Ultima357 Posted January 23, 2021 Author Share Posted January 23, 2021 17 hours ago, wozza said: I have 5 of these stats and I do not appear to suffer any of the issues that you have. I spent a lot of time checking for the best location for 4 of them and also confirmed that they were suitably accurate with a couple of digital thermometers over a period of a few weeks. Have you tried swapping the stat that is reading high for one that is reading ok to see if the problem moves with it? Heatmiser do a wall plate / surround for the V2 stat - not sure if it would help. In discussion with Heatmiser they were saying it's because my walls are insulated stud construction, so heat is not disappating from the psu, coupled with my passive super airtight build. If yours are in solid walls and you have a higher air movement then I'd expect the self heating to be less. I've pointed out to Heatmiser that stud walls have to be acoustically insulated according to building regs, so they should sort their design out to cope. Irrespective of this, having some additional ventilation in the faceplate would be good practice. Link to comment Share on other sites More sharing options...
wozza Posted January 23, 2021 Share Posted January 23, 2021 5 hours ago, Ultima357 said: In discussion with Heatmiser they were saying it's because my walls are insulated stud construction, so heat is not disappating from the psu, coupled with my passive super airtight build. If yours are in solid walls and you have a higher air movement then I'd expect the self heating to be less. I've pointed out to Heatmiser that stud walls have to be acoustically insulated according to building regs, so they should sort their design out to cope. Irrespective of this, having some additional ventilation in the faceplate would be good practice. I have 2 stats controlling UFH that are fitted to metal boxes that are screwed to internal block / brick wall with dot and dab plasterboard. I have another 2 stats controlling UFH - both are fitted into metal boxes in acoustically insulated stud walls (12.5mm plasterboard, timber construction with 100mm rockwool RWA45) - one of them is using just the floor probe. The last stat controls the radiators and is fitted in a plastic drywall box into a paramount plasterboard wall. We don't have a large amount of airflow as far as I know - the rooms have constant trickle ventilation and hold their temperature well - since reading your first post I have placed one of my digital thermometers close to the stat that gets the most movement past it (its adjacent to the integral garage door - its in a metal box screwed to brick wall) and I don't see any significant temp variation. Are your stats mounted in plastic or metal boxes? Fingers crossed that I don't get the issues that you have, please keep us updated on how it goes. Link to comment Share on other sites More sharing options...
Ultima357 Posted January 23, 2021 Author Share Posted January 23, 2021 3 hours ago, wozza said: Fingers crossed that I don't get the issues that you have, please keep us updated on how it goes. Well hopefully you don't. I didn't notice this until the one day I turned the MVHR off due to a neighbour bonfire and saw the jump in stat temps. Anyway, now SOLVED ?. The thread correspondence showed me a single gang spacer. So brought some today. Attacked with 8mm router to make slots and now temperature variation is cured. Note when I took the head off, laid it adjacent whilst I fitted this up and then put back, it kicked off with a temperature offset of nearly 2 degs to what it had been reading in situ. So see pictures. I've done one as shown and another with slots adjacent to the wall. Both seem to work well. Temperature measured by top slot is 2 deg more than room temperature. 2 1 Link to comment Share on other sites More sharing options...
ProDave Posted January 23, 2021 Share Posted January 23, 2021 That's very neat. It seems to me the REAL fault is the lack of side vents in the original thermostat casing. Not a lot of point in putting slots in the bottom with none anywhere else to let the air flow through. Sometimes I do seriously despair of people that "design" some stuff. I bet someone omitted them because it spoiled the look, sod the performance. Link to comment Share on other sites More sharing options...
MJNewton Posted January 23, 2021 Share Posted January 23, 2021 21 minutes ago, ProDave said: Not a lot of point in putting slots in the bottom with none anywhere else to let the air flow through. That said, many stats don't have slots in at all eg Nest and I think the Honeywell CM927 and Dt90 from memory. But then they don't have internal PSUs - I think *that's* the real design flaw. You should never create the very thing you're trying to measure. Link to comment Share on other sites More sharing options...
JFDIY Posted January 23, 2021 Share Posted January 23, 2021 Excellent, does this still involve the remote sensor to the rear of the backbox, or using the internal one built into the thermostat faceplate? Link to comment Share on other sites More sharing options...
