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Thread: Honeywell evohome and Vaillant ecotec plus 838

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  1. #34
    Automated Home Legend
    Join Date
    Sep 2014


    Quote Originally Posted by freddyq View Post
    - TRV installation was slightly trickier. I didn't need any adapter for my radiator valves as they were already the right measurement bit I found in some cases the part of the TRV which screws on to the radiator had a tendency to over-screw very easily. If you do that, then it's likely the trv won't be able to open and close the radiator properly. After a bit of messing around I managed to get the TRVs installed. When I turned a particular zone on for the first time I noticed radiators not in that zone were still getting slightly warm, i.e. The trv wasn't screwed in far enough so the radiator valve wasn't being fully closed. I went round and slightly tightened the screw slightly so that the trv would fully close the valve but not so much that the TRV's motorised function would find it too stiff to close. Also, the pin on the radiator only need to depress a couple of mm so that's another reason why you need to get the screwing of TRVs right. I also tested the screwing by rotating the black part of the trv clockwise until it got to the end, i.e. to replicate the valve being closed. By doing this I could test how stiff it felt to close the valve and therefore whether the trv would be able to close it properly or not. Anyway, once I figured out what the trv would be doing and tweaked it's positioning, the radiators were all being turned fully on and fully off as expected.
    Although you're saying that its easy to over tighten the adaptor the symptoms you describe are actually those of not screwing it on enough. Don't worry about it not being able to open the valve fully - the HR92 has a pin travel range of 4mm which should be plenty for most valves. Nor does screwing the adaptor on more make it "too stiff" for it to close. The only real danger of screwing the adaptor on too tight is splitting the adaptor - after all you're screwing a plastic threaded adaptor onto a metal thread, if it's over tightened the plastic would break or strip, so you want to judge the tightening torque and not be too ham fisted.

    The way I do it is screw it on approximately by hand first, then sit the HR92 in place and turn the HR92 body to "nip up" the thread as if it was a screwdriver. It's a lot harder to judge how tight the thread is if you turn the adaptor by hand but turning the HR92 body gives a lot better sense of how tight it is and where it starts to bite and start resisting turning. If you can undo it by bumping the HR92 with the screen strut in place then its too loose.

    The HR92 has a calibration process that it performs when you click the locking tab shut where it will try to wind the pin right down until the exerted force reaches a certain limit - by doing this it "explores" how much travel the pin has so that it knows where closed and open are and that gives it its working range. If the threads are screwed on firmly and you still find it struggles to close the valve fully (radiator heating when other zones call for heat, as you describe) you might need full stroke mode enabled - this increases the torque applied to the motor when closing the valve, but also increases how far it tries to open the valve, but at the expense of reduced battery life.

    If it still doesn't shut them off properly either you have stiff/sticky valves or they're not 100% compatible. I've got some cheap Peggler Bulldog valves on my radiators (the TRV heads that the HR92 replaced were horrible) and while I don't have any problems with the HR92's closing the valves, I have noticed on a couple of them that the valve doesn't fully open until the black wheel the HR92 turns is virtually fully unwound and at the limit stop, so I've had to set these two to full stroke mode in the cold weather as it wasn't fully turning on the radiator. I'm going to try filing a tiny bit off the top of the pin to see if I can fix that....
    My only question is that I'm not sure how the controller would be mounted on the wall because it's power supply connector is on the back of the stand, rather than controller itself. Unless there is a connector on the back of the controller too which I didn't notice? I don't think the wiring for my old manual wall thermostat is sufficient to power the controller anyway but I'm just wondering nonetheless.
    There is a separately sold wall mount which I use. The Evotouch is designed to be powered all the time so I'm not a fan of the dock. I have ours on the wall in the hallway where the old stat used to be and its the perfect place as its a nexus of travel through the ground floor of the house so easy to catch a glance of as you pass or get to when you need to.

    The wall mount comes with a small transformer a bit bigger than a box of matches - you can either keep this behind the wall mount and bring 240v mains to the mount (but then you require a normal depth electrical back box behind it) or you can fit the plate more or less flush on the wall with a low voltage cable coming out of the wall and put the transformer at the far end - that's what I elected to do to save digging a load of plaster out of the wall and fitting a back box. I actually managed to squeeze the transformer inside my wiring centre box for a nice neat installation and send the low voltage (5v) across the cable that used to go to the old wall stat.
    Last edited by DBMandrake; 21st November 2016 at 10:56 AM.

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