DIY Doctor UK DIY Forums

Hi,
I have a Gravity HW, Pumped CH system with a Programmer, but no Room Thermostat.
I have a wiring diagram so attempted to fit a Room Thermostat without success.
The Thermostat is a Siemens RAA-20 with Volt free contacts, no Neutral or Earth required.
Just two wires, Y1 control output Heating, and Y2 control output Cooling.
After I wired it in the Gravity HW worked fine, but couldn't get the pump to switch on for the Central Heating.
Although the light on the programmer did come on.
I would appreciate it if someone could help me out.

Thank you

David.

Check the wiring connections at the thermostat sounds as if you have use the wrong terminals. One cable should go to connection L and the other to the heating output, possibly connection W.

Thanks for your help DEEARR2.
Working fine now.
Instructions were a bit misleading, and it doesn't take much to mislead me these days.
Once again....Thank you.

Use L & Y1 for heating as in your case.
L & Y2 for cooling eg air con.

Thanks for that sparx.

From what you are saying if a boiler has a programmable remote control you can also have a manual room thermostat fitted.

My parents want the heat on all the time and wish to control it manually; they cannot work the remote control.

[quote="trophy3681"]From what you are saying if a boiler has a programmable remote control you can also have a manual room thermostat fitted.

My parents want the heat on all the time and wish to control it manually; they cannot work the remote control.[/quote]
Suggestyou repost with details of their set up.
If they have a programmer /time clock just set to 'continuous/on' and set stat as required.