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Any Issue with mixing of stainless-copper-brass and back again??

JUGHNE Member Posts: 11,021
edited April 2017 in THE MAIN WALL
Might have a pair of HTP Phoenix WH's to install in the future. The supply and return lines are 2 1/2" copper with steel flanges for start points. Hope to leave the flanges in place and go with 2" copper and then SS fittings & nipples to brass ball valves and check valves. Would use SS unions also. Other than looking like odds and ends of fitting materials of SS, brass and copper, does anyone know of a future problem. Also how about leaving the steel/iron flanges in place connected with copper?

The HTP's have SS nipples on SS tank. Also "caution to use no die-unions or galv steel.....use only copper or brass".......one would think that a SS 90 and nipples could be connected to it??

Looking at Merit brand SS that is less than 1/2 price of LF brass.


  • hot_rod
    hot_rod Member Posts: 21,868
    The galvanic series shows various metals, and the closer together on the chart the less potential for galvanic corrosion

    The biggest factor is the fluid, the more conductive the water the greater potential for reaction. Filtered water like DI or RO strips most all the minerals and salts and the water has almost no conductivity. Salt water would be an example of high conductivity and greater galvanic corrosion potential

    It's never a bad idea to check the water with a TDS meter and get an idea of conductivity. If it is high from a lot of minerals in the water you are at a greater risk.

    Im assuming with iron flanges it is a closed loop, not DHW piping? If you fill with good water you should not have issues.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JUGHNE Member Posts: 11,021
    All copper pipe, just some iron flanges with copper MA screwed in.
    Have to reduce from 2 1/2" to 2", might try to change both halves to SS.
    This is for DHW. Replacing a 365 gallon storage tank dated 1975. It has steam heat exchanger coil inserted. 80 HP steam boiler 24/7/365 for 42 years. DHW load is fraction of original. Boiler room temp approaches delivered water temp of 120 in summer.
    Water softener in place for WH tanks.

    I see they feed you better in Iowa. :)
  • Henry
    Henry Member Posts: 996
    Steel flanges are a no-no on DHW. Get rid of them. We install a number of Phoenix hwt. You replace the flanges with copper unions and continue with copper pipe. There is o reason to use SS! BTW we had a great time with Gary and Cory of HTP this week in Montreal for the Mecanexpo. Ask them about our authentic food experiences!
    JUGHNE Member Posts: 11,021
    Henry, upon further investigation the iron flange is CTS/insert on the copper side and plain steel/iron IPS on the other. These appear to be die electric flanges. I realize I don't want/need the die electric feature but would like the flanges for the union feature. Also want to reduce from 2 1/2" copper to 2" and another to 1 1/2".

    Yes simple reducing couplings would work but, I suspect my 40 year old gate valves will not give 100% shut off and soldering on wet pipe is an issue. I suppose a loaf of white bread may be sacrificed for the 2 1/2" transition. I will have a water stopper tool for 2" on down.
    Need to be ready at change over time with all necessary fittings on hand. Rural area 220 miles from any major city. ;)