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Where to put wall thermostat?

Discussion in 'Plumbing and Central Heating' started by ericmark, 17 Apr 2017.

  1. ericmark

    ericmark

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    At the moment the wall thermostat is in the hall, I however have a problem, the hall has no TRV and has to be crossed to enter the wet room, if set to 20°C hall is great, but rest of house too hot, open the lock shield valve and hall hot and rest of house cold, no amount of fiddling seems to get a balance. Not surprising as needs to have a threshold free front door so there is a cold draft with wind coming from front of house, no real cure due to wheel chair access. So best option would seem to be fit a TRV to the hall radiator. That is all well and good, but then where can I put the wall thermostat?

    As far as I can work out the wall thermostat is to stop the central heating boiler running in the summer, it should not do a thing in the winter, in the winter the TRV controls the room temperatures by adjusting the flow, this in turn controls the return water temperature as the bi-pass valve starts to open and the return water temperature controls the boiler flame height, so we have analogue control with low hysteresis, if the wall mounted thermostat controls the boiler then we get a high hysteresis so only when we reach the point where the boiler can't turn down low enough so has to switch on and off should we be looking at the wall thermostat taking over control.

    The anti-cycle software in the boiler can't cope in heart of summer, so then we want the wall thermostat to take over, with standard TRV's it should be just a case of setting the wall thermostat slightly higher than the TRV, however this does not work, as set to 21°C the central heating would turn off too late in the summer and house would end up far too hot.

    However heat raises and in the landing and bedrooms the temperature reaches 21°C far earlier, it would seem having the thermostat upstairs on the landing would remove the problems of cold drafts from front door, and it could be set to 20°C with TRV set to 18°C and in theory it should work?

    So why is not every house set up that way? What have I missed? I can't believe I am the only one to consider the wall thermostat should be placed upstairs away from drafts. I look at the places it can be placed, or more to point where it can't be placed, no good in living room as eTRV fitted. Same will apply for downstairs bedroom and hall, kitchen heat from cooking will upset it, wet room underfloor heating will upset it, this only leaves upstairs, bedrooms will be set too warm, loo has no radiator, bathroom again set on hot side, so it would seem only place is the landing. So what if anything have I overlooked?
     
  2. stem

    stem

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    Generally, the room thermostat should be in the coolest room. ie the last to heat up, so that the other rooms have reached their temperature first before the room thermostat turns off the entire system.
    That is exactly as it should be. Having two devices trying to achieve the same thing in the same room does not work. Consider if the TRV in the hall closed down the radiator before the temperature set on the room thermostat was reached. The radiator would cool and during the heating season, the room thermostat would never turn off, it would be permanently on. On the other hand if the room thermostat was set lower than the TRV then the TRV would never operate, so what would be the point in having it? Thermostat Rule 1 there should be at least one radiator without a TRV in the room where the room thermostat is located.
    Then you have the ideal solution! If the hall temperature is "great" simply set the TRV's in the rest of the house lower, then those rooms won't be too hot.
    No! not at all. It is there as a 'boiler interlock' to shut the boiler down when the property is up to the required temperature come summer, winter, autumn or spring. If a system is just equipped with standard TRV's and without a room thermostat, then whilst the radiators will cool, the boiler will keep going just to keep itself warm and wasting energy. With a properly designed system, the room thermostat should be shutting the boiler down from time to time even when it's the middle of winter. In the spring & autumn it will be much more, I estimate mine is only on for 10% (or less) of the time at the moment. During the summer most people turn their heating off completely anyway.
    I have come across installations like this twice. In both cases it was when I had been asked to relocate the thermostat because it wasn't working. What happened was that when the thermostat was located upstairs and turned the entire heating system off, because heat rises it didn't cool fast enough where the thermostat was located to turn the heating back on, meanwhile, downstairs the temperature was falling and it was getting chilly.
    In this case the TRV would switch off the radiator at 18°C, so the temperature will not reach 20 and the room thermostat will not turn off.
    You aren't. Rule 2 is that thermostats should be placed away from drafts. Also consider:

    3. Do not locate the thermostat in a room where it will be subject to other heat sources such as cooking appliances, used fireplaces, or sunlight. Any extra heat that warms up the room where the thermostat is located, will switch off the thermostat, and all of the radiators in the rest of the property.

    4. Do not locate the thermostat above or close to a radiator.

    5. It should be located in an open space to allow air to circulate freely around it so that it senses the true ambient temperature of the room in which it is located, not stuck in a corner, behind curtains or furniture. Most manufacturers recommend 1.5 metres above the floor.

