UFH - EvoHome and reluctant plumber

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  • kevinsmart
    Automated Home Ninja
    • Sep 2018
    • 257

    #46
    Originally posted by bruce_miranda View Post
    Where do you see a 3 way in my set up?
    I’m assuming that’s a flow connection at the bottom, return at the right of the thermostatic valve and supply at the top. So you would junk your thermostatic valve for a 3-port: one port flow, one port return, one port supply to manifold.

    Comment

    • bruce_miranda
      Automated Home Legend
      • Jul 2014
      • 2307

      #47
      It's actually a flow and return at the bottom from/to boiler. Then to the Top is the mixed manifold flow going into the pump, and then coming from the Right is the manifold return.
      Hence my question. Why would my UFH pump dead end if I simply shut off the boiler flow. Wouldn't the UFH just continue to circulate the water through the manifold loops, but with no new hot water coming in from the boiler flow.

      Comment

      • kevinsmart
        Automated Home Ninja
        • Sep 2018
        • 257

        #48
        Originally posted by bruce_miranda View Post
        It's actually a flow and return at the bottom from/to boiler. Then to the Top is the mixed manifold flow going into the pump, and then coming from the Right is the manifold return.
        Hence my question. Why would my UFH pump dead end if I simply shut off the boiler flow. Wouldn't the UFH just continue to circulate the water through the manifold loops, but with no new hot water coming in from the boiler flow.
        It wouldn’t with your current setup but certainly in my case the motivation was to replace a thermostatic mixing valve/blender with an actuator controlled rotary valve. Is that not what you want to do?

        Comment

        • bruce_miranda
          Automated Home Legend
          • Jul 2014
          • 2307

          #49
          Yes and No. I actually want the UFH pump to stop doing TPI because I do not believe it should. I am also thinking that if I can control the temperature of the water coming into the manifold TRV, then I am effectively doing away with the TRV in any case, because it would be open completely.

          Comment

          • bruce_miranda
            Automated Home Legend
            • Jul 2014
            • 2307

            #50
            Kevin, I looked at your previous configuration picture again. In your case too, if you shut off the flow from the boiler completely, wouldn't your UFH pump just circulate the water round the manifold loops, especially since I note you don't the powered actuator heads arent used on the manifold returns, so they will must be fully open.

            Comment

            • kevinsmart
              Automated Home Ninja
              • Sep 2018
              • 257

              #51
              Originally posted by bruce_miranda View Post
              Kevin, I looked at your previous configuration picture again. In your case too, if you shut off the flow from the boiler completely, wouldn't your UFH pump just circulate the water round the manifold loops, especially since I note you don't the powered actuator heads arent used on the manifold returns, so they will must be fully open.
              Yes, that’s correct and what we want to achieve. My point is if you could find a 2-port rotary/modulating valve, rather than 3/4-way, and were to replace your TMV you would face this issue and need an auto-bypass valve.

              Alternatively you could use this valve to supply your current setup.

              But, so far I can’t find a suitable 2-way for the HM80.

              So back to either using a 3-way or 4-way rotary valve and restrict flow. No need for an auto-bypass in this case.

              If you just want to eliminate TPI you could use the HM80 to control your pump and zone valve, but it would of course have no control over the flow and you might see overshoots. Maybe less of a problem with OpenTherm but it depends on what your other zones are demanding.

              Comment

              • kevinsmart
                Automated Home Ninja
                • Sep 2018
                • 257

                #52
                Originally posted by kevinsmart View Post
                Yes, that’s correct and what we want to achieve. My point is if you could find a 2-port rotary/modulating valve, rather than 3/4-way, and were to replace your TMV you would face this issue and need an auto-bypass valve.

                Alternatively you could use this valve to supply your current setup.

                But, so far I can’t find a suitable 2-way for the HM80.

                So back to either using a 3-way or 4-way rotary valve and restrict flow. No need for an auto-bypass in this case.

                If you just want to eliminate TPI you could use the HM80 to control your pump and zone valve, but it would of course have no control over the flow and you might see overshoots. Maybe less of a problem with OpenTherm but it depends on what your other zones are demanding.
                Maybe these?!



                Comment

                • bruce_miranda
                  Automated Home Legend
                  • Jul 2014
                  • 2307

                  #53
                  What might happen if I just used the ON output of the HM80 on a normal 2 port zone valve and have the flow sensor attached to the output pipe of the 2 port zone valve?

                  Comment

                  • kevinsmart
                    Automated Home Ninja
                    • Sep 2018
                    • 257

                    #54
                    Originally posted by bruce_miranda View Post
                    What might happen if I just used the ON output of the HM80 on a normal 2 port zone valve and have the flow sensor attached to the output pipe of the 2 port zone valve?
                    I don’t think there would be any point connecting the flow sensor as the HM80 won’t be able to correlate its (unconnected) rotary position to it. The HM80 can also operate without the flow sensor where it will, using fuzzy logic, try to correlate the difference from set point to a rotary valve position.

                    Bear in mind though that the HM80’s goal is to balance the heat loss, so the pump will continue to run even when there is only a 1% zone demand. So I suspect your zone would overshoot compared with your current BDR91 TPI setup.

                    You could maybe replace your zone valve with the 2-port rotary actuator I found above. The actuator wiring appears to be compatible: Neutral, Clockwise, Counter-Clockwise.

