Heat pumps with evohome

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  • sandyman
    Automated Home Sr Member
    • Mar 2016
    • 85

    #16
    Originally posted by spiralp View Post
    An update to my earlier experience of using Evohome with a Panasonic heat pump. My installer has decided the two products are not compatible and has completely disengaged all Evohome control of the heat pump. All my Evohome now does is control the TRVs. The heat pump decides as and when to produce heat and at what temperature based on a weather compensation curve. This has eliminated cycling and significantly improved my heat pump efficiency. I am now of the opinion that heat pumps are best controlled by radiator sizing, radiator balancing and flow temperature (weather compensated).
    that maybe makes sense for the flow temperature contorl but - how does the heatpump know that it needs to come on in the first place? there must be something?

    Comment

    • spiralp
      Automated Home Lurker
      • Nov 2020
      • 6

      #17
      The heat pump has its own controls. There is a simple on/off for heating at whatever external temperature I set. Mine is set at 18deg, below which temperature the heat pump is ready to provide heat. The heat pump also has a weather compensation curve, which sets the heating flow temperature depending on external temperature, mine is set to 48deg at -5deg reducing to 32deg at +15deg. The heat pump heats a 30 litre buffer tank and monitors the deltaT of the flow to the buffer tank, only providing heat when necessary. Hence if the external temperature is, say, 16 deg the heat pump is ready to operate. However, if the house is quite warm (such that the deltaT is below 5deg) then no heat is provided. The heating circulation pump is controlled by both pressure and by the heat pump. Most of my Evohome TRVs are now set to wide open, but with balancing via the lockshield valves, and provide the correct room temperature as a result of the weather compensated flow temperature. A few of my Evohome TRVs are used as limiters to avoid some rooms getting too hot (e.g. on days when there is significant solar gain). To put it simply, the heat pump is on all the time. There is a timer function, but I do not use this.

      Comment

      • MikeyMan
        Automated Home Jr Member
        • Nov 2020
        • 10

        #18
        Originally posted by The evo Geek View Post
        Hi all,

        I noticed how little chatter there seems to be about using evohome with heat pumps. I thought it would be interesting to share information from those of us that do (there are some of us out there!). With heat pumps becoming more and more the norm, it would be useful to share good (and bad?) practice for heat pump system setup and optimisation with evohome.
        So, I've got a few questions to help share relevant information:
        1. What type of heat pump - ASHP, GSHP, WSHP, EAHP? I'm afraid i don't know these terms. I've got an Air to air monobloc
        2. Make / model of heat pump Panasonic WH-MXC09J3E8, three phase T-Cap model
        3. Heat pump controller make / model (if known, or separate to HP) Integrated? Or Evohome?
        4. Heat pump compressor type - fixed speed or inverter Must surely be Inverter
        5. Buffer yes/no? If yes, buffer size and configuration - 2 (balanced/unbalanced), 3 or 4 pipe No buffer as of yet
        6. Direct heat pump control by evohome, or not? Currently no, tried it, but was not working well
        7. Number of evohome zones? 6
        8. Type of zones and quantity - TRV, UFH, Zone valve, other two zones on valve, one on the HCE
        9. Typical daytime/nightime setbacks across zones? 1 degree at the moment
        10. DHW provided by heat pump? If yes, hot water control by evo or heat pump controller? Yes, internal controller
        11. If valves used for heating and/or DHW, 2 port, 3 port diverter, 3 port mixer (eg Y plan type)? Three way valve controlled by internal controller
        12. Heat pump controller settings - room control? None, one external thermostat
        13. Heat pump controller settings - other configuration changes?
        14. Property type, and approx floor area - flat/apartment/terraced/townhouse/semi/detached/bungalow/other Detached, 210m2
        15. Other relevant information, comments and observations


        Hope this proves useful catalyst to information exchange for those using heat pumps with evo and those going that way in the future.

        Vaughn.

        Tried to fill in to the best of my abilities. Till now i've been happy with EvoHome in combination with my Gas heating. However, things changed after switching to the heatpump.

        First of all; very disappointing to have to buy a BRD91T for these -in my opinion- purely software changes. This could have been solved differently. Also; having to buy a second BRD91T to enable cooling is frankly rediculous. Should have changed the hardware and made a threeway relay of it.

        Second; very disappointing in the way EvoHome is trying to control the heatpump. It seems limited to a one hour horizon, thus resulting in -at best- one cycle per hour. While i would have liked to see hour long runs. Or at least that's what EvoHome should be asking.

