Combi Boiler Question

[petersh]

Hello,
I am new here.
Just had a new Worcester Bosch combi installed which replaced a 20-year-old swift flow.
The new boiler has separate controls for the water and central heating temperature.
How do I work out what the central heating temperature should be set to in order to avoid it short cycling? It's set to 4 which equates to approx 60c.
My house has 10 radiators, 6 of which have TRVs on.

 

[Sylvan]

Ideally all the radiators need to have a TRV

Normally when I install a heating system or upgrade one I put a thermometer on the supply and return and have the circulator run continuous

Then I try to get a 10-15 deg Delta (difference between supply and return )

Hopefully your piping is well insulated

 

[Sponsor]

 

[Dana]

Ideally all the radiators need to have a TRV

Normally when I install a heating system or upgrade one I put a thermometer on the supply and return and have the circulator run continuous

Then I try to get a 10-15 deg Delta (difference between supply and return )

Hopefully your piping is well insulated

Ideally NONE of the rads would need a TRV ( since in the ideal system they would all be perfectly sized to their loads! )

That would be a delta of 10-15 Fahrenheit, not Celsius. (Try 5-8C .)

Whether or not it short cycles is a function of how much total heat is being emitted, the amount of thermal mass in the system, and the minimum firing rate of the boiler. Radiators come in all sizes / ratings / water-volumes, and there is more than one model of Worcester Bosch combi. Without some basic information it's impossible to estimate whether setting it to 60C is going to cause it to short cycle.

If the radiators can emit the full min-fire output of the boiler with 60C boiler output it can be set up to not cycle at all, but even if the rads aren't emitting as much as the boiler is dumping in, if there is enough thermal mass to take up the difference in boiler input to radiator output the cycles can still be reasonably long (=~3 minutes or longer, for a low-mass wall-hung boiler) enough to not suffer excessive wear or lose efficiency.