                    Comment

                    • bruce_miranda
                      Automated Home Legend
                      • Jul 2014
                      • 2307

                      #55
                      How about something like this
                      Plumbing Superstore is one of the UK's leading online plumbing suppliers, offering John Guest Speedfit, Armacell, Pegler Yorkshire and more.


                      Also how does one go from the DN20 or 3/4th inch threads to 22mm copper pipes?

                      Comment

                      • kevinsmart
                        Automated Home Ninja
                        • Sep 2018
                        • 257

                        #56
                        Originally posted by bruce_miranda View Post
                        How about something like this
                        Plumbing Superstore is one of the UK's leading online plumbing suppliers, offering John Guest Speedfit, Armacell, Pegler Yorkshire and more.


                        Also how does one go from the DN20 or 3/4th inch threads to 22mm copper pipes?
                        That looks as if it might do the trick. I guess you will need some compression adapter couplers.

                        Comment

                        • bruce_miranda
                          Automated Home Legend
                          • Jul 2014
                          • 2307

                          #57
                          How did you go from the V5442 to 22mm pipe? The reason I looked at the valve I linked to earlier was because like the V5442 it is DN20 internally threaded. Whereas the VBG2 that you had linked to, seems to be externally threaded which might mean I need to find some adapters.
                          Maybe something like this should work, I guess?
                          Last edited by bruce_miranda; 2 January 2021, 12:35 PM.

                          Comment

                          • kevinsmart
                            Automated Home Ninja
                            • Sep 2018
                            • 257

                            #58
                            Originally posted by bruce_miranda View Post
                            How did you go from the V5442 to 22mm pipe? The reason I looked at the valve I linked to earlier was because like the V5442 it is DN20 internally threaded. Whereas the VBG2 that you had linked to, seems to be externally threaded which might mean I need to find some adapters.
                            Maybe something like this should work, I guess?
                            https://www.screwfix.com/p/compressi...ails_container
                            My heating engineer handled all of that.

                            Probably something like this:


                            And some soldered elbows/couplers.

                            Comment

                            • bruce_miranda
                              Automated Home Legend
                              • Jul 2014
                              • 2307

                              #59
                              I finally managed to find a brand new HM80 and the associated 20K NTC flow sensor for sale.
                              I have no idea what the new solution for a mixer valve control is meant to be if HM80 is now considered obsolete.
                              I have also bought the 2 port rotary valve. The bought the 3/4th inch (DN20) version because that is the closest to the 22mm copper pipe I have feeding the UFH manifold.
                              I need to buy two compression irons to go from the valve back to the 22mm copper pipe.
                              Plumbing Superstore is one of the UK's leading online plumbing suppliers, offering John Guest Speedfit, Armacell, Pegler Yorkshire and more.

                              Plumbing Superstore is one of the UK's leading online plumbing suppliers, offering John Guest Speedfit, Armacell, Pegler Yorkshire and more.


                              The idea is to replace the currently installed NC 2 port motorised zone valve feeding the manifold. I will set the flow temperature required on the HM80 to just a little over what the TRV on the manifold is set to.
                              This should mean the TRV on the manifold stays almost fully open, as opposed to what it must currently be almost fully closed. So rather than 65C hot water reaching the manifold, the manifold will (in theory) be fed with 35C hot water.
                              With the HM80 also handling the pump, this should remove the TPI that cannot be removed when using a
                              BDR91.

                              Will let people know how I get on, when I can find a plumber to fit this for me. I certainly won't be touching the heating system in the winter and definitely this doesn't class as essential during lockdown.

                              Comment

                              • kevinsmart
                                Automated Home Ninja
                                • Sep 2018
                                • 257

                                #60
                                Originally posted by bruce_miranda View Post
                                I finally managed to find a brand new HM80 and the associated 20K NTC flow sensor for sale.
                                I have no idea what the new solution for a mixer valve control is meant to be if HM80 is now considered obsolete.
                                I have also bought the 2 port rotary valve. The bought the 3/4th inch (DN20) version because that is the closest to the 22mm copper pipe I have feeding the UFH manifold.
                                I need to buy two compression irons to go from the valve back to the 22mm copper pipe.
                                Plumbing Superstore is one of the UK's leading online plumbing suppliers, offering John Guest Speedfit, Armacell, Pegler Yorkshire and more.

                                Plumbing Superstore is one of the UK's leading online plumbing suppliers, offering John Guest Speedfit, Armacell, Pegler Yorkshire and more.


                                The idea is to replace the currently installed NC 2 port motorised zone valve feeding the manifold. I will set the flow temperature required on the HM80 to just a little over what the TRV on the manifold is set to.
                                This should mean the TRV on the manifold stays almost fully open, as opposed to what it must currently be almost fully closed. So rather than 65C hot water reaching the manifold, the manifold will (in theory) be fed with 35C hot water.
                                With the HM80 also handling the pump, this should remove the TPI that cannot be removed when using a
                                BDR91.

                                Will let people know how I get on, when I can find a plumber to fit this for me. I certainly won't be touching the heating system in the winter and definitely this doesn't class as essential during lockdown.
                                Good stuff, look forward to hearing how you get on.

                                The manifold will of course be fed with water between the HM80 min and max set temperatures.

                                Comment

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