Doors open / closed and effects on heating.

Discussion in 'Eco Talk' started by MGW, Jan 13, 2020.

  1. MGW

    MGW Screwfix Select

    I will guess I am not alone in having a thermostat in the hall around dead centre of the house and no radiator close to it, and with doors open it gets heat from radiators in living room, toilet, kitchen, dinning room and hall so is a reasonable average of the homes heat.

    The TRV will control each room so no room gets too hot, however the TRV will not turn on the wall thermostat, and being centre of house it is the last place to cool on entrance level, only the toilet does not have a door to outside, and only dinning room does not have alternative heating.

    So to save energy all but the toilet TRV have electronic programmable TRV heads, so the dinning room for example is set to eco 17°C until 5 pm when it moves to 20°C until 9 pm when we will have finished evening meal so returns to 17°C. Every room has it's own schedule set to match how we use the room.

    There are ways to get rooms warm on time, turning the wall thermostat down to 20°C from 20.5°C at 4 pm and back to 20.5°C at 5 pm ensures boiler fires when the dinning room TRV changes temperature. So far so good.

    However with every room set to different schedule the doors being open or closed may be causing a problem. What I know is we have an over shoot problem, what I don't know is how to stop it, or what is causing it. The wall thermostat is mid way between 4 doors, and 2 doors away from hall radiator, at night I close all doors, and in the morning the TRV in hall moves from Eco 17°C to comfort 19°C it always shows around 2°C lower than wall thermostat, so I have tried to allow for that, also allowing for time for warm are to reach the wall thermostat that moves from 17°C to 19°C then another 0.5°C per hour until at 20.5°C so ensuring boiler cycles off/on for 4 hours allowing other rooms to reach the comfort setting.

    As to how well it works depends on wind direction, how much sun, and temperature outside, living room does catch the sun when it shines.

    But once we get up, then we tend to chock open the living room door, and other two doors not on rising butt hinges so they will stay where put, so often kitchen door also open allowing cups of coffee to be carried using both hands. So at night doors closed, in the day when fire safety is not such an issue as not sleeping two doors are left open.

    Now the wall thermostat is claimed to learn (Nest gen 3) but can't see how it can learn when so much changes, it does not know if door is open or closed. So in the evening we tend to feel cold, maybe because heat from dinning room as turned off the wall thermostat, maybe simply over shot, living room at this time target 19°C but the TRV heads report 17°C and 20°C for the two radiators, (2:30 pm) I am trying setting the hot side of room higher, assuming heat not leaving the radiator due to furniture. With 2°C between target and current the TRV should be wide open, so no point changing that one.

    Up stairs the rooms seem spot on, using eQ-3 TRV heads up stairs, they only show target, but clearly heat raises, so expect up stairs to stay warm. Kitchen down stairs eQ-3 as has open window function so turns off radiator when unloading car, rest all MiHome Energenie and all new TRV bases.

    Oil fired boiler so cycles off/on does not modulate, used the MiHome Energenie in last house but that was gas fired so modulating boiler, but have to say the TRV heads were spot on, every room (only used 3 rooms) was very close to target, if we got morning sun the living room could over shoot, but radiators were cold so the TRV could not be blamed for that, purely down to sun.

    So tried tweaking balance with lock shield, and setting steps with wall thermostat, so now looking at the doors, as a kid was always being told cau'r drws (Welsh for shut door) from mother, and put wood in hole from father, so brought up to close doors, but this was before central heating with multi zones, the idea of having 8 areas all with their own schedule of heating was un-thought of when I was a kid in the 50's, we had open fires and high backed chairs to reduce the draft.

    Also today no need to re-invent the wheel, I am sure others have had the same control problems, my idea was Nest Gen 3 should link to MiHome Energenie however the support has it seems been withdrawn when Google took over, and the TRV followed the wall thermostat which does seem wrong way around, plus as said there is no temperature offset function and the TRV is up to 3°C colder than wall thermostat, (it is lower down and closer to front door) so the follow command would not work anyway.