        Trying to figure out if i'm hanging on to the system, in which i invested close to a thousand euros in the past years.

        Frankly, i'm currently thinking of getting rid of it.

        Comment

        • sandyman
          Automated Home Sr Member
          • Mar 2016
          • 85

          #19
          so if I understand you correctly, you've got an external stat (part of the heat pump vendor's controller or something else?) that calls for heat from the heatpump, and then entirely separate from that the evohome controller opens and closes TRV's according to your schedule? would I be right to say that if Evohome wants heat in a particular less-used room but the heatpump stat isn't calling because its not in that particular room, you get no heat there because evohome has no way to actually call for heat any more?

          I guess the reverse (heat pump calls, evohome doesn't) is be easier to avoid because you can locate the heatpumps stat in a communal / frequently used room and program it the same as your evohome schedule in that room?

          and am I right to say that previously you tried the evohome BDR calling for heat directly from the heat pump and that gave poor behaviour of the heatpump? can you expand any more on what you tried, what behaviour you saw?

          your house is exactly same size as mine I've got 22 rads and over £1500 worth at today's prices of HR92's, I love the per-room control and do not want to lose it, our rooms are really not all the same so going back to a single stat for the house and "normal" TRV's is not what I want! really trying to go heat pump but not able to find a good answer to this control problem.

          did you consider a 3 or 4 pipe buffer or an LLH - any option that separates primary and secondary sides? in which case: evohome calls for heat from buffer on secondary side, buffer calls for heat from heat pump on primary side, seems to be a possible option?

          Comment

          • kevinsmart
            Automated Home Ninja
            • Sep 2018
            • 257

            #20
            I guess Evohome will work better with a buffer tank.

            Heat pump will independently be responsible for heating the buffer to a weather compensated temperature.

            Evohome will control the flow pump based on aggregated zones’ demand.

            Comment

            • MikeyMan
              Automated Home Jr Member
              • Nov 2020
              • 10

              #21
              Originally posted by sandyman View Post
              so if I understand you correctly, you've got an external stat (part of the heat pump vendor's controller or something else?) that calls for heat from the heatpump, and then entirely separate from that the evohome controller opens and closes TRV's according to your schedule? would I be right to say that if Evohome wants heat in a particular less-used room but the heatpump stat isn't calling because its not in that particular room, you get no heat there because evohome has no way to actually call for heat any more?
              My apologies. Evohome functions as the external thermostat setting. Thats the way it is called on the panasonic settings. However, at this point, i'm using the 'water temperature' mode. Which puts the thermostat out of play. So effectively Evohome is now only steering the zones.

              I guess the reverse (heat pump calls, evohome doesn't) is be easier to avoid because you can locate the heatpumps stat in a communal / frequently used room and program it the same as your evohome schedule in that room?
              Thats kind of how it is working now. Far from ideal, but i want to do some more measurement on the way Evohome is calling for heat now.


              [evohome]
              and am I right to say that previously you tried the evohome BDR calling for heat directly from the heat pump and that gave poor behaviour of the heatpump? can you expand any more on what you tried, what behaviour you saw?
              [/quote]

              Tried that for a couple of days. But behaviour was very erratic.
              WP Steering.png

              This is the way evohome is calling for heat. This can never result in long runs.

              your house is exactly same size as mine I've got 22 rads and over £1500 worth at today's prices of HR92's, I love the per-room control and do not want to lose it, our rooms are really not all the same so going back to a single stat for the house and "normal" TRV's is not what I want! really trying to go heat pump but not able to find a good answer to this control problem.
              I've got underfloor heating all over. 10 cm distance max, 16mm. Main reason for still wanting room control is that i have full glass on the north and south sides of my house. This results in very large temperature differences between the two front and two back sleeping rooms.
              It would be enough for me to have the heatpump run free all day, and just shut off the rooms that are too hot.
              That's why i'm starting to think about dropping evohome.

              did you consider a 3 or 4 pipe buffer or an LLH - any option that separates primary and secondary sides? in which case: evohome calls for heat from buffer on secondary side, buffer calls for heat from heat pump on primary side, seems to be a possible option?
              Buffer would probably fix some. However, if evohome keeps calling in one hour time brackets, steering is still very poor for heatpump appications.

              Comment

              • MikeyMan
                Automated Home Jr Member
                • Nov 2020
                • 10

                #22
                Originally posted by kevinsmart View Post
                I guess Evohome will work better with a buffer tank.

