Adding underfloor heating to existing system

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  • stevelup
    Automated Home Jr Member
    • Mar 2015
    • 35

    #16
    Originally posted by mtmcgavock View Post
    Assuming you've already got existing stats in place (Wired ones) you'd just wire the A and B ports to what would be the existing stat (So it makes and breaks the circuit). But yes the HCC80 would make for a better install.
    My current system is entirely wireless.

    12 x HR92
    2 x BDR91 (one for DHW, one for boiler control)

    Steve

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    • mtmcgavock
      Automated Home Legend
      • Mar 2017
      • 507

      #17
      Originally posted by bruce_miranda View Post
      The Y87RF kits (T87RF + BDR91) can be had for less than 70 a pack. However I am intrigued as to how you can use multiple BDR91s on a single manifold to zone without any actuator heads?
      Well you couldn't, you'd need actuator heads whether you had a HCC80 or BDR91. I don't think anyone stated that you could?

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      • bruce_miranda
        Automated Home Legend
        • Jul 2014
        • 2307

        #18
        how are the actuators powered in a BDR91 installation? I thought the HCC does PWM so allows for pin travel? I would imagine in a BDR91 scenario you get all open or closed.

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        • mtmcgavock
          Automated Home Legend
          • Mar 2017
          • 507

          #19
          Originally posted by stevelup View Post
          Ok, back to the 'integration' question.

          Existing Y-plan system stays exactly as it is
          Manifold added on the flow and return of the heating system (no valve needed?)
          3 (or 4) BDR91s driving the actuators on the manifold. Aux contacts on the actuators driving the UFH pump

          That's it? Will this still trigger the existing BDR91 to activate the boiler?
          No, if you are having UFH you'd have to change you system to an S plan, and have a motorised valve for the UFH. However seeming you have HR92s everywhere all you would need is a 2 port valve on the Hot Water. The heating wouldn't need a 2 port valve (Remember any rads without HR92s would come on with ANY demand) as of your HR92s. I'd put one on the UFH manifold but wire it to the pump. So it opens and closes when the pump runs. You'd need actuators for all the manifold circuits (4), you can get 2 wire and 4 wire actuators. I got 4 wire ones at the time due to not having Evohome, however seeming they only need to open and close I think you'd get away with two wire ones.

          EDIT: Thinking about it, you'd have to have the 4 wire ones. The 4 wire ones include a microswitch to switch the pump and MV open. Just drawn out a quick diagram to think why the reason was I got 4 wire ones!

          Last edited by mtmcgavock; 29 December 2017, 04:37 PM.

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          • mtmcgavock
            Automated Home Legend
            • Mar 2017
            • 507

            #20
            Originally posted by bruce_miranda View Post
            how are the actuators powered in a BDR91 installation? I thought the HCC does PWM so allows for pin travel? I would imagine in a BDR91 scenario you get all open or closed.
            The power would come from the S/L on the BDR91 (So L to A, and B to actuator). At the end of the day all the actuator does is act like a motorised valve.

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            • stevelup
              Automated Home Jr Member
              • Mar 2015
              • 35

              #21
              Originally posted by mtmcgavock View Post
              No, if you are having UFH you'd have to change you system to an S plan, and have a motorised valve for the UFH. However seeming you have HR92s everywhere all you would need is a 2 port valve on the Hot Water. The heating wouldn't need a 2 port valve (Remember any rads without HR92s would come on with ANY demand) as of your HR92s. I'd put one on the UFH manifold but wire it to the pump. So it opens and closes when the pump runs. You'd need actuators for all the manifold circuits (4), you can get 2 wire and 4 wire actuators. I got 4 wire ones at the time due to not having Evohome, however seeming they only need to open and close I think you'd get away with two wire ones.

              EDIT: Thinking about it, you'd have to have the 4 wire ones. The 4 wire ones include a microswitch to switch the pump and MV open. Just drawn out a quick diagram to think why the reason was I got 4 wire ones!

              https://www.colglo.co.uk/product.php?product=UFCHF5100
              Perfect - thanks.

              Comment

              • bruce_miranda
                Automated Home Legend
                • Jul 2014
                • 2307

                #22
                Oh so the actuators don't allow partial closure on UFH manifolds? Like the HR92 on a TRV?

                Comment

                • jdp80
                  Automated Home Jr Member
                  • Mar 2016
                  • 38

                  #23
                  Not AFAIK. The only oddity is that some are Normally Closed and others are Normally Open, but this is obviously something a BDR91 can handle!

                  Comment

                  • Dan_Robinson
                    Automated Home Ninja
                    • Jun 2012
                    • 347

                    #24
                    Originally posted by bruce_miranda View Post
                    Oh so the actuators don't allow partial closure on UFH manifolds? Like the HR92 on a TRV?
                    The PWM would cope with this, but we don't get it here.
                    Kind Regards - Dan Robinson (Jennings Heating Ltd)

                    Comment

                    • bruce_miranda
                      Automated Home Legend
                      • Jul 2014
                      • 2307

                      #25
                      a while ago there was a thread about an electrical alternative to the HR92 as it was considered noisy. Is the electrical alternative the same as used on the UFH manifolds?

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                      • rvb99
                        Automated Home Sr Member
                        • Oct 2017
                        • 74

                        #26
                        We added 2 ufh zones each with 5 and 2 hydraulic circuits respectively in to single manifold with mixing pump. The HCC with a T87RF for each zone works flawlessly and was extremely simple to install. It also makes for a very neat installation.
                        With the HCC you have flexibility in that you can group the hydraulic circuits connected to each manifold port( each with an actuator connected to different HCC "zones”)to different evohome zones.
                        Last edited by rvb99; 31 December 2017, 10:11 AM.

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                        • stevelup
                          Automated Home Jr Member
                          • Mar 2015
                          • 35

                          #27
                          Cheers - missed the notification on this - wasn’t being deliberately rude!

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