New room thermostat

[nobackwheel]

Hi,

I'm trying to improve our new home's central heating, and have been recommended by a work colleague to get a Programmable Room Thermostat. I don't quite understand all the terminology, so i have a few questions;
Can i just replace my old mechanical thermostat with anything?

What does volt free mean?

Wiring-wise - do i just replace the existing with new?

What do I do with the current timer which turns the CH/HW on/off - does this need to be by-passed, or does it get set to ON all the time?

Thanks

Steven

Thanks

 

[kevplumb]

Can i just replace my old mechanical thermostat with anything?

err no it depends what you have at the mo (if only it was that easy)

What does volt free mean?

there is no link to mains voltage inside

ie its just a switch the wiring provides the power to switch

Wiring-wise - do i just replace the existing with new?

not usually

What do I do with the current timer which turns the CH/HW on/off - does this need to be by-passed, or does it get set to ON all the time?

either

 

[nobackwheel]

thanks for the quick reply
so in order to proceed, what do I need to check with my current system?

Have a look at the room thermostat - check the wiring - what am I looking for?

When you say 'either' - what do you mean. I only want to replace the thermostat in the room.

I'm assuming that;

The room thermostat is a switch - when temp drops, the switch is 'live' this tells the boiler (via the programmer) to turn on?

If that is the case, there is a wired connection between the room thermostat and the programmer?

How does the room thermostat 'over-ride' the programmer - do I basically leave the programmer set to 'on'

 

[kevplumb]

look for how many wires you have

you can leave the existing timer on constant or link it out

he room thermostat is a switch - when temp drops, the switch is 'live' this tells the boiler (via the programmer) to turn on?

If that is the case, there is a wired connection between the room thermostat and the programmer?

How does the room thermostat 'over-ride' the programmer - do I basically leave the programmer set to 'on'

yes

yes

yes

 

[Adrian80]

Watch what you buy,

when they 6 on/off it really means 6 times which temps can bet set.

Also you need to make sure the thermostat can be set to a low tempature of say 5 degrees.

therefore with 6 on/offs you can have 3 on's 3 off's with frost protection at 5 degrees.

i just bought this one, and it seems to work well. I did try a cheapy from screwfix. the frost protection was 5 degrees but the lowest temp you could set the stat was 10 degrees, what a joke.... also 5 on offs is rubbish you need the six...

http://www.screwfix.com/prods/76816...Controls/Drayton-Digistat-3RF-Room-Thermostat

the wiring is fairly simple. they seem to all have common, call for heat , call for cooling. You just ignore the call for cooling.

Also live neutral for the receiver.
all fairly easy to do.

 

[kevplumb]

who mentioned wireless

check the forum for the no of faults/ problems people have with them

 

[nobackwheel]

thanks for all the replies

I agree, wireless not needed - I don't think...the thermostat is already there and wired in, so might as well use that?

Will have a look at the wiring into the current stat, and take it from there.

 

[kevplumb]

what make / model boiler

 

[nobackwheel]

It's one of those dodgy Potterton boilers that everyone on the internet says keeps breaking!

Not a combi

As an aside - the whole system needs a bit of an MOT. What else would you suggest is a DIY job?

Clean it?
Add some of that treatment?
Balance the system (some Rads aren't very hot)

anything else?

 

[nobackwheel]

Update:

got around to viewing the wires in the current thermostat

it just has normal twin and earth - red/black/earth

What kind of replacement will work with that?

thanks

 

[D_Hailsham]

Update:

got around to viewing the wires in the current thermostat

it just has normal twin and earth - red/black/earth

What kind of replacement will work with that?

You said you have a Potterton boiler. Which exact model?

What is the make and model of your existing thermostat?

Wire colours mean nothing - it all depends on how they are connected up.

 

[nobackwheel]

Boiler is a Suprima L

The current programmer is a Drayton Tempus Seven

I'm not sure what the thermostat is - I think it's a honeywell, it's old

 

[D_Hailsham]

Boiler is a Suprima L

That model needs 240 volt to turn it on. So you can use either a mains of a volt free programmable thermostat, but the wiring is slightly different.

The Drayton Tempus Seven will be retained to provide HW timings.

I need to know what the three wires of the existing stat connect to; then I can tell you how to connect up your new prog stat, though it might be best if you bought that first. The Honeywell CM series are very good, they come in 1 and 7 day versions, in wired and wireless version.

 

[londonboy]

Boiler is a Suprima L

That model needs 240 volt to turn it on. So you can use either a mains of a volt free programmable thermostat, but the wiring is slightly different.

The Drayton Tempus Seven will be retained to provide HW timings.

I need to know what the three wires of the existing stat connect to; then I can tell you how to connect up your new prog stat, though it might be best if you bought that first. The Honeywell CM series are very good, they come in 1 and 7 day versions, in wired and wireless version.

Surely a twin and earth would indicate a live and a switchline?

 

[bengasman]

Surely a twin and earth would indicate a live and a switchline?

That is a rather dangerous attitude; indications/guesses and "should be's" can get you killed.