Evohome firmware 02.00.19.31 Beta Trial - Exclusive for Automated Home Members

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • DBMandrake
    Automated Home Legend
    • Sep 2014
    • 2361

    Originally posted by bruce_miranda View Post
    Years ago, @DBMandrake came up with the brilliant idea to have the CH Valve open with the pump, rather than be controlled by Evohome. Best mod I made. It allows the CH Valve to open and close and hence not seize but more importantly it circulates the heat through the loop in pump over run mode. it also takes care of boiler frost protection too. I love the idea, so simple and effective.
    Did you wire in hot water priority as well ? Or are all you radiators HR92 controlled to prevent radiators heating during hot water reheat ?

    While that original idea of mine is better than just mechanically locking the heating zone valve open, (it allows full flow and also occasionally exercises the valve to stop seizing) I prefer the scheme I show in the circuit diagram above, as it is equivalent to what you are doing except when hot water reheating is enabled, at which point it reverts to normal TPI to prevent radiators going over temperature. Of course if you have hot water priority this isn't needed.

    The above circuit is a further logical progression from the original idea to run the heating zone valve from the pump.
    Last edited by DBMandrake; 3 April 2020, 10:51 PM.

    Comment

    • mtmcgavock
      Automated Home Legend
      • Mar 2017
      • 507

      Originally posted by DBMandrake View Post
      I don't have any radiators without HR92's anymore, so not in my situation no.

      You're right though - if you did have a bypass radiator then at the end of a hot water reheat cycle in summer a small amount of latent heat from the boiler heat exchanger would be dumped into that cold bypass radiator, however that's a good thing for the boiler, and it would barely be enough to make the radiator luke warm and would only occur once at the end of each hot water reheat cycle. (The heating zone valve would stay closed until the hot water zone valve closed and the boiler stopped firing - then it would open when there was only latent heat remaining)

      When I did have a bypass radiator it barely warmed at all from the heat dump due to the relatively high thermal mass of the radiator vs boiler heat exchanger.

      Now that I have all HR92 controlled radiators I rely on a one minute hot water overrun to allow latent heat to dissipate at the end of the hot water reheat cycle.
      All my rads have HR92s too, so I think a timer on my Heating MV would just be sufficient for when there’s an overrun from a heating demand - any pointers for what timer you used?

      I use a 2 minute overrun on HW, plus the bypass rad in the garage for when there’s no heat demand for the CH.

      Comment

      • DBMandrake
        Automated Home Legend
        • Sep 2014
        • 2361

        Originally posted by Andy the Minion View Post
        Simon i replied to your pm but was told you broke your mailbox and need to clear some space
        Just checked and I only had 28 messages in my inbox. Not much room on this forum! I've deleted them all so try again.

        Comment

        • DBMandrake
          Automated Home Legend
          • Sep 2014
          • 2361

          Originally posted by mtmcgavock View Post
          All my rads have HR92s too, so I think a timer on my Heating MV would just be sufficient for when there’s an overrun from a heating demand - any pointers for what timer you used?

          I use a 2 minute overrun on HW, plus the bypass rad in the garage for when there’s no heat demand for the CH.
          I used an MRT16-REM:



          It fits a regular protruding back box and has a blank front panel. A version with volt free contacts is availble but if you're just switching 240v AC the standard version is fine. The mode should be set to overrun mode and the delay can be configured anywhere from about 5 seconds to an hour, so it's quite versatile. Not sure how easy it will be to get hold of one in the current climate though!

          My boiler is so old it didn't have any pump overrun at all - so this is my retrofit pump overrun. (An old boiler with no pump overrun really doesn't like TPI I discovered!)

          Comment

          • roydonaldson
            Automated Home Guru
            • Jan 2013
            • 205

            Just got up this morning to find Bedroom Zone set to 35C.......and Living Room set to 19C, reading 15.5C, zone says calling for 100% heat, and yet Zone Valves are off and not pumping at boiler....

            Roy.20200404_072012.jpg
            Last edited by roydonaldson; 4 April 2020, 09:32 AM.

