Keeping the Zone Valve BDR91 open longer for UFH

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • bruce_miranda
    Automated Home Legend
    • Jul 2014
    • 2307

    Keeping the Zone Valve BDR91 open longer for UFH

    I have my UFH configured as a Zone Valve and I use a BDR91 as my actuator. The BDR91 opens a motorised zone valve, which in turn starts the UFH pump.
    I don't have a Boiler Relay because I use OpenTherm. I still have no idea if the System Parameters will affect my BDR91 Zone Valve or that is only meant for the Boiler Relay.
    It would have been better if I could switch off the TPI for this BDR91, but I can't.
    Hence I would like to keep that BDR91 switched ON for as long as possible each time it is switched on by TPI. The reason being, my UFH pump is an adaptive pump and ramps up slowly on power on. So each time the TPI cycle kicks in, it goes through its start up routine.
    Cycle Rate is 3 per hour with a Min On Time of 1 min. What do I set this to, to keep the BDR91 ON for longer?
  • kevinsmart
    Automated Home Ninja
    • Sep 2018
    • 257

    #2
    I used to have a setup like yours but upgraded to an HM80 mixer valve, which is far superior for single zones, eliminating the overshoots I saw with the BDR91. It doesn’t use TPI but learns the appropriate flow temperature setting.

    The system parameter for Cycle Rate does impact BDR91 TPI behaviour but if I recall correctly Min On Time does not.

    With my system I initially had a Cycle Rate of 3. Although this means a longer ON time it also of course results in a longer OFF time too at partial demand. I found a Cycle Rate of 6 to perform better.

    My pump can be set to adaptive but the manufacturer’s recommendation for UFH is constant speed mode.

    Comment

    • bruce_miranda
      Automated Home Legend
      • Jul 2014
      • 2307

      #3
      My UFH uses a GRUNDFOS UPM3 AUTO L and just reading the manual it appears that for almost 5 years I've not realised that my installer has forgotten to change the default setting of the pump from Proportinate Pressure to Constant Pressure! I seem to have 3 options of Constant pressure curves. Any idea how to decide which one I should use?

      Comment

      • bruce_miranda
        Automated Home Legend
        • Jul 2014
        • 2307

        #4
        Also, am I to use Constant Pressure or Constant Speed in an UFH installation?

        Comment

        • kevinsmart
          Automated Home Ninja
          • Sep 2018
          • 257

          #5
          Constant Pressure, probably with the minimum curve setting/speed required to achieve your designed manifold flow rate.

          Comment

          • bruce_miranda
            Automated Home Legend
            • Jul 2014
            • 2307

            #6
            Anyone know where I can buy the HM80. These guys don't seem to want to respond to my enquiries.

            Comment

            • kevinsmart
              Automated Home Ninja
              • Sep 2018
              • 257

              #7
              Originally posted by bruce_miranda View Post
              Anyone know where I can buy the HM80. These guys don't seem to want to respond to my enquiries.
              https://theevohomeshop.co.uk/mixed-c...ontroller.html
              That’s where I got mine but I had to wait a while, as production was moving to a new factory. It was worth it though, but the EvoHome shop don’t have much experience of it, so couldn’t provide much support. I can help you there though.

              There were a few suppliers in Europe where it is more commonly used, but they also appear to be out of stock too.

              It’s actually manufactured in Scotland now, it could be production was put on hold due to Covid, as I heard PPE was being manufactured there.

              Comment

              • kevinsmart
                Automated Home Ninja
                • Sep 2018
                • 257

                #8

                Comment

                • kevinsmart
                  Automated Home Ninja
                  • Sep 2018
                  • 257

                  #9

                  Comment

                  Working...
                  X