Computherm Q7 RF wireless thermostat

[falkirkbairn11]

Is a Computherm Q7 RF wireless thermostat suitable to connect to a Worcester Ri 24 boiler?
I want to replace a Honeywell CM927 wireless thermostat which is playing up.
The Q7 RF manual states that it is suitable for connecting to any boiler that has a double wire connector for a room thermostat and the diagram shows two wires going to the boiler but the present CM927 only has one wire connected to the switched live on the boiler.(via the wiring centre)

 

[flameport]

Yes, it can be used. Wiring is identical to the existing receiver unit, which will have L&N supply and L out to the boiler.

 

[D_Hailsham]

I want to replace a Honeywell CM927 wireless thermostat which is playing up.

In what way is it playing up?

 

[falkirkbairn11]

It is not responding to temperature changes .IE temp is 2 deg above setpoint but it is still switching the heat on. Same the other way round - below the SP but not switching on. Renewed the batteries but no difference.This has been a gradual deterioration over the last 6 months so I am looking at renewal.

 

[falkirkbairn11]

Thanks flameport but I still have a query. Is it OK to have mains voltage on the reciever unit relay? That manual says that the receiver unit has a potential free alternating relay

 

[D_Hailsham]

It is not responding to temperature changes .IE temp is 2 deg above setpoint but it is still switching the heat on. Same the other way round - below the SP but not switching on. Renewed the batteries but no difference.This has been a gradual deterioration over the last 6 months so I am looking at renewal.

That's not normal. I have had a wireless version of the same stat for nine years and it has never exhibited any fault.

Has anything changed or any work been done on your system in the last six months?
Has the insulation been improved in your house?
Which brand batteries are you using? Are they rechargeable (I hope not)?

Yes , you can put mains voltage through the relay. It is called 'voltage free' because it does not automatically carry mains voltage; you have to make the connection, if required by the boiler.

 

[falkirkbairn11]

Thanks DH I've tried standard durocell and also industrial durocell (in at the moment) but am willing to try any recommended

 

[D_Hailsham]

Duracell are fine.

I take it that there have been no changes to the system.

 

[bernardgreen]

Have you or your neighbour installed or started using other wireless equipment ? Blocking of the wireless channel is a possible cause of intermittant faults.

 

[falkirkbairn11]

Thanks for the replies guys. My system hasn't altered in any way but I have never really been satisfied with the Honeywell CM927 since it was fitted and it has been getting less satisfactory in the last few months.
I was not really not looking for solutions to the CM927. I wanted to try another wireless stat to see if there is any improvement and wanted to know if the Computherm Q7 was suitable. It would appear from your replies that it is. I will go ahead with replacing the stat and post the results of any improvement or otherwise in due course.

 

[simond]

Replacing a CM927 with a Computherm is like replacing a Mercedes with a Wartburg.

The design would look in keeping with any modern house - from the 1970s. Still, you can't buy cheaper, Mr Falkirkbairn.

 

[falkirkbairn11]

I've no particular love of the computherm stat. It is just the fact that the CM927 is not doing great and I wanted to try something else.
I've looked at reviews of Salus, Drayton and others and can't seem to find any that has'nt got negative reviews so this is just a stab at trying to get my system working better. As you say it is not expensive so if it is not better, I can reinstate the CM927 or try something else. If there is a stat on the market thet you recommend I will certainly take a look. (please don't say the CM927)