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Check Valve Woes

SwisherSwisher Member Posts: 15
Hello Everyone!

I need the benefit of experience. Here's the problem:

1. Installed iron rads in two different zones with common return line. Found that return flow from one zone was back-flowing through rads in neighbouring zone, delivering heat there even when thermostat called for none.

2. Installed swing check valve in floor frame where rad pipes travel, found the check valves sometimes made noise. Also reconsidered the wisdom of installing check valve in floor frame that would be sealed under new hardwood floor later on.

3. Removed swing check valves and installed spring check valve in pipe leading down from rad into the floor. Idea being ease of future replacement and quiet operation.

4. Check valves only installed in two of the four rads in the affected system, now all water flows to the two rads with no spring check valves, unless those rads are shut off manually. And even when these valves are shut, flow through rads with spring checks doesn't always happen. It seems the springs are too strong. There's definitely no air in the lines to block flow.

Is there any value in me pulling the rads off again, removing the springs from the check valves, then buttoning everything up again? The spring checks are in a vertical position, so gravity and any attempt at back flow should close the valves when they need to be closed.

Am I on the right track? Will the check valves make rattling noises without their springs?

In hindsight, I should never have installed a common return line for two zones, but I can't change that now.

Thanks a million!




  • EricEric Member Posts: 261
    edited February 2013
    A swing check.

    A swing check does not belong on a heating system. So remove or eliminate them.

    You can only use a flo check (or) sweat check valve if the zones each have their own pump. If they share a pump you have to use a zone valve on each zone.

    Check valves won't work with one pump for all.

    Also.... mechanical things like pumps and checks and zone valves should be installed near the boiler in the boiler room,  not half way across the house. You may want to take some pictures of the tees that split the zones off on the supply end, and where they join on the return end. You will help us out with what your talking about.
  • Jamie HallJamie Hall Member Posts: 6,694
    Nothing wrong

    with spring checks, but they should open on only a few psi of head.  And you must have them on all the radiators -- otherwise the water, being lazy, will take the route without them.

    And even though they should open on only a few psi, if there is another way for the water to circulate somewhere in your system, believe me -- it well.  That may be why they don't open sometimes.

    I wouldn't operate them without the springs, though -- they may not close properly, or may rattle.

    Just make sure the system has more or less even pressure drops around all the available loops.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • SwisherSwisher Member Posts: 15
    Thanks for your help

    Thanks for your prompt help.

    My less-than-ideal plan for using a common return line for two zones makes it necessary to install these check valves away from the boiler room, and I decided to go ahead and remove the springs. It actually didn't take that long and water flow seems even and quiet now. So far, this looks like success.

    Thanks again,

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