Nest in a bedroom

[Midwest]

In my property, I have an S Plan Plus CH system. The first floor zone is controlled via a low voltage programmable thermostat. The stat is made by Danfoss, and is quite frankly rubbish and needs replacing. The current position of the existing stat, is in the main bedroom which doesn’t have thermostatic rad valves. All the other first floor rooms have thermostatic valves.

I could just replace it with something similar from say Honeywell. However, I was thinking of installing a Nest thermostat.
Wife and I wake at different times for work, and retire at different times as well.

Not with standing the additional cost, would the Nest function properly in a bedroom?

 

[buzzlightyear]

Midwest the bedroom is it the coldest part of the building considering their is sat in there no sats on the rads.
Me if possable put rads sats on and move wall sats you could put the nest on the top landing .

 

[davesparks]

Yes the nest, or any thermostat will work fine in a bedroom, if the heating system is properly balanced.

The old idea of it must be in the coldest room is wrong. The thermostat should be in a room with a radiator which does not have a thermostatic valve on it, otherwise you'll hav etwo thermostats working against each other.
All other radiators should be balanced against the 'control' room so that every room heats up in line with that room.
Then is variations in temperature are required in each room they can be achieved by using the thermostatic valves on the radiators, but overall the system will heat up uniformly.
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Midwest the bedroom is it the coldest part of the building considering their is sat in there no sats on the rads.
Me if possable put rads sats on and move wall sats you could put the nest on the top landing .

The thermostat should not be in the coldest room, that will cause all of the other rooms to be overheated.

 

[Midwest]

Thanks chaps, I understand the concepts of stats & thermostatic rad valves.

I’m just wondering how the Nest will work with people movements in bedroom that won’t have much movement (at my age at any rate ).

 

[WallaceP]

Thanks chaps, I understand the concepts of stats & thermostatic rad valves.

I’m just wondering how the Nest will work with people movements in bedroom that won’t have much movement (at my age at any rate ).

It asks where the stat is fitted on set up, Im not sure if it changes anything on the program tho, or if its just there to whittle out some more information from you.

 

[EricMark]

Yes the nest, or any thermostat will work fine in a bedroom, if the heating system is properly balanced.

The old idea of it must be in the coldest room is wrong. The thermostat should be in a room with a radiator which does not have a thermostatic valve on it, otherwise you'll hav etwo thermostats working against each other.
All other radiators should be balanced against the 'control' room so that every room heats up in line with that room.
Then is variations in temperature are required in each room they can be achieved by using the thermostatic valves on the radiators, but overall the system will heat up uniformly.
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The thermostat should not be in the coldest room, that will cause all of the other rooms to be overheated.

It depends how the thermostat is used, there are two ways to use a thermostat, in my old open plan house the thermostat was near the arch between living and dinning room and it worked well, upstairs could over heat if doors left open to bedrooms, but use of TRV on bedroom radiators reduced this problem.

In this house the wall thermostat is in the hall, and in theory for it to work the hall TRV needs linking to the wall thermostat, however thermals in the hall don't carry the heat to the wall thermostat very well, so in real terms the TRV has to be set lower than the wall thermostat, not quite worked out why, but the wall thermostat always shows a higher temperature to the TRV.

At moment target 17°C current 16°C, but wall thermostat target 18°C and current 18.5°C so within the hall the temperature varies from 16°C to 18.5°C so to get the wall thermostat to turn on the boiler the TRV schedule needs to be set around 2°C lower on the TRV to the wall thermostat.

Big point is if using a programmable wall thermostat then the TRV also needs to be programmable.

But first look at how the boiler is controlled, with gas in the main the boiler can be modulated, that is turned down, so to stop the hysteresis (sine wave of temperature) everything is analogue, the TRV slowly closes as the room warms up, this causes the by-pass valve to slowly lift, and more and more non cooled water to return to the boiler, which in turn causes the boiler to reduce output, and the reverse as room cools.

However there is a problem, as the weather improves the boiler reaches minimum output, so at that point it has to cycle off/on. And as the weather improves further the boiler will continue to cycle all through the summer, so the way to stop the cycling is the wall thermostat, which only actually turns off the heating in the summer. In the winter the wall thermostat does nothing.

There is another way, still analogue, this time the thermostat connects to the boiler ebus, OpenTherm is the most used system, this allows different makes to work with each other, but some makes don't allow third party thermostats to be used.