            Comment

            • AlexP
              Automated Home Jr Member
              • Feb 2016
              • 10

              Originally posted by roydonaldson View Post
              Just got up this morning to find Bedroom Zone set to 35C.......and Living Room set to 19C, reading 15.5C, zone says calling for 100% heat, and yet Zone Valves are off and not pumping at boiler....

              Roy.[ATTACH=CONFIG]1526[/ATTACH]
              Same again here. And this time not to do with optimum start. Maybe it coincided with optimum stop... uncertain on that. Either way it’s ideal.

              That’s at least 3 of us with this issue now so hopefully they might be able to gather enough information to work out what is going on... Andy?

              Comment

              • AlexP
                Automated Home Jr Member
                • Feb 2016
                • 10

                Originally posted by mtmcgavock View Post
                Surely with this though in the summer you get heat into any rads with no HR92s?

                It is something i'm going to have to implement though, i'm just getting a lot of wasted heat - my rad in my garage acts as a bypass so all the heat is going into there.
                I have a similar setup here. Hot water is not under the control of evohome - I retained the old programmer for that, initially due to cost and then partly because of the issues some reported here. It didn’t seem to offer enough additional usability to be worth the outlay.

                So I just have a single bdr91 as a boiler relay. Our boiler was an ancient ideal Mexico and I added the overrun timer for 2 reasons. One because it seemed that there was a lot of latent heat in the boiler going to waste (through the flu and into the cupboard that the boiler was housed in). Also because the constant cycling of the pump and CH valve was annoying.

                We have recently had the boiler replaced with a WB which has its own pump and overrun. I have retained the timer circuit simply to hold the valve open for long enough for the boiler to complete its overrun and also to stop the valve cycling when the tpi is at its lowest setting.

                As described above I have also arranged so any HW demand will cause the CH valve to close immediately that there is no TPI demand. When the HW demand is satisfied, the overrun is diverted back through the CH circuit.

                All our roads either have HR92 or old fashioned TRVs so there is little or no undesired hearing in the summer, although it does mean that the bathroom towel rails get warm in the mornings which is useful for drying towels in the summer and means we don’t have to use the electric side of the rails. At least it did with the old boiler and it’s massive heat exchanger. It remains to be seen if the new boiler will retain enough heat to make any real difference.

                Happy to post the schematic here is it is useful to anyone.

                Comment

                • roydonaldson
                  Automated Home Guru
                  • Jan 2013
                  • 205

                  Originally posted by AlexP View Post
                  Same again here. And this time not to do with optimum start. Maybe it coincided with optimum stop... uncertain on that. Either way it’s ideal.

                  That’s at least 3 of us with this issue now so hopefully they might be able to gather enough information to work out what is going on... Andy?
                  I have no heat in the downstairs of my house. All downstairs zones are below there setpoints, EvoHome controller shows all these zones calling for 100% heat, yet the BDR91 zone valve at the boiler is off and has been for the last 2 hours.

                  Andy - can someone please look at his urgently.......or revert my controller.

                  Comment

                  • mtmcgavock
                    Automated Home Legend
                    • Mar 2017
                    • 507

                    Originally posted by AlexP View Post
                    I have a similar setup here. Hot water is not under the control of evohome - I retained the old programmer for that, initially due to cost and then partly because of the issues some reported here. It didn’t seem to offer enough additional usability to be worth the outlay.

                    So I just have a single bdr91 as a boiler relay. Our boiler was an ancient ideal Mexico and I added the overrun timer for 2 reasons. One because it seemed that there was a lot of latent heat in the boiler going to waste (through the flu and into the cupboard that the boiler was housed in). Also because the constant cycling of the pump and CH valve was annoying.

                    We have recently had the boiler replaced with a WB which has its own pump and overrun. I have retained the timer circuit simply to hold the valve open for long enough for the boiler to complete its overrun and also to stop the valve cycling when the tpi is at its lowest setting.

                    As described above I have also arranged so any HW demand will cause the CH valve to close immediately that there is no TPI demand. When the HW demand is satisfied, the overrun is diverted back through the CH circuit.

                    All our roads either have HR92 or old fashioned TRVs so there is little or no undesired hearing in the summer, although it does mean that the bathroom towel rails get warm in the mornings which is useful for drying towels in the summer and means we don’t have to use the electric side of the rails. At least it did with the old boiler and it’s massive heat exchanger. It remains to be seen if the new boiler will retain enough heat to make any real difference.