    You could always install a wireless thermostat, and then you could easily try it in the different locations to see which works best. Don't forget to remove the TRV head, (or at least set it to its maximum setting) in the room where you are trying the room thermostat though.
     
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  3. ericmark

    ericmark

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    Now before getting eTRV's I got a wireless free standing thermostat, it did work for a time, then started missing temperature changes and would over or under heat the room. However before it went wrong, moving it around, I actually found best location was near to the radiator, of course it had to be set a little on the high side to compensate for heat from radiator, but near radiator the hysteresis was far less, hence why went it went wrong I went for eTRV's instead.

    Main point with eTRV is although it is set wirelessly, the info is retained local, so even with hub unplugged it still works, unlike the wireless thermostat.

    Still getting my head around the TRV, it does seem they are approximate rather than like the eTRV accurate to within a degree or so, but hall has been a pain in my side, wind direction will alter it so much, trying to set the lock shield valve so rest of house works OK has just not worked.

    So finally fitted a TRV to the hall radiator, easy enough to remove again just swap head for the cap and it is a simple valve, but adjusting the lock shield did not work as it also effected the amount of water getting to the other radiators, with a TRV once it closes then there is more water else where.

    But last night was total failure, 6:30 timer switched the central heating off, so at 7:10 when it switched back on again the boiler would run, however moving from 15°C to 19°C before the two rooms with eTRV's hit the new temperature the thermostat in the hall set at 17°C switched off the boiler. By 10:30 am rooms had still not warmed up, in the end reset thermostat to 18°C at which point it worked, latter reduced it back to 17.5°C and the thermometer sitting on the thermostat is showing 17.8 and boiler still cycling on and off and all rooms up to temperature.

    So now it's wait until tomorrow, the boiler off time has been increased, the hall lock shield closed a little, the TRV in hall at 2.5 and thermostat at 17.5°C the overnight temperature in the two rooms with the eTRV's set at 17°C and set to move to 19°C a bit earlier to give it a chance.

    I have 3 days to get it right before mother returns. To hot at night and she wakes up, but under 19°C in the day she complains its too cold. Going to bed 9 pm and getting up at 8 am using just the timer the room gets too cold, it needs some heat over night, with rooms set to 15°C this was too much for the eTRV to heat it back up again, so trying at 17°C which I hope is cool enough not to wake her.

    It's easy for us, we simply move the blankets or sheets at night, but she will get out of bed and wake up whole family so it has to be right. While writing this although set at 17.5°C the hall temperature has climbed to 18.2°C and boiler I can hear is still cycling on and off. I am just starting to wonder if this wireless thermostat has also gone up the creak?
     
  4. stem

    stem

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    So suddenly they are eTRV's.......no mention of this in your original post, or did I miss it! :rolleyes:

    If they provide a boiler interlock, then you don't need a room thermostat.
     
  5. ericmark

    ericmark

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    However much I want to jump in and alter things yet again, I realise I have now reached the point where I need to wait and see how it works. At the moment I don't have boiler interlock, the eTRV's are ITTT and are designed to work with Nest.

    So I suppose the next step is install Nest?
     
  6. Move the thermostat into the living room, set the eTrv to 30deg so it never works, and at some stage fir a trv to the passage rad.

    A hallway that has a door that opens to the outside will always be the worst room for a thermostat, and therefore throw the whole house out of sync. You have an eTrv fitted in the living room, but are they everywhere, is which case you should have a controller somewhere.

    but whether you have eTrvs everywhere, or just in the living room, your main problem, is that you are relying on the trvs to regulate the temperature of each room, but it's obvious that the rads have never been balanced to bring them all up to the required temp at roughly the same time. You need to set the lockshields to about half a turn open, and then over a few days, you check to see how the rooms come up to heat. Some rads will be slightly larger than required, and so heat the room up quicker, so you turn the lock shields down a fraction of a turn each time. The rads furthest away will require the lock shields to be opened up more. After the rads have been balanced, the eTrvs will then take over and regulate the rooms as say the sun moves round the house, and warms the rooms up differently.
     
  7. ericmark

    ericmark

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    The central heating was fitted by a load of cowboys, this was plain when I first visited after it was fitted to find a power shower plumbed to a combi boiler which was illegal. I got that put right, but it was an indicator as to their skill.

    Moving on the problem now seems to be doors open or doors closed. It makes a huge difference to boiler running if kitchen to hall, wet room to hall, or any of the other rooms connecting to hall have the doors left open.

