Image is for illustration only and should not be relied upon Siemens RAA21 Room Thermostat

Siemens RAA21 Room Thermostat

Ex VAT: £9.99
HCO Code: 23C07
Availability:  In Stock

The RAA21.. room thermostat has separate outputs for heating only and cooling only.
If the room temperature falls below the selected setpoint, the heating contact will close.
If the room temperature exceeds the selected setpoint, the cooling contact will close.

* 2-Position Control
* Volt-Free SPDT Contacts
* 6(2)A Contacts
* 3-30C Range
* Dimensions: 97x96x35.3mm HxWxD

Direct replacement for obsolete RAA20











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Hi, I currently have this Siemens RAA21 fitted in our bedroom to control its underfloor heating. I would like to replace this with something 'smart', preferably using the Zigbee network. Would you please be able to advise what would be suitable? Many thanks
Hi I would recommend the Delta Dore TYBox 5000. HCO code 07A28. The Delta Dore is not Zigbee, but it is smart.
Hi I have an old Landis and Gyr room stat - must be 25 years old, it has three terminals with 2 wires - in the case it has a label saying 25A -can this be replaced with the above
Hi As long is it is controlling a normal gas or oil boiler, then it will be fine.
Hello, will this RAA21 thermostat work with a Siemens RWB29I controller? The existing room thermostat is a Landis&Gyr,no type marking 23yrs old and only 2 wires connected to it. I presume just an off and on switch type. I hope you can give an answer. Thanks JC
Yes. It will connect to the same 2 wires for a straight swap.
Hi, Will this work with a RWB27? I want to buy a replacement for an old RWB7 but incorporate a thermostat. Thanks, Andy
Hi. Yes it will.
Hello I have an old ACL thermostat. TA350Only 2 wire supply this, a red and a white. Do you have a replacement for this, maybe the Siemens Raa21?
Hi. Yes, the RAA21 would be suitable.
Hi! I wish to operate a small extract type fan when a room gets over hot - will this work? There is not need for it to operate the heating.
Yes it would, as long as the fan draws less than 2 amps.
Is raa21 a direct replacement for raa20? Is it wired up the same? Thanks
Yes it is. A simple swap.
I have a Siemens Raa02 room thermostat that needs replacing. Can I still obtain this item or what would be a good replacement in size and wiring. Many Thanks Lynda Denner
The RAA02 is obsolete. If it is an ordinary gas or oil boiler with wet radiators, then this RAA21 will be fine. If it is electrical heating, let us know and we will recommend something else suitable.
Will this thermostat work with underfloor heating in a house wired with a two wire system?
Yes it will.
Does this stat have max and min limiter built into it to stop the set temperature being exceeded.
Yes it does.
I' am writing for my daughter; she lives in Brighton and she has a Siemens RAA21-GB thermostat; we are looking for the same thermostat but with a clock; what type do you advise?
We would recommend the Siemens REV 24. It will connect to the same 2 wires

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