Room Thermostat

[Eggypeg]

I have just bought a room thermostat to replace an old one (50s/60s). It has three terminals - Common, Normal Open and Normal Closed (which the instructions tell me is not used). The existing wires are Red, Blue and Yellow. Can any electrical genius please tell me which wire goes to which terminal? Many thanks.

[BRIGHT SPARK]

Without testing the terminals it will be difficult.I would guess red to common blue to neutral(if it has a shunt resister) and yellow to N open.Check it first with a meter.Were any of the wires over sleeved?Was there an earth ?

[Eggypeg]

Thanks Bright Spark but I'm only a bodger and have no tester (or skills). It might help if I explain what I tried. I connected Red to Common (thinking it was live). I connected Blue to Normal Open. I ignored Yellow (thinking it was Earth and not necessary). This tripped the CB. I then reversed Red and Blue. This tripped the CB. I then had a cup of tea and a bun and stopped any more tests. The old thermostat is a Satchwell (model unknown). The new one is a Horstmann DRT2. Thanks again.

[bhg481]

What you need to do is look up Horstmann web-site and you will probably find a table on there which tells you which wires on a Horstmann correspond to which wires on a Satchwell.

[Fibonacci]

this may help
http://community.screwfix.com/threads/horstmann-drt2-room-thermostat-query.81549/

[BRIGHT SPARK]

The Horstman may not need a neutral so put the blue in a connector to make it safe...put the red in common....and the yellow in NO. However if you are a bodger get someone in.
Bhg and Fib.......all the wiring drawings in the world wont help if you dont know the polarity of your conductors.

[Zacs-Master]

I don't know how Pavel Kotla is going to help.

[BRIGHT SPARK]

.... go on then Zac....i've been up all night!

[Zacs-Master]

He's a polish conductor! ;-)

[BRIGHT SPARK]

....ok... he can go to earth.

[Eggypeg]

Well Done Bright Spark (or as I prefer to call you - Brightest Spark). It works as you suggested. Yours is the best answer and there is no need to send Zacs polish conductor over. It may seem funny (symphony) to him. Does it seem funny (seem phoney) to you. Many, many thanks

[BRIGHT SPARK]

Thanks for that eggy....just wondering if Zacs conductor worked with Sid in On The Buses.