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Zone valves for NPS 2.5 cast iron pipes

pcatasti Member Posts: 1
Would you be willing/able to recommend a zone valve for my hydronic heating system?
My boiler feeds hot water trough NPS 2.5 cast iron pipes to a two-story house with baseboard convector heaters downstairs, and classic cast iron radiators upstairs. A pump helps with water circulation.
There is a significant temperature differential between the two floors, which I can only anticipate will get worse as outside temperatures drop in the ensuing weeks.
I am considering installing zone valves to create a two-zone system, but I have been struggling to find a valve that fits my NPS 2.5 cast iron pipes. Most of the zone valves I found online have a diameter of only up to 1 1/4".
I appreciate any suggestion. Thank you.


  • Ironman
    Ironman Member Posts: 7,221
    2.5" zone valves are available commercially, but they would be extremely expensive.

    A better approach would be to split the piping between two circulators, if it would allow.

    Can you post some good pics of the boiler and the piping so we can see what you've got?

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    EBEBRATT-Ed Member Posts: 14,495
    Is this an old gravity system converted to forced circulation?? The flow rate needs to be checked and then the valves can be sized. Chances are the valves can be 1 or two sizes smaller than the pipe.

    You need a professional to look at this