Fitting a Room Thermostat

by **davidjl55** » Sat Nov 27, 2010 4:52 pm

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.

by **DEEARR2** » Sat Nov 27, 2010 9:34 pm

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.

by **davidjl55** » Sun Nov 28, 2010 2:51 pm

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.

by **sparx** » Sun Nov 28, 2010 4:48 pm

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

by **davidjl55** » Sun Nov 28, 2010 5:36 pm

Thanks for that sparx.

by **trophy3681** » Sun Dec 05, 2010 10:06 pm

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.

by **sparx** » Tue Dec 07, 2010 7:52 am

[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.