    I am hoping now I have a TRV on the hall radiator this will compensate to some extent to doors being left open. As least the hall temperature now seems to remain static at 18.3°C, but having rooms at different temperatures leaving a door open must cause problems.
     
    Last edited: 20 Apr 2017
  8. Right, can you give us a breakdown of your setup. which rooms have etrvs, which (if any) have trvs, and which thermostat do you have. I think part of the problem lies in having a thermostat and the eTrvs, as they are conflicting with each other. Obviously, the rads with the etrvs won't work if the thermostat has switched off the boiler, so I think you need to get someone qualfied in to sort out the problem. For now, it may be best to set the eTrvs to 30deg, so they don't operate, and balance the rads as I've suggested, then get someone qualified in to try and integrate everything.
     
  9. ericmark

    ericmark

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    Downstairs four rooms, living room eTRV fitted, bed room eTRV fitted, hall TRV fitted, kitchen towel rail no TRV, wet room towel rail plus electric UFH thermostat on UFH but not TRV underfloor heating used twice a week when mother having a shower.

    Upstairs three bed rooms all with TRV, landing also with TRV, loo no heating, bathroom with TRV, airing cupboard with no TRV fitted. Upstairs works fine no real problems.

    Also in the hall a wireless thermostat fitted, and in kitchen a programmer fitted, there is also a wireless programmable thermostat in living room set to frost so not used, it is I think faulty and losses coms that's why set at frost and never used.

    So two days, yesterday and today, yesterday the two eTRV's were set at 15°C overnight, in the morning when it went back to 19°C the rooms failed to heat up, the hall was set at 17°C so today the eTRV's were set to 17°C and the hall at 17.5°C the hall the thermometer fell off onto floor so not 100% on hall temperature but it had been stable at 18.2°C all the time it was stuck to the thermostat so likely stayed at that, it also returned to 18.2°C once stuck back, and the two eTRV's stayed at current 19°C. It is just as if the eTRV's did not change temperature at 22:30 living room and 20:00 bedroom as programmed but stayed at 19°C although software showed target as 17°C.

    As to a professional sorting it, well a so called professional firm installed the system with a power shower connected to mains supply, sorry to me not very professional they clearly lacked a warranty of skill, not a one man band, they had a rather large operation going on with all the people having qualifications to say they knew what they were doing, members of at that time Corgi, gas safe did not exist then, and no cross over of work, the heating engineer would not power up boiler without the electrician saying go. The foreman was called over the power shower, and admitted it was illegal and agreed to change it for a standard thermostatic shower, so whole job was checked over after completion. Yet not a single lock shield valve was moved from fully open. So seen so called professional and no thanks, I need to sort this myself.

    The fact that the eTRV controlled rooms stayed at the same temperature when target set at 17°C and when set at 19°C points to the valves being faulty, or more likely the hub, as both valves acted the same. I thought the info as to what temperature and when to change was stored in the valve, but now wonder if stored in the hub? In the bedroom there is a baby alarm, which has shown 21°C night and day, so can confirm that room did not alter one degree between night and day settings, and the living room has a camera which shows 17°C it is on the window sill so expect it to show low, and that shows that room has not altered night and day.

    As a result of the temperature remaining static night and day, it would seem what ever is wrong is not due to how the radiators are set, it is down to faulty equipment some where, since also had problems with the wireless programmable thermostat, it seems likely some local interference is upsetting wireless devices. Yesterday I came across my wave meter, I know an oscilloscope would be better, but think it's down to RF interference. It says "Radio Frequency: 433MHz Band" the Seventy Centimetre (70cm) band within the UK is 10MHz wide commencing at 430MHz and extending through to 440MHz. So I actually have a transceiver which runs on the same band as the eTRV's however it needs new batteries, so I think getting my transceiver working is the first thing to do. I looked at the instructions for the Horsmann HRFS-1 RF thermostat and no frequency given also the Honeywell Y6630D uses DECT which was developed by ETSI but has since been adopted by many countries all over the World. The original DECT frequency band (1880 MHz1900 MHz) is used in all countries in Europe. Outside Europe, it is used in most of Asia, Australia and South America. Now my door bell also used DECT as do my cordless phones however it also says frequency 868.3 Mhz my radio may receive on this, but not transmit. I may be able to find a ham with 23 cm radio but these are too high of a frequency. Why the Horsmann HRFS-1 does not give the frequency I don't know, I can only assume it's cheap tat?
     
  10. stem

    stem

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    That is exactly why the room thermostat should be located there. It should be located in the coolest place, the place that needs to have the heating on longest. Remember the room thermostat turns off all of the radiators, (unless you have separate upstairs / downstairs zones) not just the radiator in the room in which it is located.

