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.

mixing valve ?

bill_8
bill_8 Member Posts: 15
in THE MAIN WALL
on a floor radiant system with many zones do you like to use a mixing valve on each zone?

Comments

  • Alan(OnVacationInOregon)Forbes
    Alan(OnVacationInOregon)Forbes Member Posts: 232
    No Way

    I don't like anything that's going to cost me more money. If you've got a bunch of zones, use only one mixing valve UNLESS (and that's a big unless) there are different floor "sandwiches". If you have a few zones that are slab-on-grade, you don't want them on the same mixing valve as zones that are staple-up or on the same mixing valve as zones that are in a thin slab, etc.

    If these are mixing valves that are driven by outdoor reset systems, they will have different reset ratios and different temperature starting points.

    This probably holds true for injection mixing as well.

    Alan
  • hr
    hr Member Posts: 6,106
    depends on

    thge supply temperature requirements. Any more than a 15 degree spread, I go with additional mixers. Watch the Cv rating on mix valves also.

    hot rod

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
  • bill_8
    bill_8 Member Posts: 15


    my supply temp is 120 degrees. 7 zones are suspended tube with AL track of which 1 of those is U/S. 1 zone is in basement and will be a sleeper system on concrete and the ninth zone is in slab in the garage. I've seen schematics where each zone has a manual mixing valve then there is a master motorized mixing with outdoor reset that serves the zone manifold. Your point about saving money is well taken....you can really go wild with some of this stuff. Several of my zones vary quite a bit from other zones from heat load to number of loops so want to make sure system works well.
  • bill_8
    bill_8 Member Posts: 15
    when you say

    additional mixers do you mean one on each zone? As I said to CA radiant I have several zones that vary quite a bit in terms of heat load and number of loops. Somes zones don't need as high a temp as others which is why I was considering a manual mixing valve on each zone and then a motorized valve with outdoor reset at the zone maniflold. When you say 15 degree spread do you mean from zone to zone? My supply temp will be 120 degree with 9 zones...7 with plates (1 upstairs), 1 concrete garage in slab, and 1 basement sleeper system on top of slab.

  • hr
    hr Member Posts: 6,106
    You've got it

    If I have a slab that requires 100 degree and say some plate application requiring 130 degrees you would want to consider two different temperature mixing stations. Maybe!

    If you had a condensing boiler you could run it at 130 degrees and just mix down one temperature.

    If you have a regular cast boiler that needs to run 160 degree, you may need a couple mix stations.

    Generally mix valve spec sheets will tell you the GPM or Cv number. This will tell you how large of a zone that valve could supply.

    The popular Honeywell/ Sparco has a Cv of 3.1 for 3/4" and 3.2 for the 1". Figure a 30,000 BTU/ hr load safely with these valves. Just depends on the components you chose and the load they have to supply.

    There isn't just one right answer to your question. A good heat loss and system design should give you the info you need to select the temperature and flow requires to the various zones.

    hot rod

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
This discussion has been closed.

Categories