Room Thermostat

[no66]

Hi Every one

I want to change my old room thermostat for a new digital one but I am unsure about the wiring there is a red, yellow and blue but i do not Know which is the boiler or the live I have a multi meter but have only had guidence on how to use when a earth is present.

 

[RF Lighting]

Do you know what make and model your existing and new stats are?

Have a look here. Is that any help?

 

[no66]

I see from other postings That the live will go to com and the switched to the No and the nuetral to a bloc also if I turn off the boiler at consumer unit will this cut the power to the stat ? (Danfoss stat)

 

[Taylortwocities]

You are correct with your connections.

You must check power is properly off. Take your multimeter and put it on a range that will measure 240V AC (it may say 240V ~).

Turn off power to the boiler
Carefully remove front of old stat
Even more carefully turn power back on and use your test meter to measure between the blue and the red - you should get a reading.
Also test between earth and red - you should get a reading.
Now turn off the power
Now test between blue and the red and the yellow - check no reading
Now test between the earth and the red then the blue then the yellow.
If no reading on the meter on any of teh connections then its reasonably safe to change over the stat.


Come back if you dont understand any of this, or if u get different results.

The boiler isolation switch should switch off the whole heating system but it ain't necessarily safe to assume it!

 

[no66]

Hi

Thank you for taking the time to reply.

I understand that by putting one terminal on a Earth and the other on live will give 240v reading if appliance has power running to it when using a Multi Meter.However looking at the original stat I can only see Red,Blue and yellow .......yellow being the switched so where will the Earth be.

Old Stat is a Danfoss which I am changing to a Hortsman Digital.

 

[Taylortwocities]

There should be an earth wire in the cable, sometimes they are cut off short if the stat doesnt have an earth terminal

Essentially you need to check you have voltage with the switch on. this checks that the meter is working.
Then turn power off and check all combinations between all terminals to ensure that the power really is off.

 

[bengasman]

Do you know what make and model your existing and new stats are?

Have a look here. Is that any help?

applause , very