Danfoss TP700 or Honeywell CM907?

[Dan Robinson]

It is called "optimisation" in the installation manual. Parameter 8 iirc.

 

[jpm777]

It is called "optimisation" in the installation manual. Parameter 8 iirc.

Thanks Dan but the optimisation is to do with the boiler starting before official on time, not tpi.
From the literature "The thermostat will adjust the start time in the morning/afternoon so the desired temperature is reached by the start of the program period. The system will restrict the start time to a max of 2 hours."

I guess that rules the Honeywell one out.

 

[Dan Robinson]

you may be right...will have to brush up - like I say, I never worry about it and I fit hundreds of these.

 

[jpm777]

you may be right...will have to brush up - like I say, I never worry about it and I fit hundreds of these.

Thanks Dan, your advice has been appreciated. I'm just worried about the constant cycling of the boiler once up to temp heating the rads only luke warm is costing a lot as with the old analogue stat once upto temp it doesn't come back on for a couple of hours as my house always maintains the original temp for about an hour. My dt90e still starts up 4 or 5 times during this period, which is what I'm trying to avoid due to extra cost.
Thanks again.

 

[D_Hailsham]

What I am desperately trying to avoid is buying another stat that cycles the boiler all the time and unnecessarily.

TPI doesn't cycle the boiler unnecessarily.

I have a Honeywell CM927 and it will keep the boiler off for a long time between firings, once the house is up to temperature. It certainly does not always fire up every ten minutes. How often it fires and for how long will depend on the rate at which the temperature drops in the house.

 

[jpm777]

What I am desperately trying to avoid is buying another stat that cycles the boiler all the time and unnecessarily.

TPI doesn't cycle the boiler unnecessarily.

I have a Honeywell CM927 and it will keep the boiler off for a long time between firings, once the house is up to temperature. It certainly does not always fire up every ten minutes. How often it fires and for how long will depend on the rate at which the temperature drops in the house.

Interesting. Maybe a cm927 would be better as the temp drops slower in my lounge than the hall where the present stat is, so it would come on less often. I get that tpi provides a very stable temp, just I'm happy with it dropping a little more before it comes on as I'm not sensitive to the drop in temp.

 

[D_Hailsham]

Interesting. Maybe a cm927 would be better as the temp drops slower in my lounge than the hall where the present stat is, so it would come on less often.

I do think you are turning a molehill into a mountain.

The difference in the amount of gas burnt will be negligible, so it will take many years to recover the cost of purchasing and installing a different thermostat.

Just forget about the boiler going on and off and let the thermostat get on with doing what it's supposed to do.

 

[jpm777]

Interesting. Maybe a cm927 would be better as the temp drops slower in my lounge than the hall where the present stat is, so it would come on less often.

I do think you are turning a molehill into a mountain.

The difference in the amount of gas burnt will be negligible, so it will take many years to recover the cost of purchasing and installing a different thermostat.

Just forget about the boiler going on and off and let the thermostat get on with doing what it's supposed to do.

Ok. Fair do's if the gas difference is negligible, I'll stick with it. Thanks for your
patience and advice.