    Maybe just expecting too much?
  2. The Teach

    The Teach Screwfix Select

    With the fuel and controls mentioned,your living in mgw cuckooland (again). Maybe invent a system that fit's a temp sensor chip in human beings so they are comfortably warmed every second around their drum and other places.

    Funnily enough,this morning went to view a new development. The heating/water is all electric which is good !

    The heating/hw control can be manual or just wait. Geofenced so the occupiers whilst in the property or on there travel home their heating/hw appliances will heat automatically via phone/tablet or the developers own gadget.

    Tbh,saving electric is a good idea we buy and sell electric often there is a spike in electric demand when kiab makes a cuppa during the adverts of coronation street . Mains natural gas is on its way out,its not a secret ;)
    BikerChris and MGW like this.
  3. Hans_25

    Hans_25 Screwfix Select

    I have the Drayton Wiser setup with iTRVs and have the same issues - mainly overshooting but also the TRV temps being about 2 to 3 degrees higher than actual. Its a right ball ache trying to get everything to work, have considered replacing the TRV with their manual counterparts!

    I think the main issue is that iTRVs are kinda "digital" whereas manual TRVs are more "analogue". iTRVs are on/off whereas manual TRVs can open/close gradually as the temperature varies.
    MGW likes this.
  4. MGW

    MGW Screwfix Select

    Goefencing and occupancy detection make the over shoot worse, often on a Wednesday only day I regularly go out all day, heating really over shoots on return.

    I think my TRV heads are analogue not digital they slowly open and close, I suspect designed for gas boilers, so by controlling flow through radiators it in turn controls return water temperature which in turn causes the boiler to modulate. However since using oil, and oil does not modulate, maybe that is the problem, they may be opening wider and wider as room cools, then can't shut fast enough when the boiler fires up and hot water is circulated?

    However if the wall thermostat is calling for heat, water is circulated, does not matter if boiler running or not, so I would expect it works similar to gas, boiler may use mark/space not modulation, but end result is the same, or is it?

    I had fans in first two houses to circulate the air, hot air heating in first, and Myson fan assisted in the second this forced air movement I suspect reduced the hysteresis.
  5. rk_diy

    rk_diy Member

    The new generation thermostats are advertised as "smart" but as far as I can see they "can not" be smart enough as they do not have enough sensors and inputs to "see and decide".
    Measuring the temperature of a space from a single point is not an accurate method to get an ambient average temperature. Particularly with TRVs, its worst place to take a reading just by the valve location. In modern houses with more open spaces (and open doors) conventional heating systems are having problems to provide comfortable and efficient zones. For a better approach to heating system, In my opinion, just temperature control by thermostats seems not enough but needs some sort of "air movement control" with forced air vents and more sensors around the house as well (instead of more thermostats) for an efficient and comfortable hybrid heating system.
  6. MGW

    MGW Screwfix Select

    In mothers old house I had a thermostat which could be moved, idea was she only used two rooms, so if the TRV stopped over heating, moving the thermostat into the room used should ensure that room was spot on, it failed mainly because the wireless thermostat range kept reducing think the frequency drifted.

    However before it failed I was able to test it in many locations, and the best was on a tea trolley in front of the radiator set a little high to compensate for being so close. It was then I realised under the radiator is likely best location. circulation.jpg We look at the diagram and realise this shows under the radiator it is measuring the return air temperature, as thermals will circulate the air, so actually on side of radiator is very close to perfect and with twin sensors one for air and one for water as with the Energenie MiHome electronic head on the supply side of course, with a standard room the TRV can do a very reasonable job.

    But in the hall this does not work, the shape of the area including stair means the chimney effect stops circulation, and not sure any fan would help either unless blowing air from landing back down to hall. So yes agree a heat recovery unit that moves air would seem the answer, however ducts around the house really need fitting as house is built, retro fitting a hot air system is not really an option.

