Swapping thermostats

[Ross Banner]

Hello,

Looking for some advice, I recently had to call upon a well know heating and plumbing insurance company to replace a faulty digital thermostat. They replaced it whilst I was on holiday with an analogue one. Which I was not pleased about for obvious reasons. I needed to establish a price to get this changed back to a digital one as they refused to come back to fit one. When I looked behind the fascia to see what wiring was there to support that I found 3 wires. 2 in the therm and one exposed and unlabelled. At this point I am really disappointed and thinking its not safe and whether or not they have done there due diligence or whether a digital and programmable (which I had before) can be fitted now. Does anyone have an opinion or knowledge on this? Thanks very much. Ross

 

[buzzlightyear]

I will not try be to rude ross. I think you might be biting of more the you can chew .
do you self a favour get a spark in.

 

[Ross Banner]

Thanks for a very quick response!

Agreed, I have no intention of messing with this lot as I don’t have the know how. The idea of checking behind was to see what kind of thermostat I would need (research only). The thing for me was I wanted to get a bit of a clue from someone who did know, is this potentially dangerous I.e. urgent that I need to get said insurer back out sharpish. Thanks.

 

[Leesparkykent]

The bare conductor is the CPC and should be sleeved green and yellow and terminated in the far left terminal. The thermostat should ideally have a neutral which you don't have. The reason you should have a neutral connection with a mechanical thermostat such as the one that has been installed is to reduce the hysteresis of the bi-metal strip. With a line and neutral connection, the inbuilt resistor will heat the bi-metal strip in the thermostat so you don't get a big swing in temperature. Without this you will likely get a swing in temperature of around 3 degree above and below the desired set point before the heating turns off/on. With a digital thermostat, which you say you had before, you wouldn't usually suffer much hysterises as they are normally accurate to 1/4 to 1/2 a degree.