HR92's: A rant

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  • DJBenson
    Automated Home Jr Member
    • Feb 2016
    • 24

    HR92's: A rant

    I'm 100 miles from home, working away, and just received news that my toddler had pulled/knocked one of the HR92's in my house off the radiator valve leaving my daughters room with a radiator switched on fully and a distressed wife trying to sort out the situation. Now I'm not sure how much force a 14 month old can exert but I would expect not enough to rip a TRV off its body...not the case it seems

    For as long as I've had the Evohome system, I have been perplexed about Honeywell's choice of plastic screw versus metal which most other manufacturers (even in the smart heating arena) are using. Plastic on metal in a screw design just sounds like it should have been thrown out at the design phase but alas it wasn't. Not only that, but from what I can gather, said plastic part isn't available as a spare and as such a damaged screw section means a total replacement.

    Am I alone in my displeasure at this design? I can't be the only one who has suffered the loss of a HR92 due to accidental damage to the screw section - I imagine a decent knock with a vacuum or similar could cause such damage.

    And just to pick up on the spares issue - I would not mind so much paying for a replacement screw section, but I do have a problem when a £60 piece of kit is written off by damage to what must amount to pennies for the screw section. Having invested well over £1000 in my system, I expect some longevity, and that includes a) either being able to stand up to reasonable daily use (reasonable versus a "normal" TRV) or b) spare parts being available in the event of damage occurring.

    Rant over
  • DJBenson
    Automated Home Jr Member
    • Feb 2016
    • 24

    #2
    Ah, it seems The Evohome Shop now stock the spares which is great, I got my kit from there and they kindly sent me a replacement last time I had issues free of charge from one of their returns but at the time said Honeywell did not make them available as spares - glad to see that policy has changed and I can cope with seven quid rather than sixty.

    Rest of my rant stands however

    Comment

    • bruce_miranda
      Automated Home Legend
      • Jul 2014
      • 2307

      #3
      This was another reason I thought the HR92 was a step backwards from the HR80. All the parts that touched the TRV in the HR80 are metal. Also there are no pivoting screen etc to be worried about.

      Comment

      • The EVOHOME Shop
        Site Sponsor
        • Dec 2014
        • 483

        #4
        Originally posted by DJBenson View Post
        Ah, it seems The Evohome Shop now stock the spares which is great, I got my kit from there and they kindly sent me a replacement last time I had issues free of charge from one of their returns but at the time said Honeywell did not make them available as spares - glad to see that policy has changed and I can cope with seven quid rather than sixty.

        Rest of my rant stands however
        These may help also - https://theevohomeshop.co.uk/honeywe...ontroller.html

        Comment

        • paulockenden
          Automated Home Legend
          • Apr 2015
          • 1719

          #5
          Originally posted by The EVOHOME Shop View Post
          Does anyone else see Cybermen? or is it just my stupid brain?

          Comment

          • paulockenden
            Automated Home Legend
            • Apr 2015
            • 1719

            #6
            More seriously, won't that interfere with the heat sensing ability of the HR92?

            I'm guessing these are probably best used with a wall stat.

            Comment

            • The EVOHOME Shop
              Site Sponsor
              • Dec 2014
              • 483

              #7
              Originally posted by paulockenden View Post
              More seriously, won't that interfere with the heat sensing ability of the HR92?
              Honeywell designed and tested them, so I assume not...

              More like a storm trooper helmet in my eyes lol!

              Comment

              • DBMandrake
                Automated Home Legend
                • Sep 2014
                • 2361

                #8
                Originally posted by paulockenden View Post
                More seriously, won't that interfere with the heat sensing ability of the HR92?

                I'm guessing these are probably best used with a wall stat.
                Where is the temperature sensor inside the HR92 ? I've had one apart to repair a detached screen but I don't remember how it is laid out or whether there is a vent that would allow airflow through the the casing past a sensor.

