updating CH system advice re room stat

[jb1468]

To start I don't know a great deal about this area. I'm renovating my property and updating the CH system (very old boiler). I have a plumbing and heating engineer coming in few weeks to do the work.

I have Oil CH and am installing a conventional condensing boiler. I have a hot water cylinder. He is fitting a motorised valve to provide hot water separate to the heating system and a double time clock. I am also fitting TRV's to the rads. He first suggested not fitting a room stat, however given all the advice I read I have decided I want a room stat. I need to purchase the stat before he arrives as he is bringing all the other materials.

Hope I have provided enough context info. I have read around stats and I would like to fit a digital (for accuracy) programmable thermostat. The idea being that I set the CH programme/clock to always on and allow the stat to do the rest i.e. manage the temperature at different times.

Have I missed something or have I got this badly wrong. Will a digital programmable stat work ok with my system. Any advice on make/model? Are they any more expensive to get fitted than a basic stat. Its a basic 3 up 2 down house and am planning to fit it in hallway (will keep TRV of that rad) Any reassurance advice would be much welcomed

 

[gas4you]

What you've described will work fine.

The Honeywell CM927 appears to be the most popular and easiest to use at present, although personally I prefer the Siemens new REV24.

 

[Statia]

Honeywell CM927 wireless stat or the fixed one is the CM907.

Good piece of kit. Will do what you want it to. Will work fine with your system.

You can get the CM927 for about £90 on-line.

Should be same price to fit as any other room stat. If it's more, the feller is taking the micky.

 

[simch]

HI, sorry to hijack thread, but I have been looking at these two Honeywell stats last night.
I have an (old but reliable!) Worcester Danesmoor 20/25, oil fired, with a built in timer (two timer settings for heat and 2 for water).
System is a gravity fed system I am pretty sure, put it this way, if heating is on, so is hot water, but can have water on on its own.
We have two pumps, one for main house, one an additional bit for a small annex, and currently 2 Honeywell T40 analogue stats. These operate just the pumps, and have three wires to each, which despite being coloured live neutral and earth, appear to be just live in, live out(neutral coloured wire) and an earth. To me, (not an electrician!!) these look to be simple switches to turn on the pumps, there is no tank temp stat, but a recently replaced boiler stat that kicks in when the system water returning under gravity is at a certain temp (set by control knob on boiler).
Anyway at present it all runs ok, but we see temp fluctuations and some rooms are very cold and others seem very warm, we have thermo rad valves on most main radiators. We uses the "twice on" timer on the boiler and it seems ok, but am looking for some more controllability. I saw the Honeywell CM zone system that uses wireless motorised rad valves but its pricey. Alternatively I am interested in the CM 927 and 907. Will all these systems work with my current wiring for the stats, and am I correct thinking that these are just switches on the live side for the pumps?
Are all the stats battery operated. Anyone any idea how much more controllable it will be? Can you for example if you are dashing out for the day, turn it all down so you don't heat the house for no reason, or do you have to reprogram it.
Sorry for all the questions, any help appreciated.!!

 

[bengasman]

have used the honeywells several times and they are good, and very user-friendly. don't know what the siemens units are like from personal experience, but only heard good things about them

 

[squowse]

the honeywell cm907 (and the 927 wireless the same i expect) has a "party" function, that allows you to set a new target temperature for the following 1-23 hours. (guests and drinks not supplied). i just bought 2 (radiators and underfloor) as i think they offer the best functions and user friendliness.

the electrical connection to the system is a simple make/break switch so for example you could run live to the CM907, another switched live to a zone valve, and then neutral from the valve back to the where you took the live from making sure an earth is provided throughout.

i am not an electrican, but i believe it is good practice to use a sleeve or insulating tape of the appropriate colour to indicate if the neutral conductor in a cable is being used as a switched live.

put the room thermostat in the draughtiest, worst heated room, or the room that you want to be the warmest. i think the hallway or sitting room are the usual choices. you want to site it in the room that will come up to temperature last. don't put a thermostatic radiator valve in this room - the thermostatic valves on the radiators in the other rooms will then shut down as their rooms come up to temperature.

 

[simch]

Cheers, that makes sense. I picked one up today to try. I suppose the party mode can be made with a low temp if I am poppin out for the day when I planned on being in?
So hit the party button, party temp at 12 degrees, out I go and it's all off!

 

[bengasman]

to comply with part l, the roomstat should NOT be placed in hall or on landing. this was common in 50's but now well outdated method. install roomstat in lounge or study, provided there are not alternative heat sources in the room

 

[jb1468]

to comply with part l, the roomstat should NOT be placed in hall or on landing. this was common in 50's but now well outdated method. install roomstat in lounge or study, provided there are not alternative heat sources in the room

Why is this?...it seems quite a common thing done today. I see them in halls all the time, thanks.

 

[gas4you]

There are no regs saying it musn't be placed in the hall.

All the regs actually state is that the room in which the room stat is in must not have a trv fitted.

Usual places are the hall or lounge, but don't put it in the lounge if you have a fire that you use.