And now to another method, Hive have a "heat on demand" system, not sure how well it works, but the idea seems good, the TRV head sends a signal to the wall thermostat which in turn runs the boiler for 1/2 hour each time it gets a demand, this means the return water temperature controls boiler, and the thermostat keeps boiler running if any linked TRV head says it wants heat, so in this case it does not matter what room the thermostat is placed in.

There are other systems, EvoHome is about the best know, it calls it a wall thermostat, but really it's a hub and each room is individually controlled.

As you can see from what I have said, the main control is the TRV not the wall thermostat, the older wax TRV heads are a bit useless *123456 does not really help setting the temperature, nor does it help when not programmable, however the TRV heads that link to the wall thermostat are around £50 each, however stand alone units like the eQ-3 and Terrier i30 can be found as low as £10 each, I got some bluetooth versions of the eQ-3 at £15 each.

So theory for me was 4 Energenie MiHome programmable TRV heads linked to follow the Nest gen 3 thermostat, and 5 bluetooth eQ-3 heads in bedrooms and kitchen. However two problems, one the heads often don't follow Nest, some times it works, but not all the time, and the TRV head needs setting 2°C below wall thermostat, so I could have used eQ-3 TRV heads for all radiators, and saved myself £140.

I have talked about a modulating gas boiler, oil boilers in the main don't modulate, they only switch off/on, it's called a mark/space ratio, and the radiator needs to hold more water so it holds the heat for longer again to reduce the hysteresis.

There are also special radiators, the fan assisted radiator does not have a TRV instead it turns the fan off/on, in some cases the fan is multi-speed the advantage is you don't get cold spots like I have in my hall as air circulated, they are a lot smaller, and can fit in the plinth of kitchen units, however you can hear the fan running, and they cool down and heat up quickly, so within minutes of boiler switching off, you feel it go cold.

So to original question, yes Nest gen 3 will work with a S plan and it can be configured in many different ways both mark/space and Opentherm control.

 

[Midwest]

Thanks for your very long informative reply.

I‘ll check, but doubt if my S Plan has a bypass. Main bedroom has no tvr, which is where the current programable thermostat is. All the other rooms have simple tvr’s.

My intention is to replace the existing pro’ stat, with either one which is more intuitive, or the Nest. I believe the Nest is a ‘learning‘ stat, working on people movements and room usage.

That’s why I wondering if it’s worth while spending the extra cash on the Nest.

 

[James]

It learns the schedule from what you adjust it to.
I.e if you wake at 7 am every week day and turn the heating up to 20 it will set this as a schedule for you
It also learns how long the house takes to heat up depending on outside temperature and sunlight info from the local weather stations.
Therefore on a cold winters day morning the heating may come on 10 minutes earlier than you expect so it is warm by the time the scheduled time comes round.

 

[EricMark]

With one room without a TRV then either the pump will modulate depending if it is that type or the pressure raises so more water is forced through the TRV's open or bedroom.

Last house I had a huge problem, the morning sun through the bay windows could cause the living room to hit 28°C and no amount of adjusting the TRV or lock shield seemed to improve it.

First attempt was a wireless thermostat so I could move it around, it did work to an extent, and it did show how important thermostat location was, near to the radiator was best, but the thermostat lost it's RF link and got worse and worse so did not want to spend out on another thermostat the same.

So since near the radiator seemed best place I fitted a couple of electronic TRV heads, got Energenie MiHome so they could work with Nest should I latter change thermostat, the results were good still living room got too hot in the sun, can't stop that, but only to 24°C so vast improvement.

However still a problem getting the central heating to fire up at the right time, wall thermostat was in the hall, where there was a large radiator clearly to re-heat hall after front door had been open, but no TRV on that radiator, so turn up radiator and hall reheated quickly after front door had been opened, but rest of house got cold, turn it down and hall was cold.

Everyone I talked to said you don't fit a TRV on the radiator in the room with the wall thermostat, and that room should be a room normally kept cool, down stairs, with no alternative heating or outside door, put it simply no such room existed. So in spite of being told it should not be done, I fitted a TRV to the hall.

My idea was if I set the TRV to same temperature as wall thermostat, then after front door had been opened the TRV would allow radiator to get quite hot to recover, but as target temperature is approached it turns down, so the last 2°C the radiator cools allowing rest of house to catch up, and it worked.

