Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Zoning controls: Point me in the right direction (please)

TAG Member Posts: 755
edited November 2019 in THE MAIN WALL
Being an old house guy, I'm never building new -- all of my systems have been a combination of retrofitting an old building and some new -- new being an addition or gutting part of the old building. My method has been Buderus cast Iron boilers w/ Buderus ODR controls. Continuous Circulation. I set them up with the main heating curve pumping out to radiators (old cast or new panel) ... the secondary curve on the boiler running a mixing valve and pump to the radiant floors. All have had some odd space where I was unsure of ... so I set up another pump/ manual bypass ( to be safe) and manifold. Example: one place has a green house with brick floor off the kitchen. Another a large tiled room w/ lots of glass. So I have 3 pumps running all the time .... or most of the time (the greenhouse has a floor thermostat controlling the pump). No room thermostats ... some of the individual radiators have temp control.

My new build will be using a Viessmann 200 -- this needs a dedicated boiler pump. Using my above system -- I'm going to be having 4 pumps (at least) running all the time! Is there another way??

The new build has a new lower level slab area of about 700sf w/ loops of 1/2 PEX and an upper 1100sf living room room of retrofitted plates/ 3/8PEX. (not yet installed). So each of those spaces will have a dedicated manifold -- can I use one pump feeding two manifolds ?

The bulk of the house will be Warmboard (two manifolds) -- that will be the main ODR on the boiler. I want individual controls on some of those loops on both manifolds because the Warmboard is room by room dedicated loops. I want to be able to lower the temps in unused bedroom areas.

I have never seen a mixing valve with a pump .. pumping towards the valve. I'm assuming that whenever you need a bypass or temp valve -- you have to have a dedicated pump after the valve .... pumping away.

But -- with only a bunch of manifolds. Can you use one pump ..?


  • SuperJ
    SuperJ Member Posts: 609
    edited November 2019
    You should be able to combine common temperature loads onto a single pump assuming it has the proper capacity even with remote manifolds.
    Look at total flow rate of all the circuits and only the highest fthd requirement return to size your pump. (don't forget to include the manifold supply and return at full flow)
    -If you want to set some rooms back I would suggest putting zone valve in, and using a infloor friendly thermostats that will give better idle characteristics when close to setpoint. (at least for the high mass slab zones).
    Use a delta P pump so it will react to the zone valves opening and closing.

    So I count 3 pumps: boiler pump, slab pump, and warmboard pump. Use ECM pumps everywhere for energy savings. The long hours on pumps make even relatively small wattages add up over the months and years.
  • TAG
    TAG Member Posts: 755
    I see that Viessmann has the Grundfos 15/58 3 speed as a recommended boiler pump .... I don't think that's an ECM.

    I think the alpha is what you speak.?

    It seems more logical to have one pump and two zone valves -- one to the plate setup and another to the slab ..and control the zone valves with floor thermostats.