                Heat pump will independently be responsible for heating the buffer to a weather compensated temperature.

                Evohome will control the flow pump based on aggregated zones’ demand.
                That would probably solve part of the puzzle. However, i still think the steering should be changed.

                Comment

                • kevinsmart
                  Automated Home Ninja
                  • Sep 2018
                  • 257

                  #23
                  The cycle rate can be increased with a buffer tank and secondary pump.

                  For your inverter pump I guess you might be able to run 2 cycles per hour.

                  Comment

                  • MikeyMan
                    Automated Home Jr Member
                    • Nov 2020
                    • 10

                    #24
                    Originally posted by kevinsmart View Post
                    The cycle rate can be increased with a buffer tank and secondary pump.

                    For your inverter pump I guess you might be able to run 2 cycles per hour.

                    https://ensupport.getconnected.honey...language=en_US
                    With a heatpump you'd rather have 1 cycle per two hours. Or more. That's the whole issue

                    Comment

                    • sjmcguckin
                      Automated Home Lurker
                      • Oct 2022
                      • 7

                      #25
                      In June I had a Stiebel-Eltron heat pump installed with a 200L buffer tank and a DHW tank.

                      I also installed Jaga Strada Hybrid radiators which can provide heating and cooling.
                      The Stiebel-Eltron controller manages the heat pump based on a weather curve and also enables me to switch between cooling and heating. In heating mode it sets the target heat for the buffer tank based on the weather curve which basically keeps the buffer tank to a temperature of 5% above or below the target temperature. In cooling mode it keeps the buffer tank chilled to just above the dew point. It keeps the DHW tank to (user defined) set temperature in both heating and cooling mode. I have the heat pump programmed to function between 6am and 10pm. The rest of the time it is effectively off.

                      The radiators are feed by the buffer tank and controlled by evohome. The evohome system is set up with twelve zones and when any zone requires heat (or cooling) the heating circuit pump is activated via a BDR. One of the zones is underfloor heating which is also activated by a BDR. All the other zones are activated by an HDR92.
                      So far I have found this set up to work very well.

                      However I do have one evohome question. In one of the rooms I have three radiators. Each radiator is fitted with an HDR92. I want the three radiators to combine to provide a consistent and constant heat throughout the room (ie. no hot or cold spots). To achieve this I have bound the three HDR92s to a single zone wireless thermostat which should regulate the temperature. I can change the target temperature setting on the HDR92s by using the single zone thermostat. However the actual room temperature showing on the HDR92s and the controller is different to the temperature showing on the thermostat and when the HDR92s reach the target temperature they switch off even if the thermostat is below the target.
                      Has anyone come across this issue and is there a solution?

                      Comment

                      • MikeyMan
                        Automated Home Jr Member
                        • Nov 2020
                        • 10

                        #26
                        Originally posted by sjmcguckin View Post
                        In June I had a Stiebel-Eltron heat pump installed with a 200L buffer tank and a DHW tank.

                        I also installed Jaga Strada Hybrid radiators which can provide heating and cooling.
                        The Stiebel-Eltron controller manages the heat pump based on a weather curve and also enables me to switch between cooling and heating. In heating mode it sets the target heat for the buffer tank based on the weather curve which basically keeps the buffer tank to a temperature of 5% above or below the target temperature. In cooling mode it keeps the buffer tank chilled to just above the dew point. It keeps the DHW tank to (user defined) set temperature in both heating and cooling mode. I have the heat pump programmed to function between 6am and 10pm. The rest of the time it is effectively off.

                        The radiators are feed by the buffer tank and controlled by evohome. The evohome system is set up with twelve zones and when any zone requires heat (or cooling) the heating circuit pump is activated via a BDR. One of the zones is underfloor heating which is also activated by a BDR. All the other zones are activated by an HDR92.
                        So far I have found this set up to work very well.

                        However I do have one evohome question. In one of the rooms I have three radiators. Each radiator is fitted with an HDR92. I want the three radiators to combine to provide a consistent and constant heat throughout the room (ie. no hot or cold spots). To achieve this I have bound the three HDR92s to a single zone wireless thermostat which should regulate the temperature. I can change the target temperature setting on the HDR92s by using the single zone thermostat. However the actual room temperature showing on the HDR92s and the controller is different to the temperature showing on the thermostat and when the HDR92s reach the target temperature they switch off even if the thermostat is below the target.
                        Has anyone come across this issue and is there a solution?
                        Room thermostat and HDR92 are probably not in the same location, i assume.
                        So calibrating the HDR92 for the values to match is a solution. Although 100% match willprobably be difficult.