OK setting the TRV was not that easy as had to be same as wall thermostat and TRV did not have a °C scale, also could not change either wall thermostat or TRV as it took to much effort to get them to work together so did not want to alter, I set a stop on wall thermostat so we could turn it down to switch off central heating and then back to exactly the same place.

I had a by-pass both inside and outside the boiler, not a clue why two were fitted, but they were.

So this house decided to use Nest which should pair with the TRV heads I had brought from the other house, the idea was I could turn Nest up or down and with the follow command the TRV would also match temperature set, however it was found to be hit and miss, some times the TRV would follow, other times it missed the change.

So I removed the link, and simply set the TRV head to same schedule as Nest, then I found another problem, although both in hall, Nest near centre of house, and TRV closer to front door (in this house hardly ever used) and the TRV shows around 2°C colder to Nest, maybe where the stairs are, but it means for them to work together the TRV head needs setting 2°C lower than Nest, this seems to work.

However as said Nest is a learning thermostat, and it is at the centre of house between the doors to living room, toilet/shower room, kitchen, and dinning room plus the stair case. So if doors are closed the heat time is different to if doors open, so Nest can't really learn that well, however it has learnt a bit, and turn up temperature and it tells you how long before new temperature and it's not that far out.

So to conclude, decide what wall thermostat you want (but not actually buy it), then buy the TRV heads that will work with it, at least for rooms close to the wall thermostat, if the TRV heads will work stand alone then get them first, as to be frank you may find once they are fitted you don't need a fancy wall thermostat, clearly you don't want to buy Energenie MiHome TRV heads if your going to get EvoHome room thermostat. And if you buy the eQ-3 head then it will not link to any room thermostat, however likely that does not matter, you simply set the same schedule.

The eQ-3 only shows target temperature, the Energenie MiHome shows both current and target, however the Energenie MiHome needs a hub, and can only be set with phone, tablet, or PC. Where the eQ-3 can be set direct on the head. Also eQ-3 has open window function where it switches off radiator if it detects a sudden drop in temperature handy in kitchen when unloading shopping and door left open. I find being able to press one button to change from Eco to Comfort temperature very handy, I walk into bedroom during the day press button which lifts temperature then press dial which opens it to 80% and very quickly if boiler is running the bedroom heats up.

Although I can alter dinning room temperature with app on the phone, it's so much faffing about I rarely bother, so in real terms the cheap £15 heads are working better than the expensive £45 heads, the bluetooth on the eQ-3 will only work with one phone, so either my wife has control or me, not both, and setting the schedule is a lot easier with bluetooth than direct, but once set then I have not really used phone, as to do temporary change easier to do it direct on the TRV head.

Place I got them from at £15 has stopped stocking them, found the non bluetooth at £10 each, screwfix £20 each, just google eQ-3 and you will find them, also look at Terrier i30 which seem to be about the same. Lightwave does not have a display, Danfloss also do a bluetooth stand alone with display on the side, then you move to wifi types, Hive seems a good idea, but seen reports that like Energenie they lose connection with wall thermostat. And EvoHome has now been going a long time, and is likely the best, Tado will not tell you much about there system, so not keen on them. Drayton Wiser not sure about.

I have asked others with Nest how theirs works, and they say great, I then ask if any problems talking to TRV, and they admit they have not fitted any, same asking questions about Hive, very few seem to have fitted the TRV heads, so very little in reports on how they work. If I was installing for some one else it would likely be EvoHome as reports very good, so can be sure it will work, and £1000 for materials when the whole job costs £3000 is not too much extra, but when not paying for labour I have gone for cheap eQ-3 heads.

 

[James]

If I was to do my whole house, then the Honeywell ego home I should the way I would go, fully zoned and central control.
It’s just a bit expensive right now and the nest is doing quite a good job.

 

[EricMark]

If I was to do my whole house, then the Honeywell ego home I should the way I would go, fully zoned and central control.
It’s just a bit expensive right now and the nest is doing quite a good job.

I would agree, Nest does a good job. Even with EvoHome to use with a modern gas boiler it needs the OpenTherm bridge. At least that's built into Nest. What I would like it to find some one else who has both Nest and Energenie and find if my problem is common or not.

 

[davesparks]

It asks where the stat is fitted on set up, Im not sure if it changes anything on the program tho, or if its just there to whittle out some more information from you.

That is just to identify the thermostat in the app, it is only really relevant when there are multiple heating zones.
If only fitting one thermostat I type 'heating' in the box.