Boiler Cycling

[UMPS25]

I live in a very well insulated 3 bedroom house and I have a Baxi Duotec 2 28GA Combi.

I have 8 radiators and I wouldn’t say they’re huge. Tiles in the bathrooms, hallways kitchen and carpet everywhere else. House is timber framed and timber clad.

I’ve set my hallway thermostat to 21c and even with my central heating flow set to 30c the boiler seems to be cycling.

At first I thought it was an issue with the stat but I have separate thermometers (not connected to the heating) around the house and the stat temp is accurate.

The boiler can hold 22c room temperature even at a 30c radiator flow rate when 5c outside.

The radiators don’t really look oversized (compared to other houses) and they all have the TRVs open to max.

Is there anything I can do to stop my boiler kicking in every 10 minutes? I like to keep the house around 21c for comfort purposes.

Stat is a standard Honeywell DT90E

 

[vulcancontinental]

Look at the book to see if there's an adjustable anti-cycle delay, if so, lengthen it. Also check to see whether the boiler can be range-rated (heating output reduced from maximum (you might need an engineer to do this).

 

[Johntheo5]

I live in a very well insulated 3 bedroom house and I have a Baxi Duotec 2 28GA Combi.

I have 8 radiators and I wouldn’t say they’re huge. Tiles in the bathrooms, hallways kitchen and carpet everywhere else. House is timber framed and timber clad.

I’ve set my hallway thermostat to 21c and even with my central heating flow set to 30c the boiler seems to be cycling.

At first I thought it was an issue with the stat but I have separate thermometers (not connected to the heating) around the house and the stat temp is accurate.

The boiler can hold 22c room temperature even at a 30c radiator flow rate when 5c outside.

The radiators don’t really look oversized (compared to other houses) and they all have the TRVs open to max.

Is there anything I can do to stop my boiler kicking in every 10 minutes? I like to keep the house around 21c for comfort purposes.

Stat is a standard Honeywell DT90E

Your rad(s) output at 30C flow temp and 21C room temp will only emit 10% of their (T50) rated output so even without a TPI roomstat like the DT90E your boiler would have to have a very unlikely very very low minimum output to permit continuous boiler running, if your rads rated output are say 15kw then this requires a minimum boiler output of 15*10%, 1.5kw, do you know the minimum output of the boiler?.
Also the Honeywell DT90E is a TPI controller which will coninually cycle the boiler on/off even if its minimum output is less than the required output.
You can set the cycle time, yours would seem to be 6 cycles/hr which is recommend for gas fired boilers.
If your room temps are being kept where you want them I wouldn't worry about the cycling, I have a 19 year old oil fired boiler which by its very nature of flat out firing or none, has spent its 19 years cycling on/off and hasn't cost a penny in replacement parts. I don't think gas boiler makers are unduly worried about cycling, it also doesn't have a huge effect on boiler efficiency if you can believe the attachment, if the firing time is even 3 minutes/cycle then the efficiency loss is, apparently, only 1.5%.