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Zone valve size

REKBDR
REKBDR Member Posts: 39
I have a hot water system with two zones. I want to replace both zone valves, but I notice that one is 1” and the other is 3/4”, even though the surrounding copper piping on both is 1”. Is there some reason why one valve is smaller, or any reason not to simply replace both of them with 1” size ?

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 9,630
    Valves should be sized on the expected flow through each zone. Not having that information I would keep the valves the same size as they are now.
  • hot_rod
    hot_rod Member Posts: 14,865
    what brand? Got a pic?

    Most times 3/4 and 1” have about the same flow number.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • REKBDR
    REKBDR Member Posts: 39
    Both are White Rodgers, 3 wire valves. The smaller one is installed in a 1” copper line using reducing couplers on each side of the valve body, Years ago, the copper piping was put in to replace the iron pipe that was original to the house in the 1920s.

    I'm beginning to think that the smaller one was used to save a few bucks on a zone that (originally) needed less flow. Over the years radiators have been taken out and others added, so the balance could way off today.

    I'm inclined to just clean up the arrangement by installing two 1” zone valves and adding a separate valve nearby in each line to reset the balance of the flow. Workable?
  • hot_rod
    hot_rod Member Posts: 14,865
    I suspect you have these "blockhead" WR valves? If so the 1" does have a larger opening. Both both have huge Cv (GPM at 1 psi pressure drop)

    If you like the look of the valve sized to the tube, no harm in using 1" on both.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • REKBDR
    REKBDR Member Posts: 39
    Yup, that's what I’ve got.

    Any recommendation as to what type of valves to install as balancing valves?

    Thanks.

  • hot_rod
    hot_rod Member Posts: 14,865
    This is a user friendly balance valve that we manufacturer. Pull the ring and observe and adjust flow. If it has old iron radiators, it is wise to add a magnetic dirt separator to keep that crud out of all the components, especially the balance valves :)

    Any idea what flow rate you are shooting for? Look for a balance valve with the GPM you plan on using in the mid range of the valve.
    In other words don't oversize the balance valve then choke it way down to get the flow you need.

    https://www.caleffi.com/sites/default/files/file/01149_17_na.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • REKBDR
    REKBDR Member Posts: 39
    Thanks. I appreciate your input.