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  1. #1
    Join Date
    Mar 2008
    Location
    Houston
    Posts
    16

    Default galvanized to copper pipe size

    I am remodeling my kitchen and need to move hot and cold water pipes. I currently have 1/2 inch galvenized pipes. I want to replace with copper and accidentally bought 3/4 inch copper. What would the ramifications be if I tie into the 1/2 inch galvenized with the 3/4 inch copper? Would I have more pressure or less pressure in my sink and dishwasher? Thanks.

  2. #2
    Join Date
    Feb 2008
    Location
    Nashville, TN
    Posts
    149

    Default Re: galvanized to copper pipe size

    Since it is a tie-in and not a new service it will be increased volume(amount) of water. and it will be decreased preasure of water.

    Think of the galvanized pipe as a constrictor which will delivery less water at a higher pressure. Part of the reason galvanized is alo bad is the corrosion on the inside of the pipe. Look inside what you have taken out. Is there any rust or build up of minerals? Now you are adding a larger pipe that will still only b supplied by a 1/2" line. I don't think the drop in pressure will be signifigant, but it may still be a change in the pressure. Good luck. Process of elimination.

  3. #3
    Join Date
    Mar 2008
    Location
    Houston
    Posts
    16

    Default Re: galvanized to copper pipe size

    There is some build up but it is a small amount surprisingly after about 35 years. It sounds like going to 3/4 would be a large drop in pressure.

  4. #4
    Join Date
    Feb 2008
    Location
    Pasadena, Calif.
    Posts
    24

    Default Re: galvanized to copper pipe size

    I have done the change too. Everything he says is right. You are going to loose pressure. I like to add to that: Don't forget to put a dialectric union between the galvanized and the copper pipe.

  5. #5
    Join Date
    Mar 2008
    Location
    Houston
    Posts
    16

    Default Re: galvanized to copper pipe size

    Yes, thanks. I already looked at the dielectric unions and only found 3/4 inch. Do they make them in 1/2inch?

  6. #6
    Join Date
    Feb 2008
    Location
    Nashville, TN
    Posts
    149

    Default Re: galvanized to copper pipe size

    good call Gabriel. As far as the reducing just solder up a little transition piece with a 1/2" Mip to 3/4" copper coupling. That way you can use the 1/2" dialectric union. The same can be by putting a 1/2" to 3/4" bell reducer on the gali and going up to a 3/4" dial. union. 6 to one, half a dozen to another. Good luck. Process of elimination.

  7. #7
    Join Date
    Mar 2008
    Location
    Houston
    Posts
    16

    Default Re: galvanized to copper pipe size

    thanks to everyone for your useful advice.

  8. #8
    Join Date
    Jul 2008
    Location
    San Francisco , Ca
    Posts
    43

    Default Re: galvanized to copper pipe size

    Quote Originally Posted by doingitall View Post
    thanks to everyone for your useful advice.
    note dielectric unions can only be used is accessible locations. i generally dont use dielectric unions because the new versions rely on a rubber seal at the union instead on the old ones wich had a ground joint connection/ in walls and unaccessible locations to transition from galvy to copper tube i recomend a 6" brass nipple with a copper female adapter threaded on

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