Ultima357 Posted January 23, 2021 Author Share Posted January 23, 2021 2 hours ago, JFDIY said: Excellent, does this still involve the remote sensor to the rear of the backbox, or using the internal one built into the thermostat faceplate? I've put in a remote one as a test, but both this and the inbuilt one read equally well now. My back boxes are metal but it clearly shows the problem of the heat generated by the psu. Yes, the battery wireless operated ones don't have this issue but they do have the flaw of the battery. A couple of years ago we went on holiday for a few weeks (when I had such a system in the old house) in the autumn and in the last week on our hols, the battery died. So instead of coming home to a nice warmed house, we arrived to a cold one. Not good! Will be speaking to the Heatmiser developer next week. Link to comment Share on other sites More sharing options...
Ultima357 Posted January 23, 2021 Author Share Posted January 23, 2021 As I read today. "It's relatively easy in physics to measure something. The hard part is knowing how accurately you are measuring it" Just about sums this saga up. Will buy some more spacers and get on with retrofitting them to the other stats now. They're just 97p each from Screwfix if you buy 3 plus. Search for single gang spacer. 1 Link to comment Share on other sites More sharing options...
MJNewton Posted January 23, 2021 Share Posted January 23, 2021 13 minutes ago, Ultima357 said: Yes, the battery wireless operated ones don't have this issue but they do have the flaw of the battery. The best of both worlds is just to have a remote PSU. Thats what the ones with hubs do (the hub is the PSU) whilst others have a PSU local to the stat (but not inside). Some (eg Nest) allow either. Link to comment Share on other sites More sharing options...
ProDave Posted January 24, 2021 Share Posted January 24, 2021 10 hours ago, MJNewton said: The best of both worlds is just to have a remote PSU. Thats what the ones with hubs do (the hub is the PSU) whilst others have a PSU local to the stat (but not inside). Some (eg Nest) allow either. You are assuming that it is the PSU generating the heat, not the complicated CPU chip. Link to comment Share on other sites More sharing options...
MJNewton Posted January 24, 2021 Share Posted January 24, 2021 (edited) 10 minutes ago, ProDave said: You are assuming that it is the PSU generating the heat, not the complicated CPU chip. True, but they all have CPUs and some likely more in number/power than what the Heatmiser has (eg those with fancier displays, occupancy sensing etc) and yet don't suffer these issues. Agreed it's speculation though. Edited January 24, 2021 by MJNewton Link to comment Share on other sites More sharing options...
MJNewton Posted January 24, 2021 Share Posted January 24, 2021 (edited) You've got me thinking now @ProDave: a view through an IR camera would be interesting, and really help pinpoint the source(s) of the problem (and effectiveness of any attempted solution). Edited January 24, 2021 by MJNewton Link to comment Share on other sites More sharing options...
Ultima357 Posted January 24, 2021 Author Share Posted January 24, 2021 2 hours ago, MJNewton said: You've got me thinking now @ProDave: a view through an IR camera would be interesting, and really help pinpoint the source(s) of the problem (and effectiveness of any attempted solution). Definitely is the transformer. When you pull the back plate forward to fit my spacers, it's a nice warm handful. Guess around 30 to 32 deg. When I get the next spacers, I'll measure one. Decided to go with slots to the wall in the end, it doesn't seem to make any difference and is more pleasing aesthetically. 2 Link to comment Share on other sites More sharing options...
Onoff Posted January 24, 2021 Share Posted January 24, 2021 Would you consider angled slots so as not to accumulate dust? Saying that I imagine you have MVHR so not a worry? Link to comment Share on other sites More sharing options...
Ultima357 Posted January 24, 2021 Author Share Posted January 24, 2021 27 minutes ago, Onoff said: Would you consider angled slots so as not to accumulate dust? Saying that I imagine you have MVHR so not a worry? Probably not a worry as its vented to rear of the plate which is all sealed in any case. It would be more difficult machining it on my router table at an angle too. Easy enough as a straight vent, but delicate and careful approach needed. We do have MVHR but you still get dust. The man who invents something that does away with dust will become a very rich man?. Link to comment Share on other sites More sharing options...
MJNewton Posted January 24, 2021 Share Posted January 24, 2021 Looks alright that! Link to comment Share on other sites More sharing options...