                I also vaguely remember reading a datasheet back before I had evohome saying that the HR92 had two temperature sensors in it! But when I have looked recently I can't find any documents saying anything to this effect...

                Comment

                • paulockenden
                  Automated Home Legend
                  • Apr 2015
                  • 1719

                  #9
                  I remember Rameses saying the temperature sensing was designed to measure updraught.

                  or rather, I /think/ I remember that!

                  Comment

                  • The EVOHOME Shop
                    Site Sponsor
                    • Dec 2014
                    • 483

                    #10
                    Originally posted by DBMandrake View Post
                    Where is the temperature sensor inside the HR92 ? I've had one apart to repair a detached screen but I don't remember how it is laid out or whether there is a vent that would allow airflow through the the casing past a sensor.

                    I also vaguely remember reading a datasheet back before I had evohome saying that the HR92 had two temperature sensors in it! But when I have looked recently I can't find any documents saying anything to this effect...
                    I believe one is mounted on the back of the screen on the HR92 (may also have one on the PCB) and deffo PCB mounted on the HR91 (as it has no screen lol)...

                    Comment

                    • MrBoy
                      Automated Home Guru
                      • May 2017
                      • 165

                      #11
                      From only a few days use, the temperature sensors on the HR92 are wildly wrong in every room... They are frequently reading 20-21c when the room is 15c.

                      My radiators do run pretty hot; putting a sensor 1" away from 80c metal it's hard to see how it can work accurately.

                      Actually this might be a reason for plastic parts, to restrict heat conduction from the valve body?

                      Comment

                      • Ian_W
                        Automated Home Jr Member
                        • Dec 2017
                        • 13

                        #12
                        Originally posted by MrBoy View Post
                        From only a few days use, the temperature sensors on the HR92 are wildly wrong in every room... They are frequently reading 20-21c when the room is 15c.
                        There's a good discussion about this here, in particular see @DBMandrake's post #3.

                        When the room is at a steady state, I normally find the HR92s measure about 1C higher than a known-good thermometer in the middle of the room. This offset can be corrected on each HR92 individually using option 8 in the settings menu.

                        Comment

                        • Dan_Robinson
                          Automated Home Ninja
                          • Jun 2012
                          • 347

                          #13
                          Originally posted by MrBoy View Post
                          My radiators do run pretty hot; putting a sensor 1" away from 80c metal it's hard to see how it can work accurately.
                          Physics..... Convection.
                          Kind Regards - Dan Robinson (Jennings Heating Ltd)

                          Comment

                          • MrBoy
                            Automated Home Guru
                            • May 2017
                            • 165

                            #14
                            Originally posted by Dan_Robinson View Post
                            Physics..... Convection.
                            you might've been selling these things a decade but I've a degree in physics and that's not how it works. Radiators largely work by convection as we all know but they do radiate some heat and at close range this is significant... Hold your hand an inch from a hot radiator and you can feel it.
                            The TRV being at the side should minimise the effect, and at the bottom it might be partially mitigated by the cold air from the convection current being sucked back in but not fully.
                            Then of course your radiator transmits heat a third way... Physics... Conduction... But only to things touching it. Your valve body is likely to be roasting hot which will to some degree be conducted into the head. When I removed my old TRVs with metal fixings, some were so hot I could barely do it.

                            I guess a well ventilated radiator suffers less but sadly many are stuck in corners or next to things so the TRV is likely to end up in a pocket of unusually warm air. No physics can fix this... Move your rad, put the TRV in a better position, or get a room thermostat

                            Comment

                            • CT1
                              Automated Home Guru
                              • Apr 2016
                              • 189

                              #15
                              Initially the radiator will be hot and sensor will likely read high. As room gets nearer to the set temp radiator will be cooler and have less affect on sensor. Eventually a steady state will be reached with radiator only providing enough heat to maintain set temp and having less influence on sensor. Having the head set at 90 degrees to the radiator would be better than vertical orientation but looks unusual and is more vulnerable to being used as a foot hold for adventurous toddlers.

                              Comment

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