Galvanized to copper

[Pasgnetti]

[?]I'm knew with plumbing, I'm remodeling a bathroom and want to change the old galvanized pipes with copper. I have started using 1/2" copper pipes, but I'd like anyone to tell me if there's anyway to determine how to replace them. Say, if the pipes are 5/8 galvanized, can I go to 1/2" copper? or is there any table that might tell from one size to the other on different materials?[?]

[reader4]

I would like to revisit this thread... I have a similar question and was wondering where to find more info. We are redoing a kitchen and I might like to replace the feedlines with copper. Eventually we may want to do the whole house.

Currently, the house is fed by a 3/4" CU main, but everything after that is 5/8" (I think... ~7/8" OD) galvanized pipe. There is one kitchen sink, two bathroom sinks, one shower and two toilets plus the utility sink and washer - all within about 15-20ft of the main supply. We plan to add a dishwasher.

Any advice or clues about good reading material?

[HayZee518]

usually supply lines are 3/4 copper off the cold and hot water supplies. when you approach the appliance the 3/4 is reduced to 1/2 inch copper AND 3/8" supply tubes on the fixtures - toilet, kitchen faucet, bathroom lavatory sinks etc. if you branch off a 1/2 inch line to a sink, there's no real volume of water so a pressure drop is negligible. heavy users like a shower may suffer however. In my house I have 3/4 inch running the length of the house both for cold and hot. where I tapped in I used 1/2 inch copper through a reducing TEE to feed whatever fixture I had. that way the volume of water was there at all times. I can run the dishwasher during fill and the sink hot water at the same time without any appreciable drop in pressure.

[reader4]

This is exactly what I was planning. My concern is that it will have to be done in stages... part now, part later. The upstairs bath is fed from 1/2" lines running off the 5/8" galvanized and the pressure is terrible. I didn't want to go through all the hassle of installing copper for the kitchen and then have the same problem. Any ideas why the pressure might be so bad upstairs? It is pretty good other places in the house.

[HayZee518]

Galvanized steel pipe stinks for water supply lines. Chlorinated water, flouridated water plus the basic minerals in the water tend to build up deposits withing the pipe's walls - something like the plaque the medical folks say about arteries. Eventually the wall of the galvanized pipe will close up completely. Copper piping forms its own oxide coating inside and outside but it isn't affected by the minerals. If you mix galvanized and copper you need a dielectric union between the two. Galvanized steel is an electro-deposited coating of zinc. Without the dielectric union, right at the joint, you have a battery. And this "battery" generates a small voltage and starts to leach out minerals in the galvanized pipe which eats away at the joint. Eventually the pipe fails - water - water everywhere! For soldering copper joints use a lead free flux and a lead free solder.

[LazyPup]

There is no 5/8 galvanized iron pipe!

You are mistakenly measuring the outside diameter while all "Pipe" is specified by inside diameter.

Galvanized iron pipe used in the potable water distribution system for residential applications are 1/2", 3/4" 1" and in rare circumstances 1-1/4". 1-1/2" & 2".

When replacing galvanized iron pipe with copper pipe you must use the same size of pipe or the entire potable water distribution system would need to be recalculated for load.

Also, you must use a dielectric union, dielectric nipple or a 6" hardened bronze nipple to make a transition from galvanized iron to copper pipe.