All radiators either on or off

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  • Dan_Robinson
    Automated Home Ninja
    • Jun 2012
    • 347

    #61
    There are connected installers; and there are connected specialists.

    They are clearly separated on the find an installer Web page.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

    Comment

    • willdonal
      Automated Home Sr Member
      • Oct 2017
      • 58

      #62
      Originally posted by DBMandrake View Post
      Normally you would have a safety thermostat built into the cylinder if it is an unvented cylinder, (regs demand it I think) set to cut out at around 65 degrees or so. This would get wired in series with the BDR91 and then go to the hot water zone valve. That way both the Evohome and the safety thermostat can cut the power to the hot water zone valve if the temperature is getting high.

      Yes - whenever the heating was on the hot water temperature would gradually climb towards the flow temperature of the boiler - it sounds like your boilers flow temperature is set very high too for this time of year, perhaps unnecessarily high. I have an old non-condensing system with old radiators that are designed for high flow temps and I still have mine set to only 65 at this time of the year although by the end of October I'll probably have to bump it up to 70.

      Yes that's absolutely fine - generally with Evohome you would have HR92 radiator controllers on all radiators perhaps aside from a towel rail or bypass radiator so the heating zone valves for upstairs and downstairs become redundant because every room is its own zone - in that case you either mechanically latch them open, or my preferred option is to wire them to run off the pump's power supply - that way they always open when the pump runs but they also close when the heating is off to save power and make sure they don't seize from sitting open permanently.

      Another option would be to wire both heating zone valves together to run off your heating BDR91 which would make it a standard S-Plan configuration. The advantage of this is that if you have any radiators without an HR92 like a towel rail, they would not get hot when only hot water is turned on - if the heating zone valves are always open when the system is on you will get some heat to towel rails in summer when only hot water is enabled.

      Some people like that idea, some don't. I have HR92's on all my radiators and also (somewhat redundantly) a heating zone valve as well, so I don't get any radiators heating at all if I only have hot water enabled.

      The hot water zone valve of course does need to be wired to both the hot water BDR91 and the cylinder safety stat if it has one. (If its unvented it will definitely have one, vented may not)

      Still not excusable on their part really - what you have or had sounds like a standard S-Plan+ system with a hot water zone valve and one or more heating zone valves.

      In such a system the hot water zone valve is always what regulates the hot water temperature - previously it was probably controlled with a cylinder stat and a timer, now it is controlled by the hot water BDR91. (And a temperature reading from the Evohome cylinder sensor is sent back to the Evohome controller wirelessly so it knows when to switch that relay on and off)

      Leaving the hot water zone valve wired or held open wouldn't be something you'd ever do on an S-Plan system.
      Thanks for your expertise, this is now way way beyond what I can do myself. the only registered Honeywell installer in my area, still 40 miles away, is very busy. He says he will come end of next week or the week after :-( :-( I will just have to keep an eye on the temperature. Thanks again for your help.

      Comment

      • paulockenden
        Automated Home Legend
        • Apr 2015
        • 1719

        #63
        Another possibility (beyond the horrendous wiring) if your hot water is too hot is that a two port valve (if S plan) has failed and stuck open, so the DHW tank is being heated whenever there's CH flow.

        You should be able to check this by turning one zone on and then feeling the temp of the pipes leading to the heating coil in your tank.

        Comment

        • willdonal
          Automated Home Sr Member
          • Oct 2017
          • 58

          #64
          Originally posted by paulockenden View Post
          Another possibility (beyond the horrendous wiring) if your hot water is too hot is that a two port valve (if S plan) has failed and stuck open, so the DHW tank is being heated whenever there's CH flow.

          You should be able to check this by turning one zone on and then feeling the temp of the pipes leading to the heating coil in your tank.
          The temperature of the hot water is definitely been influenced by the heating coming on. It had dropped to 50 at lunch time but now it is at 67. Time to call in the experts
          :-) :-) Thanks for your input.

          Comment

          • paulockenden
            Automated Home Legend
            • Apr 2015
            • 1719

            #65
            I’d put a small wager on it being a zone valve problem.

            But even though that would eliminate the positioning of the wireless components this time you do need to get that sorted too, else that's just storing up future problems.

            Comment

            • willdonal
              Automated Home Sr Member
              • Oct 2017
              • 58

              #66
              Originally posted by paulockenden View Post
              I’d put a small wager on it being a zone valve problem.

              But even though that would eliminate the positioning of the wireless components this time you do need to get that sorted too, else that's just storing up future problems.
              Thanks, When I explained to the Honeywell Installer he was shocked at how this was all wired up and set up. Unfortunately he cant come for near 2 weeks so for the time being I'm just monitoring it closely. If the water gets too hot I switch everything off. I appreciate your comments :-) :-)

              Comment

              • DBMandrake
                Automated Home Legend
                • Sep 2014
                • 2361

                #67
                In the meantime you could try turning your boiler flow temperature down a bit if your radiators are adequately sized. If your hot water was getting to 77 degrees your boiler flow temperature is probably set to about 80, which is a bit excessive for this time of the year IMHO, especially if its a modern condensing boiler with modern radiators.

