Replacing mechanical Thermostat

[Davidc75]

Hi all,

I am looking to change my mechanical thermostat, Myson MRT1, for a digital thermostat. I have a few questions that I am hoping someone can help me with.

1) my central heating system consists of a boiler and a boilermate system. The controls for switching the heating and hot water on/off is controlled from the boilermate, therefore can I use a digital thermostat?

2) if I can change for a digital thermostat does anyone have any suggestions of which one to use?

Thank you for the help.

 

[Davidc75]

Hi.

I am wanting to change my mechanical timer on my Boilermate A Class for a Digital clock. Looking into this it appears that the replacement is a Grasslin XB216. I am struggling to find this, well for any less than £140, and I was wondering if there was a alternative like for like replacement.

Thanks again.

 

[Agile]

You can use a digital room stat.

They are all suitable for the job. None are much better or worse! The Drayton are one of the better and some say the Salus one of the less reliable.

Better to get a programmable stat!

Tony

 

[Davidc75]

You can use a digital room stat.

They are all suitable for the job. None are much better or worse! The Drayton are one of the better and some say the Salus one of the less reliable.

Better to get a programmable stat!

Tony

Hi Tony

Thank you for the reply.

Would getting a programmable one not confuse the boilermate as that has a programmable clock?

 

[D_Hailsham]

Would getting a programmable one not confuse the boilermate as that has a programmable clock?

That's easily overcome; you just have to disable the heating side of the clock. There are two ways of doing this: set it to permanently (24/7) on, or move the wire connected to the CH ON terminal to the live terminal. The CH will then be time and temperature controlled by the programmable thermostat.

You will probably not need to replace the mechanical clock as all it will be doing is setting Hot Water times, which rarely change.

 

[Agile]

A programmable stat sets different temps at different times so it is a more suitable control than a simple timeclock which is only on/off.

Tony

 

[Davidc75]

Thanks guys ill give it a try.

 

[Charnwood]

Honeywell CMT907. (CMT927 if you want to go wireless.)
6 different time periods set to - if required - individual temperatures
Intelegent - learns the optimum time to switch on heating. You no longer have to guess what time to start the heating to achieve the required temperature at the required time.
Over-ride buttons. Turn heat up or down if required. If you forget to reset the stat does it for you at the next time-period change.

 

[Davidc75]

So I got the Honeywell CM907. I currently have a MYSON mechanical thermostat with what looks like live, neutral and switched live. Can someone guide me on how to connect up the new thermostat. I tried and the heating never came on

 

[danieloverton1984]

So I got the Honeywell CM907. I currently have a MYSON mechanical thermostat with what looks like live, neutral and switched live. Can someone guide me on how to connect up the new thermostat. I tried and the heating never came on

I have a CM907 and previous stat had live, neutral and switched live. Live goes to A, switched live to B and the neutral needs terminating in a terminal block. The CM907 doesn't need the neutral wire and there isn't a "spare" block on the stat to put it in.

FWIW I set my timer clock in the airing cupboard to "always on" and control the heating solely from the CM907 stat. Basically the clock times that we used to have the heating "on" we set the CM907 to 19c and when the heating would be "off" we set the CM907 to a temp of 16c (although this can be any temp you like).