    I suppose with a modulating boiler all the thermostat on the wall does is stop is cycling in the summer, the boiler is controlled by return water so the TRV's do all the work, and all the wall thermostat does is switch off the boiler as summer arrives. However this assumes we want the house at a set temperature day and night 24/7 which in the main we don't, when walking around the house the temperature can be cooler than when watch TV, and when in bed can be cooler still, and when I leave the house the temperature can drop to a easy recovery level so it does not take so long to re-heat on return.

    So 4 temperatures, stand-by when not home say 16°C over night in rooms being used 18°C during the day entrance level 19.5°C and evening 20.5°C and it is this changing temperature which varies for each room which causes the problem. Hive seem to have an answer, "Heat on demand" allows the TRV heat to tell the wall thermostat to fire up boiler when the room is under set temperature. Also EvoHome and Tado do some thing similar, however I have Nest, which does not have this option, and to be fair when I bought the Energenie MiHome electronic heads and started the system neither did Hive, the Hive TRV was only released in 2019.

    So I need to make what I have work as well as I can make it work. All house heating.jpg the layout is not good, red are radiators, orange is wall thermostat, so the thermostat is likely in the best location for a single thermostat for all rooms, but there is a time delay between rooms getting warm, and thermostat reading the increase in temperature, it is some where near an average of all rooms with internal doors open, but since all rooms not on the same schedule that does not help much either, I was so sure with mothers house I had it sorted with moveable thermostat, but proved wrong, and programmable TRV's worked far better, so I am first to admit I can get it all wrong. I read the books saying don't fit a TRV in room with wall thermostat, mothers house proved that was wrong, it was only after fitting a TRV in the hall I got it working well. But her house was gas modulating boiler, this house oil mark/space regulated boiler.

    As if I set one temperature 24/7 this house will work, it is the varying temperatures which cause the problem. So trying to get head around doors open or closed. In spite of fire risk, if leaving doors open means no over shoot then so be it. And as you rightly say there is no door sensor on thermostat, so if always left open maybe it can learn?

    But I am sure I am not first and will not be the last to use programmable TRV heads and have this problem, so worth talking about is to see what others have found.
  7. Jimbo

    Jimbo Screwfix Select

    The Wise system starts following a TPI type approach where off periods are introduced once within 1*C of the set point. The system is suppose to adapt to the heat and cooling rates based on it's (approximate) knowledge of outdoor temperature and observed rise and fall.

    Maybe the radiators are simply too powerful (lower flow temperature could help) or have high thermal mass (cast iron school style)?
  8. MGW

    MGW Screwfix Select

    The Nest thermostat is similar to Wise system as connected to my oil boiler, it should work out how long it needs to fire for to get to target temperature, the problem is where the thermostat is in relation to radiator, the time taken varies due to if doors open or closed, knowing why it over shoots however is not helping stopping it over shooting, leave doors open and the whole idea off zone control goes out the door, close doors and in fullness of time it will work, but one day doors open, and next day doors closed and it can't adjust to house.

    When we bought the house there was no thermostat, and the programmer had option of off, once or twice a day, and on. It seems only control was the TRV heads and walking outside and down a set of steps into the granny flat and plug in or unplug the central heating pump. This was independent to programmer, there was also a second pump controlled by a thermostat in granny flat, using this would cause reverse flow in main house radiators, and using house pump caused reverse flow in flat radiators. However the cables did got from programmer to wall in hall with insulation tape on the end.

    My aim of post is maybe some one else has the same problem, and maybe found a way around it? I think some where I have a setting wrong, rather than needing new equipment. I expect I am doing some thing silly.
  9. MGW

    MGW Screwfix Select

    Think I have found the problem, was up when heating started, hall radiator was only warm but other radiators hot, the hall radiator does get hot, but was not getting hot fast enough, seems some one (likely plumber) had turned the lock shield valve nearly off. It was in plumbers remit to balance all radiators, but I thought he had not bothered and they were as before he arrived.
  10. greenback78

    greenback78 Active Member

    I have a Tado that’s been in place for a few months now. I have smart TRVs in the main living areas and normal TRVs in the bedrooms upstairs (20 year old house so no separate zoning). The Tado also has a humidity sensor that senses when the level changes with temperature to sense if a window is open, which is very useful. It also offers different options on the geofencing to balance quick heating vs. Economy as you are coming home. Cost about £275 for the whole kit but my energy bills were around 15% lower in December than the previous year. The system seems a bit more straightforward than Nest, which was a deciding factor.

