleum jelly on it and see if it comes right back. Or it may be minerals from the water if in fact there is a tiny leak. If a leak, it will start in one spot and spread, If corrosion, it usually goes around the exposed solder.
As for the pin hole, fix it properly by cutting out a section and sweating in a new one. Then be sure it does not contact the hanger again. Any sort of rubber will do the job.
It would take a lot more than standard pipe insulation to prevent "the wait for hot water" problem you are responding to.
Foam pipe insulation will only cut the hot water wait time by an insignificant fraction of the current wait time.
Wait time is driven by hot water flow rate to the fixture and volume of cold water sitting in the hot water piping to the fixture. Volume of cold water in the hot water piping to the fixture is determined by run length & pipe size.
Typical hot water pipe insulation will reduce heat loss while the water is being delivered but it wont keep it hot forever (overnight)
cheers Bob
Respectfully suggest that the reason for the pipe leak at the point of abrasion with the conduit is and could be due to two factors. (Possibly three!).
1) There is slight movement between the two. Possibly aggravated by copper pipe expansion/contraction with temp of water, also vibration? 2) The conduit and pipe are two different metals. With the least of moisture and/or condensation over a long period of time, a small point of electrolytic corrosion between the two metals may have occurred? 3) There is remote possibility of very, very small voltages on the grounded? conduit, which possibly could also lead to electrolytic corrosion. In our house the water and electrical grounds and the incoming conduit are not close together; however we have bonded the cold water pipe to the main ground with a #2 AWG wire and marked it with green tape. It is also bonded to another ground which happens to be a loop of #6 AWG buried in the ground long ago when the house was being built.Separate the pipe and the conduit. But suggest that id f this only problem after 50 years do not start wholesale replacement of half inch copper pipe. However if you ARE doing some renovations; e.g bathroom then install new copper in that area only as you do the renovation. We have all half inch water plumbing, installed by myself nearly 40 years ago. Fairly acidic water, but no leaks.And when we renovated bathroom some years ago did replace inaccessible copper, for that area only, at that time. We initially used a well/septic system. But have had municipal water for some 30 years; no problems with either. If you do any replacements recommend use 'ball valves' and section each part of the house system. They are more reliable since do not use washers and turn on/off with a quarter turn!Bert Byfield wrote: ...
All you need is a slip over coupling (one w/o the ridge in the middle) expressly for the purpose.
Cut the pipe at the location of the pinhole, clean the ends (remember to also ream the inside of the cut to get rid of burs), then slip the fitting over, flux and solder. Done.
Then, as somebody else noted, fix the contact point so the two don't touch in some fashion and it'll probably outlast you.
I'd not worry about the rest until actually had a demonstrable problem. Like the above, unless you have something very corrosive in the water or other problems, likely it will no longer be your problem when it actually requires replacement.
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I had never before understood why some of the couplings had ridges and some did not. But also this pipe is only half an inch from the ceiling so I can't get a regular pipe cutter to roll around it, and would have to use that saw like a hacksaw blade with a handle at only one end. I've had trouble doing this before, because the soft copper bends a bit and is then hard to fit to the coupling. Is there a better way to cut this pipe, or do I just have to go slowly and ream out the result?
Most of the couplings I see just have a little dimple that keeps the pipe from sliding through. Needing a repair coupling I have just hammered the little dimple out. This usually saves me a trip and I dont have some salesperson asking me what the heck am I talking about.
Jimmie
You might have to call the public services department in your town, and get 3/4 inch water instead.
More seriously, it will make little difference, except.... if there is a long run of pipe, or lots of elbows and shut offs, the 3/4 has lower resistance to flow. And it will take longer for the hot water to arrive.
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