Valves or Circs?

Rich Davis_2

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

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...

Tim

Brad White_202

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

Brad