    Like you, the non TRV radiator in our hallway is key to getting the heating just right although we were lucky to have a well balanced system in the first place.
  11. MGW

    MGW Screwfix Select

    My hall radiator does have a TRV fitted, idea was 4 entrance level radiators would have energenie TRV heads linked to Nest, but when Google took over Nest the support for energenie was dropped, suspect soon Nest will do their own TRV heads? Think problem was plumber, he had turned down the lock shield valve, which I have previously carefully set, so I had not realised he had adjusted it, so was looking for some other item that was messing up the heating.

    Don't think even if Nest had not withdrawn support it would have worked, as TRV is always around 2 degrees colder that wall thermostat, having realised that, the two are set with a 1.5 degree difference between the two.

    I had suspected I had missed some thing silly, and I had, but house new to me, so was not sure how it should work.
  12. The Teach

    The Teach Screwfix Select

    Think your expecting to much from the central heating system,fitting gadgets is not necessary. The users need to interact with the various thermostats and adjust them on a regular basis to maintain their comfort conditions.

    Its how wet central heating has been for many years,different users have different heat requirements. Some rooms leak heat more than others,some systems are incorrectly installed.

    Manual user intervention is the original smart system :D for comfort & fuel saving.
    MGW likes this.
  13. MGW

    MGW Screwfix Select

    I must agree the "The Teach" there is nothing wrong with manual control, that is what I had as a child, learnt how to knot sheets of newspaper to light the sticks, which lit the coal, which lit the coke, and how to push the damper in or pull the damper out to control how much heat went into the domestic hot water, however out of personal preference I would like to wake up to a warm house and come home to a warm house.

    With my other house we have an open plan, and there is no real way to heat just selected areas, if living area is at 20 degs C so is the dinning area, and down stairs there are no TRV's fitted, all controlled by a central thermostat. Upstairs the TRV's stop bedrooms over heating, without the TRV leave door to bedroom open and bedroom gets too hot, leave it closed and it got too cold, the TRV compensated for door being open or closed. And only three small bedrooms, heating them or not heating them would make very little difference to heating bill.

    Mothers house up stairs was unused, mother was an amputee so could not get up stairs, so heavy curtain around bottom of stairs and only 2 rooms heated, however even with only two rooms, there was a problem due to doors and windows. With doors shut the morning sun through bay windows could even in winter heat room to 30 deg C, tried setting the TRV so when sun came out, radiator switched off, but *123456 on a TRV is as much use as chocolate fire guard, original central heating was only designed to warm house twice a day, first thing before getting up, and last thing to warm bedrooms, during the day it was coke fires.

    New central heating however was designed to replace coke fires, but unlike the coke fires there was very little individual control for each room, that was until the wax TRV was replaced with electronic type. Then the system worked, and when we came to live with mother to look after her, we added more electronic TRV heads, and they worked well.

    When we sold mothers house the old wax TRV heads were put back, and we brought the electronic heads to this house, so now 14 rooms, it does not make sense to heat them all, the granny flat (4 rooms) is set to frost control only, the toilet, shower, bathroom areas kept hot all the time, kitchen, dinning room, living room, bedroom 1, bedroom 2, craft room, office, and hall/landing all have individual heating controls both temperature and time, however the hall has the master thermostat, so that area controls boiler, as long as boiler fires up once every hour or two, the electronic TRV heads will control each area.

    So don't want hall temperature to change fast, taking down 1 degree at a time allows boiler to fire up and maintain other rooms, taking it up 0.5 degree at a time extends the heating time allowing all rooms to heat up when programmed, including dropping 0.5 and coming up again an hour latter to ensure boiler running when dinning room set to heat up. Not perfect but near enough, until that was when the hall started to over shoot. Now the fault has been found, all working again.

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