replacing Honeywell CM51 with CM907

[pidgeon1]

Have you installed a Honeywell CM 907 Programmable thermostat ?

I am replacing Honeywell CM51 Programmable thermostat with the above as a direct replacement .

I have a oil boiler : do I need to go into the Installer Parameters category 2 and set :
min boiler on time ot 4
Cycle rate cr 3

any info as to what these settings do ?

What happens if I get these wrong ?

As my last programmable CM 51 did not have these additional settings.

Many thanks for any help

 

[madammim]

I recently lost my Honeywell programmer - I had no idea which model it was - but I replaced it with the CM927. I first googled to check that my existing relay box that it talked to was compatible (it is a R6660D - I had to carefully take front cover off to find the model number).

I also have an oil boiler and the parameters I set were the same as you are saying.

I am not sure if any of that is of any help to you but when I then had issues with my heating system I emailed Honeywell to rule out the new controller being the problem (which is wasn't).

They were very helpful and informative and their email address is:
[email protected]

 

[D_Hailsham]

Never heard of the CM51, do you mean the CM61? If so, this does have the Ot and Cr Parameters.

As for what they do, read Honeywell's FAQ on TPI Functionality.

Yes, you should set them to the correct values for an oil boiler will

Nothing will happen if you get them wrong, except it will take the controller longer to achieve the correct settings for the house. The values you set are just a starting point and they can be altered by the built-in logic of the controller.

 

[pidgeon1]

Thanks for your helpful replys.

The CM61 is a one day prog CM51 7 day prog

I will follow what the book says, have to ask these questions.

 

[D_Hailsham]

The CM61 is a one day prog CM51 7 day prog

Don't know where you got CM51 from, but the seven day version is the CM67.

 

[pidgeon1]

The CM51 must be 15 years old

 

[Charnwood]

Untitled

• Charnwood
• 4 Jan 2014
• 1

 

[pidgeon1]

Thats the one, has given great service 15 years can't complain

 

[pidgeon1]

CM51 Replaced by Chronotherm CM907.

This is a lot more user friendly and seems to respond quicker to temp changes, is it me or is this keeping the house warmer !!

set the Ot and Cr Parameters as instructions for oil burner



I would recommend this unit

 

[D_Hailsham]

CM51 Replaced by Chronotherm CM907.

is it me or is this keeping the house warmer !!

More likely that it is maintaining a more constant temperature.

I have had one for nearly seven years and the internal temperature is a constant 21C, irrespective of the external temperature.

Drop the target temperature by half a degree and see if anyone notices.

Have you noticed that the radiators are cooler?

 

[pidgeon1]

If anything the rads seem hotter.

boiler does fire up for shorter periods.