Advice on replacing old manual thermostat with digital programmable type.

southcoastrgi

which ever you go for fix it to the wall wherever there is a rad without a trv (normally the hall) & don't keep walking around with it, it's a room stat not an ipod

macman

elsmandino wrote: »

Many thanks for your replies.

I in fact have a conventional boiler set up and that CM907, as recommended, looks like exactly what I am after.

One other quick query if I may - for an extra £35 or so, you can get the wireless version of that model - CM927.

I assumed that wireless thermostats were purely for convenience but there seems to be a lot on the net that suggests that they reduce energy bills instead - i.e. with a fixed thermostat, the various rooms in your house may not be particularly accurate as the temperature sensing is being carried out at a fixed point (my current thermostat is half way up my wall in our hallway, which I hope is the best place to have it).

The argument for supposed savings with the wireless version is that if you are spending time in the livingroom, you put the thermostat in there and it will actually keep it at a more accurate 18 degrees. However if you were to then to go to bed and the bedroom was better insulated (and assuming you wanted the bedroom also kept at 18 degrees), the heating would come on less as it would then take into account the fact that the bedroom was better insulated.

Hopefully you understand what I mean - my example is not as clear as I hoped when I first started writing it!

Ultimately, I would be grateful for your thoughts on whether you think there is any point in going for the wireless option or whether I should go for the CM907, which shall be in my corridor.

Thanks very much.

The CM907 was recommended by me for a combi boiler. It's a single channel programmer and is not suitable for your system, as it will not control the hot water. You need a dual channel programmer.

twokcc

southcoastrgi wrote: »

which ever you go for fix it to the wall wherever there is a rad without a trv (normally the hall) & don't keep walking around with it, it's a room stat not an ipod

IMHO like being able to tranasfer from one room to the other and if your ever bedbound you can control the thermostat from the bedroom
Use salus rt5000rf but had danfoss to5000rf in previous property thought the controls on danfoss were simpler and easier to use.

macman

On the CM907 you can use the compensation feature. So (for example) if your hall is always 2C colder than the lounge, and the programmer is fixed in the hall, you can set it up to allow for that, so that your lounge won't always be 2C higher than the temp set on the programmer in the hall.

Biggles

twokcc wrote: »

IMHO like being able to tranasfer from one room to the other and if your ever bedbound you can control the thermostat from the bedroom.

In that case, don't bother with a complex optimising programmer, as its learning program won't be able to cope with the temperature changes involved with being in the hall one minute, the lounge the next, and the bedroom after that.

elsmandino

Very good points raised.

I agree that if I want to use the optimisation feature properly, I should just leave it in one place and let it do its job properly and (as is mentioned) as the current stat is indeed in a hall way with a radiator that does not have a TRV, I should just get the wired version and replace my current thermostat.

Macman - although I do not have a combi boiler, the CM907 would seem to still be a great option. I use the current timer to control the hot water only and leave the central heating switch on permanently - allowing the programmable stat to control the heating.

Thanks again for everyone's input on this one.

Alex

macman

Yes, you could control it that way. It's a very good programmer IMHO.
However, the optimiser isn't that clever, it just seems to adjust the start-up time based on the previous day's time taken to achieve the set temp from start up. So a sudden fall (or rise) in overnight temp will fool it.
It is however very easy to set and maintain precise temps, and to use the holiday and 'day off' functions.
There is also an optional outside temp sensor available.

Ben84

A benefit to wireless is that you can easily try the thermostat in different rooms/locations until you're happy with how it works. I did eventually mount it on the wall at our last house, but only once I'd found somewhere that seemed convenient and gave a reasonable reading of the average temperature in the house throughout the day. Of course you can guess, but having the flexibility to move it if you guess wrongly is good.

nickj_2

i have a wireless digistat2 , which is a nightmare to set up , to programme it , you probably have to have the same qualifiactions to those working the hadron collider , it has 4 different time settings during the day and you can't have different on times , ie on a couple of days my daughter gets up for work at 5-30 , on days when she goes to college she gets up at 6-00 and then at the weekends we like a bit of a lie in .
once it reaches the required temp it obviously cuts out , the room seems to retain it's heat according to the stat and another thermometer , but it can stay off for a couple of hours or more by which time i've switched it to manual and cranked it up a degree or so ,