                    Happy to post the schematic here is it is useful to anyone.
                    Thanks, yes it's something I need to do as had been thinking it for a long time and it looks like a few members have done this.

                    Mines a little more complex though, as I have 2 heating zones (Rad & Towel Rail Circs), along with HW. On top of that I have HW priority which I can turn on and off as required, then I can have the Towel Rail zones coming on with the HW via a relay in summer (Again selectable for On/Off).

                    So think i'll have to have a sit down and think of the best way of doing this, it isn't as simple as just adding a timer in. And as DBmandrake and yourself say you want the CH valve to close on a HW demand.

                    Comment

                    • mtmcgavock
                      Automated Home Legend
                      • Mar 2017
                      • 507

                      Just for feedback - no issues with set points at my end so far.

                      Comment

                      • DBMandrake
                        Automated Home Legend
                        • Sep 2014
                        • 2361

                        Originally posted by mtmcgavock View Post
                        So think i'll have to have a sit down and think of the best way of doing this, it isn't as simple as just adding a timer in. And as DBmandrake and yourself say you want the CH valve to close on a HW demand.
                        Well in my case I don't just want the CH valve to close on hot water demand - because that would be hot water priority, which I don't want. I just want it to come back under TPI control from the heating relay.

                        The reasoning for my arrangement is that when there is no hot water demand the boiler relay will cycle on and off with TPI based on heating demands - in this condition I want the heating zone valve to remain open to allow continuous water flow to radiators (ignoring the heating relay TPI) while the boiler cycles on and off with TPI to modulate heat output.

                        However during a hot water reheat cycle the boiler relay will turn on continously regardless of heating demand, in this condition I want the heating zone valve to revert to TPI modulation so that despite the boiler running continuously and reaching its flow temperature set point heat transfer to the radiators can be modulated down to approximately what it was before by making the flow to them intermittent under TPI control.

                        The flow temperature is higher but the intermittent flow should cause total heat transfer to roughly even out, and this is better than just letting it flow continously during a hot water reheat (radiators will go over temperature due to increased flow temperature) or shutting it down completely like hot water priority. (Radiators wil go cold over time and newly opening radiators won't heat up as in the bathtub scenario..)
                        Last edited by DBMandrake; 4 April 2020, 10:27 AM.

                        Comment

                        • AlexP
                          Automated Home Jr Member
                          • Feb 2016
                          • 10

                          Originally posted by DBMandrake View Post
                          Well in my case I don't just want the CH valve to close on hot water demand - because that would be hot water priority, which I don't want. I just want it to come back under...
                          Sorry, This is actually the setup I have too - I just worded it badly. I think essentiallly we have the same logical setup.

                          Comment

                          • mtmcgavock
                            Automated Home Legend
                            • Mar 2017
                            • 507

                            Originally posted by AlexP View Post
                            Sorry, This is actually the setup I have too - I just worded it badly. I think essentiallly we have the same logical setup.
                            Think you’ve misunderstood me too - I was meaning when there’s a HW demand and no CH demand. You don’t want the CH valve open on timer then, during a dual demand (HW & CH) then yes you’ll want both open - if you haven’t got HW Priority

                            Comment

                            • kevinsmart
                              Automated Home Ninja
                              • Sep 2018
                              • 257

                              No problems seen so far with the new firmware and my OpenTherm, DHW priority, UFH mixer valve setup.

                              New features appear complementary to my OTGW based weather compensation, which is good.

                              Comment

                              • zxdavb
                                Automated Home Guru
                                • Jan 2018
                                • 106

                                Originally posted by Andy the Minion View Post
                                Okay, no promises but I will ask what the effort is in testing (thats where the time issue is) and see if it can be snuck in.
                                @Andy the Minion,

                                I am the maintainer for the evohome (actually the TCC) integration for Home Assistant

                                On my to-do list, due to repeated/high demand from people using the integration, is to emulate an economy mode with a variable offset, from (say) 1-3 C.

                                In short, 3 C is too much, and thus economy mode is not being used as much as it might me.

                                Comment

                                Working...
                                X