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Valves or Circs?

Rich Davis_2
Rich Davis_2 Member Posts: 101
What is the guide to determine what to use on the secondary piping? Will be using a mod/con with P/S piping. Do I use valves or circ pumps. Also can I put a small panel radiator in the primary loop with a by-pass valve to allow full flow in that loop. This radiator will be located in a small bathroom about 2' above the boiler. Thanks for the help.
Rich Davis


  • Timco
    Timco Member Posts: 3,039

    How would you control the small panel rad? (TRV?) Pri loop will be pretty hot. I like circs because if one goes down, still heat in rest of house. If one circ, and it fails, no heat period. Also, I have fixed 10 times more ZVs than circs. Also, no need for diff bypass valve and such, but usually costs less than circs depending on how many zones...

    Just a guy running some pipes.
  • Brad White_202
    Brad White_202 Member Posts: 105
    By definition and unless

    you are using a 4-way mixing valve, you will need at least one circulator on the radiation circuit. A proper P/S setup will not allow one circuit (the boiler in your case) to influence flow in the other (the radiation side in your case).

    Personally, I think as a nation we are way over-pumped; those zone circulators add up at 50-60 Watts on low speed...

    For best and most effective distribution, an ECM circulator such as Wilo or Grundfos responding to delta-P and with zone valves downstream would be ideal. Second choice, use TRV's on all radiators.

    With P/S, there is nothing to prevent you from using that circulator, properly sized of course, to impart flow to a parallel zone/radiator. Just allow that the flow will vary depending on how the secondary/radiation circuit is calling. That radiator should have it's own control valve or TRV at least.

    My $0.02

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