                Try turning the flow temp down by 10 degrees - that will knock down the maximum hot water temperature by 10 degrees as well.

                Comment

                • willdonal
                  Automated Home Sr Member
                  • Oct 2017
                  • 58

                  #68
                  Originally posted by DBMandrake View Post
                  In the meantime you could try turning your boiler flow temperature down a bit if your radiators are adequately sized. If your hot water was getting to 77 degrees your boiler flow temperature is probably set to about 80, which is a bit excessive for this time of the year IMHO, especially if its a modern condensing boiler with modern radiators.

                  Try turning the flow temp down by 10 degrees - that will knock down the maximum hot water temperature by 10 degrees as well.
                  Ok will do , Thanks for your input :-) :-)

                  Comment

                  • willdonal
                    Automated Home Sr Member
                    • Oct 2017
                    • 58

                    #69
                    Originally posted by DBMandrake View Post
                    In the meantime you could try turning your boiler flow temperature down a bit if your radiators are adequately sized. If your hot water was getting to 77 degrees your boiler flow temperature is probably set to about 80, which is a bit excessive for this time of the year IMHO, especially if its a modern condensing boiler with modern radiators.

                    Try turning the flow temp down by 10 degrees - that will knock down the maximum hot water temperature by 10 degrees as well.
                    There is a brass screw with numbers beside it and another dial with no numbers. Which one do I adjust?
                    20171004_194333.jpg20171004_194328.jpg

                    Comment

                    • willdonal
                      Automated Home Sr Member
                      • Oct 2017
                      • 58

                      #70
                      Originally posted by DBMandrake View Post
                      In the meantime you could try turning your boiler flow temperature down a bit if your radiators are adequately sized. If your hot water was getting to 77 degrees your boiler flow temperature is probably set to about 80, which is a bit excessive for this time of the year IMHO, especially if its a modern condensing boiler with modern radiators.

                      Try turning the flow temp down by 10 degrees - that will knock down the maximum hot water temperature by 10 degrees as well.
                      The last reply the pictures didn't work for some reason so i'll try again here 20171004_194328.jpg20171004_194333.jpg

                      Comment

                      • DBMandrake
                        Automated Home Legend
                        • Sep 2014
                        • 2361

                        #71
                        Originally posted by willdonal View Post
                        The last reply the pictures didn't work for some reason so i'll try again here [ATTACH=CONFIG]1093[/ATTACH][ATTACH=CONFIG]1094[/ATTACH]
                        That's your hot water cylinder.

                        I was suggesting to reduce the flow temperature on the boiler. The flow temperature adjustment on a boiler controls the temperature of the water it puts out that circulates through the radiators and through the indirect coil in the hot water cylinder.

                        Comment

                        • willdonal
                          Automated Home Sr Member
                          • Oct 2017
                          • 58

                          #72
                          Originally posted by DBMandrake View Post
                          That's your hot water cylinder.

                          I was suggesting to reduce the flow temperature on the boiler. The flow temperature adjustment on a boiler controls the temperature of the water it puts out that circulates through the radiators and through the indirect coil in the hot water cylinder.
                          Got you, I'll dig out the manual for the boiler. If I turned down the brass Knob would that not reduce the max temp the tank would get to before it switched off. Or the blue dial? thanks

                          Comment

                          • DBMandrake
                            Automated Home Legend
                            • Sep 2014
                            • 2361

                            #73
                            Originally posted by willdonal View Post
                            Got you, I'll dig out the manual for the boiler. If I turned down the brass Knob would that not reduce the max temp the tank would get to before it switched off. Or the blue dial? thanks
                            Maybe, but it's unclear from the pictures, and if it is wired wrong, which is quite likely, or the zone valve has a problem it may not have any effect.

                            Comment

                            • willdonal
                              Automated Home Sr Member
                              • Oct 2017
                              • 58

                              #74
                              Originally posted by DBMandrake View Post
                              Maybe, but it's unclear from the pictures, and if it is wired wrong, which is quite likely, or the zone valve has a problem it may not have any effect.
                              OK Thanks, I'll leave it to the expert next week. Cheers :-) :-)

                              Comment

                              • HenGus
                                Automated Home Legend
                                • May 2014
                                • 1001

                                #75
                                The amount of information that has built up on this forum over the past 4 years (in my case) is amazing. I have just found this snippet from Rameses:

                                @ 20c - legionella survive but dormant
                                @ 35-46c - legionella Perfect growth conditions
                                @ 50-54c - legionella lives but cannot multiply
                                @ 55c legionella dies within 5-6 hours
                                @ 60c legionella dies within 32 mins
                                @ 65c Legionella dies within 2 mins

                                I think that the OP can be certain that his cylinder does not have Legionella.

                                Comment

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