Ultima357 Posted January 27, 2021 Author Share Posted January 27, 2021 (edited) Now done all 11 (3 had remote sensors so not affected), recalibrated them and I now have much more stable temperature control, so very pleased with the result. As previously said, I measured the temperate of the top slot probing into the back. 29 degrees! Have sent a new design to Heatmiser. Given the large cost of tooling, I wouldn't expect them to jump on it though. Of course the slots would be on three sides, I just showed them how it could be disguised. Edited January 27, 2021 by Ultima357 4 Link to comment Share on other sites More sharing options...
pudding Posted January 10, 2023 Share Posted January 10, 2023 (edited) Just to bump this topic back up as it seems most relevant to my issues. I've had 8 x V1 neostats installed for about 8 years now. About 3 months ago, 2 of them failed. The front part of the stat was fine, it was the rear backplate which had failed, I bought another 2 V2 stats, just used the backplates from them and put the V1 front plates back on in order to keep all of the room details/wifi bits. From reading this thread jut now I'm guessing it was the PSU that had failed. Then, this week yet another stat has failed, same thing! So after discovering this thread I'm guessing this issue with heat build up from the PSU (I calibrated my stats with the offset but never went as far as drilling extra vent holes etc), will eventually lead to failure of all of the stats? Or have I just been really unlucky? I emailed Heatmiser telling them of this 3rd stat failing withing a few months of each other and asked about possible solutions and if I should expect all my V1 stats to now fail, and simply got this reply - 'Hi xxxx, Although we understand your frustration your neostats have been powered up 24 hours a day for almost 8 years. Regards, xxxx' Obviously I'm pretty reluctant to keep buying more neostats if they're just going to fail again in a few years time and pretty pee'd off with the fob off dismissive email reply. Has anyone else had any complete PSU failures like me? Any alternatives, or should the V2's i'd now be buying as replacement be any better? Edited January 10, 2023 by pudding Link to comment Share on other sites More sharing options...
ProDave Posted January 10, 2023 Share Posted January 10, 2023 Care to take the cover off one of the failed back plates . psu's and post some photos. I have just fitted 8 of these to the local village hall. Looks like I need to schedule replacing them again in 10 to 11 years...... 1 Link to comment Share on other sites More sharing options...
Temp Posted January 10, 2023 Share Posted January 10, 2023 Are there any electrolytic capacitors in there? Any with bulging tops? I would try replacing them with a good quality high temperature replacement. Link to comment Share on other sites More sharing options...
ProDave Posted January 10, 2023 Share Posted January 10, 2023 The time to replace them is before the PSU dies completely, there may be more wrong with it now. Link to comment Share on other sites More sharing options...
pudding Posted January 10, 2023 Share Posted January 10, 2023 (edited) I'll try and take one apart tomorrow when I'm back home from work and see if there's any obvious signs of bulging caps etc and post some pics. In the meantime, cheapest source of new ones would be good? Best ive found so far is £59.99 atm. Edited January 10, 2023 by pudding Link to comment Share on other sites More sharing options...
MJNewton Posted January 10, 2023 Share Posted January 10, 2023 (edited) I wonder if it'd be worth exploring the possibility of substituting a different PSU inside the backbox? I can't imagine it is anything exotic, and not only might it give greater longevity but it might also improve performance of the thermostat noting the excessive heat that the original appears to give off. Edit: I see this suggestion is just a repeat (or variation at least) of what I mentioned a couple of years ago so apologies for that. I did wonder why I'd received notification of this thread updating as I didn't recall being previously involved! Edited January 10, 2023 by MJNewton Link to comment Share on other sites More sharing options...
pudding Posted January 10, 2023 Share Posted January 10, 2023 Would it be worth pestering and chasing up Heatmiser further for anything? From their initial response to me and others interactions, I'm not sure they'd be too willing to offer much/anything at all? Link to comment Share on other sites More sharing options...
pudding Posted January 12, 2023 Share Posted January 12, 2023 (edited) So I've got around to swapping over the power supply/backplate on the broken neostat, and as suspected the front section was fine and working as soon as it plugged back on. Here's pics of it all:- New backplate at the top with vents to aid heat dissipation, bottom is just solid plastic. Old plastic casing with PSU board removed Pics of the old broken PCB: So based on these I couldnt really see anything obviously wrong, no bulging caps or burn marks anywhere. But, based on the fact the new psu/backplate has the vents and the old one doesnt, surely that is an admission of the fact the old casing was leading the heat build up and eventual failure? Ideally I want all of my old neostats replaced with these new ones, free of charge of course! How best to go back to Heatmiser after their fob off email? Or just suck it up, 8years use is a long time and just buy new ones and replace as they fail? Edited January 12, 2023 by pudding Link to comment Share on other sites More sharing options...
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