O/T att any heating/electricians

[westie69]

I want to replace the old room thermostat,perhaps for a digital or a more up to date one.

Is there any thing i need to know when looking for one?

Is it a straight forward job?

TIA

peter.

[Bones]

Usually straight forward, if you are replacing with a digital type check that you have a neutral supply at the existing stat.

If your planning on a programable type I'd go for a Honeywell, cost a bit more but worth it.

[westie69]

The old thermostat is a switchmaster,i have found the fitting instructions and it says,

1   common

3   demand

5   earth

I have not taken the unit off the wall yet to have a look at the wiring colours.

TIA

Peter.

[Xtreme Kermit]

looking to do this myself as the set-up I have currently sucks compared to my old house.

My recomendation is a wireless timer/controller. Allows a number of control points over a seven day period and doesn't have to be near the orignal wired up point.

Had one of these previously. Variable temperatures at different times of day saved me a fortune in gas.

[Darrell O'Neill]

As the above post says...

check which type you have first, some do have a neutral, some don't.

Digital ones and programable are availible in both types, but IIRC they are different and can't be interchanged.

FWIW, i've fitted more than most and I must admit the simple mechanical dial types are far more reliable. Programming the heating is best done at the boiler or source.

[Darrell O'Neill]

The trouble with programming the room thermostats is that the system tempature is goverened by the tempature of the room that the thermostat is located. In my own house, (2 storey, 4/5 bed, 5 yr timberframe) I did'nt fit a room thermostat, i rely on the TRV's (thermostatic radiator valves)

I programme the heating times and hot water times for a two channel programmer

[westie69]

BTW it is a glow worm fuelsaver boiler,if that makes any difference?

TIA

Peter.

[Darrell O'Neill]

Peter, with the terminals that you've said, it'll be a stat 'without' a neutral. whast they call a 2wire system. Any thermostat for '2wire' systems will do, be it programmable or normal mechanical will do...

prgramable

mechanical

[Flappa]

For a start I am no expert, but....

I'm looking at this myself ATM since moving house last year. My current set up is quite old (est 15 yrs or so). It has a simple mechanical dial stat in the hall.

This has the disadvantage of only having one set point, and the controller has limited on/off times per day.

The result is that the heating is off during the day and then it has to work like billio to warm the house up when we get home. The stat is also not all that accurate with the 'dead band' of operation of around 3-4 degrees. This means that the temperature is allowed to drop too far before the boiler kicks in so it has to work hard in bursts to get the temp back up, then it over shoots and wastes energy going the other way. A digital stat will be much more accurate with virtually no dead band.

My plan is to install a programmable stat that will do all of the hard work. I can then set my system controller to continuous running. Longer term I'll upgrade the boiler, but that's another subject in itself.

My stat is a 3 wire unit with a 240v feed (blue & red wires), with a yellow wire that is live when the stat calls for heat. Other systems have only two wires with 'volt free' contacts so you need to be sure what type you need. Get the data sheet for your current unit as a starting point, and have a look at the wires inside, taking the necessary precautions of course.

I am planning to use a heat miser unit...

heatmiser

This will allow us to set a reduced temp during the day, say 15 deg, which will prevent the system having to work too hard to raise the temp back up to 18 deg before we get home. This unit will also 'learn' how long it takes to raise the house temp so that it optimises when it turns the system on. I know that it will use energy keeping at 15 degs, but it should use less while maintaining a steady temp compared to the current on/off operation.

Hope that helps.

[Darrell O'Neill]

Flappa,

The heatmiser unit is exactly the same as a 'osma' branded stat of which i've fitted dozens (possibily hundreds).... (all supplied by the customers i must add,)....

I've lost count how many i've had to replace (many under warranty).

Just my opinion, of course, and in no way am i making judgment on their quality, but i have found them unreliable.

Infact i had to change one at 9pm on fri night in a holiday barn, the heating would'nt work at all with the unit faulty..... and lets just say calling me out at that time was'nt cheap....

[westie69]

The thermostat is just a stand alone unit,as i have a seperate programmer.

what are the pro,s cons of a combined unit??

TIA

Peter.

[Mike H]

For a start I am no expert, but....

I'm looking at this myself ATM since moving house last year. My current set up is quite old (est 15 yrs or so). It has a simple mechanical dial stat in the hall.

This has the disadvantage of only having one set point, and the controller has limited on/off times per day.

The result is that the heating is off during the day and then it has to work like billio to warm the house up when we get home. The stat is also not all that accurate with the 'dead band' of operation of around 3-4 degrees. This means that the temperature is allowed to drop too far before the boiler kicks in so it has to work hard in bursts to get the temp back up, then it over shoots and wastes energy going the other way. A digital stat will be much more accurate with virtually no dead band.

My plan is to install a programmable stat that will do all of the hard work. I can then set my system controller to continuous running. Longer term I'll upgrade the boiler, but that's another subject in itself.

My stat is a 3 wire unit with a 240v feed (blue & red wires), with a yellow wire that is live when the stat calls for heat. Other systems have only two wires with 'volt free' contacts so you need to be sure what type you need. Get the data sheet for your current unit as a starting point, and have a look at the wires inside, taking the necessary precautions of course.

I am planning to use a heat miser unit...

heatmiser

This will allow us to set a reduced temp during the day, say 15 deg, which will prevent the system having to work too hard to raise the temp back up to 18 deg before we get home. This unit will also 'learn' how long it takes to raise the house temp so that it optimises when it turns the system on. I know that it will use energy keeping at 15 degs, but it should use less while maintaining a steady temp compared to the current on/off operation.

Hope that helps.

You've lost me on the permanent running heating vs heat only when you are in.  I would like to see your gas/oil/lpg bill !

Mike

[Flappa]

Mike,

The point is that the programable stat takes over the heating control because it allows multiple temperatures & on/off times each day. My current setup allows a couple of on/off times but the stat has only one setting (unless someone is there to keep adjusting it   ).

So the take my current heating controller out of the loop it has to be on continuously, the heating is then controlled by the stat which should actually reduce energy consumption.

[Mike H]

I would be interested to see the results.  Hope it works out that way but I'm not too sure of the physics.

With this setup can you, with a bit of experimentation, reduce the temp of your c/h water?

Do you still have a single rad that has no stat valve on it and what happens to that/in that room under permanent running?

Mike

[Flappa]

Mike,

I'm sorry but you haven't grasped the concept. The system is not continously running. You simply set the heating to run continously on the main controller so that IT no longer controls the on/off times, the new programable stat does that. The system runs as normal controlled by the stat but with more controlability, accuracy and thus efficiency.

The hot water is still controlled by the main unit and is not affected by this change.