    When the room thermostat is in the coolest place, it will make sure that heat is available to all the rooms in case they need it. If heat is not required in the other rooms, their TRV's will then turn off the radiators, so the room is not overheated.

    Putting the room thermostat in a location that is warmer than another rooms, and where it is up to temperature more quickly will turn off the whole heating system meaning any cooler rooms that still need heat, won't get it.
     
  11. Agile

    Agile

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    There is a lot of information in this thread!

    Doggit seemed to have concluded that the system is not properly balanced and asked you to set the lockshields to be open only 1/2 turn which is a rough setting used by better installers as in most cases it can be left there.

    You also gave another clue in an early post when you said altering the hall rad affected all the others, another clue that the system is not balanced.

    In your last post you say the installers left all the lockshields fully open. Not a good sign of professionals.

    But you have not told us what, if anything, you have done to try to effect a balance.

    My conclusion, based on what you have said, is that it badly needs proper balancing. The 1/2 turn lockshield setting will go a long way towards dealing with this!

    Tony

    G8ABQ
     
  12. ericmark

    ericmark

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    I have turned each radiator off on the lock shield valve, then with hand on pipe little bit at a time turned them back on until I could feel hot water flowing, I know I should put two thermometers one on feed other on return, but step one has to be fit the cap on the TRV instead of head to ensure fully open, unfortunately non of the caps were left by the installers, so all I could do was set TRV to maximum temperature.

    However Tony as a G8 you may be able to suggest how to check for interference. Fact that each day seems to have different results points to something causing interference. I have some stuff around, but although I have renewed licence each 5 years, I am no longer active except for odd RAYNET event, and I found my FT50R will not turn on, so at moment only 2 meter stuff.

    As said from last two days very little changed with settings, but massive change in results, it does not make sense that such a small change should result in such a big difference, moved the temperature setting 0.5°C on the wall thermostat, and moved night time temperature from 15°C to 17°C on night one the temperature dropped to around 16°C both rooms, and in morning failed to raise to 19°C even after 5 hours. Day two thermostat set 0.5°C higher at 17.5°C and the two eTRV's set to 17°C over night rather than 15°C and the temperature in both rooms remained at 19°C as if the eTRV had not changed to over night setting.

    It to me looks like something is blocking signals to valves what do you think.

    Eric
    GW7MGW, VP8BKM, VR2ZEP
     
  13. Tony to the rescue,aint he a diamond geezer.
     
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  14. ericmark

    ericmark

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    I have been reading this website it talks about the Power line adaptors and the interference they cause, I think my easy way out is to invite a fellow radio ham with a working 70 cm radio to my house for a drink, and see if he can detect any signals on the frequency used. Although it would be nice to get the FT50R working again.

    But I have not really used my licence in years, started as VP8XBHZ, then got a full HF licence VP8BKM returned to UK asked for a reciprocal licence and was told you must be joking, so took RAE and got my GW7MGW licence, Hong Kong was better they used the same exam so just showed the paperwork from UK and got VR2ZEP call sign, however I was into packet radio, and as internet arrived so packet radio faded out, so all the gear was put in a ruck sack and got out only when RAYNET needed it. Now RAYNET have one event a year, so even that has gone. I have no aerials on the house only worked mobile so really not cued up on what we have today.

    I knew a few G8 and two letter call sign holders and they were very clued up, however the three letter call signs were same as me, VHF and above, until Morse was no longer required. However he must have a good few years more than me, so I hope the old man can help?
     
  15. Agile

    Agile

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    I dont think that I can help much directly on the RF interference aspect but can point you to a couple of possible helps.

    First is an App if you have a smart phone which gives a spectrum analysis display of all the WiFi channels. You have to search for it and something like WiFI display or analysis might find one, there are several.

    Next there are several cheap ebay digital frequency meters for only about £2-3 but you have to wait for them to arrive by China Post.

    It makes me wonder if you just have too many RF devices around and they are interfering with each other.

    Next is to ensure they are all within their operating range. I have a customer who has a Nest which only communicates with the boiler unit when it is in the same room. His study seems to be a Faraday cage and will not receive any mobile sigs at all.

    You tell us so much information that I find it all rather difficult to assimilate. But you seem to be wanting to use your controls together in a configuration not expected.

    The whole purpose of the wireless TRVs is to bring on the boiler if any of them call for heat. But you don't seem to have any receiver for them to do that.

    But if the lockshields are not too far open then any one rad coming on or off should not significantly affect any others.

    Tony
     
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