Programmable Roomstat

[danshocking]

Good afternoon.

I don't think this is a problem as such, but I'd like your opinions.

I replaced a simple roomstat with a digital programmable one a few days ago. The new one appears to be far more sensitive/responsive than the old on. Consequently, heat is now demanded from the boiler on many more occasions, but for short periods of time only (as opposed to maybe an hour at a time with the old stat).

From a comfort point of view this is great as the house temperature remains fairly constant. I was wandering, though, does this increased cycling of the boiler cause additional wear? It probably runs for less time now, but ignites, etc. more frequently.

Thanks, Dan

 

[ChrisR]

Well yes - what's the boiler you may be able to get it "modulated"?
What's the stat - if it's a Honeywell you can adjust it iirc.?

Wouldn't worry unless it's extreme.

 

[dal5band]

I think he means you may be able to adjust the hysteresis (swing) of the thermostat !! i.e. the temperature change before the thermostat reacts :

0.5degree means it will switch off 0.5 above the set temp. and switch on 0.5 below the set temp

1 degree and it will switch 1 degree above and below the set temp. - this will give you less cycling but the room temp may vary too much for you.

The mechanical thernostats can swing 2-3 degrees before they react.

 

[danshocking]

Thanks for answers so far.

The boiler is a Baxi 80e combination & the roomstat is a Honeywell CM67.
The stat appears to call for heat when it is actually at the desired temperature already, and therefore the boiler probably runs for 5 mins or so every 15-20 mins.

The instructions aren't incredibly clear, but i'll look again to see if the sensitivity can be reduced if necessary.

Thanks, Dan

 

[joncox]

We have a CM67 with optimum start, and it behaves in the same way. I can't pretend to understand how the OS works, but I know others do. There is a old ChrisR response on this - do a search.

The installation manual (NOT the user manual) will tell you how to switch on/off the Opt Start function - if you have that version of the CM67. There is a plain version, and a version with OS.

You can also change the boiler cycles per hour.

I think it's a great stat, and once you get used to the idea of OS (i.e. I want the temperature to be x degrees by 7am - rather than setting the stat to come on at 7am) I think it's a very efficient way to run a well maintained system.