                        Comment

                        • sjmcguckin
                          Automated Home Lurker
                          • Oct 2022
                          • 7

                          #27
                          Originally posted by MikeyMan View Post
                          Room thermostat and HDR92 are probably not in the same location, i assume.
                          So calibrating the HDR92 for the values to match is a solution. Although 100% match willprobably be difficult.
                          Hi MikeyMan,

                          Yes, I have the room thermostat in the coolest position in the room and I would like to have it control the three radiators. When you suggest calibration do you mean simply adjusting the temperature on the room thermostat or is there a more sophisticated way to calibrate them?

                          Comment

                          • MikeyMan
                            Automated Home Jr Member
                            • Nov 2020
                            • 10

                            #28
                            Originally posted by sjmcguckin View Post
                            Hi MikeyMan,

                            Yes, I have the room thermostat in the coolest position in the room and I would like to have it control the three radiators. When you suggest calibration do you mean simply adjusting the temperature on the room thermostat or is there a more sophisticated way to calibrate them?
                            If i'm correct, you can change the reading by up to two degrees plus or minus.

                            Comment

                            • lloyd
                              Automated Home Guru
                              • Oct 2020
                              • 160

                              #29
                              Originally posted by sjmcguckin View Post
                              In June I had a Stiebel-Eltron heat pump installed with a 200L buffer tank and a DHW tank.

                              I also installed Jaga Strada Hybrid radiators which can provide heating and cooling.
                              The Stiebel-Eltron controller manages the heat pump based on a weather curve and also enables me to switch between cooling and heating. In heating mode it sets the target heat for the buffer tank based on the weather curve which basically keeps the buffer tank to a temperature of 5% above or below the target temperature. In cooling mode it keeps the buffer tank chilled to just above the dew point. It keeps the DHW tank to (user defined) set temperature in both heating and cooling mode. I have the heat pump programmed to function between 6am and 10pm. The rest of the time it is effectively off.

                              The radiators are feed by the buffer tank and controlled by evohome. The evohome system is set up with twelve zones and when any zone requires heat (or cooling) the heating circuit pump is activated via a BDR. One of the zones is underfloor heating which is also activated by a BDR. All the other zones are activated by an HDR92.
                              So far I have found this set up to work very well.

                              However I do have one evohome question. In one of the rooms I have three radiators. Each radiator is fitted with an HDR92. I want the three radiators to combine to provide a consistent and constant heat throughout the room (ie. no hot or cold spots). To achieve this I have bound the three HDR92s to a single zone wireless thermostat which should regulate the temperature. I can change the target temperature setting on the HDR92s by using the single zone thermostat. However the actual room temperature showing on the HDR92s and the controller is different to the temperature showing on the thermostat and when the HDR92s reach the target temperature they switch off even if the thermostat is below the target.
                              Has anyone come across this issue and is there a solution?
                              I have a very similar setup - 3x HDR91, 1xDTS92, all existing as one zone. However, it sounds like I am seeing the behaviour that you are looking for, rather than the one you are seeing. Take this set of data from this morning. Setpoint is 19, and the three TRVs are showing 18.1, 17.3 and 20.2, and TRV3 has not shutdown even though it is well above the room target temperature.

                              Capture.JPG


                              Sounds like you may have set the zone up as multi-room rather than single-room?

                              Comment

                              • sjmcguckin
                                Automated Home Lurker
                                • Oct 2022
                                • 7

                                #30
                                Originally posted by lloyd View Post
                                I have a very similar setup - 3x HDR91, 1xDTS92, all existing as one zone. However, it sounds like I am seeing the behaviour that you are looking for, rather than the one you are seeing. Take this set of data from this morning. Setpoint is 19, and the three TRVs are showing 18.1, 17.3 and 20.2, and TRV3 has not shutdown even though it is well above the room target temperature.

                                [ATTACH=CONFIG]1952[/ATTACH]


                                Sounds like you may have set the zone up as multi-room rather than single-room?
                                Yes, that's eaxctly the behaviour I'm looking for. I have an extra single zone thermostat which is supposed to control the overall temperature in the room. However the HDR92s will switch off even if this thermostat is below the target. How did you set up your arrangement. I was told to first of all assign the single zone thermostat to the zone and the subesquently add the HDR92s.

                                Comment

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