How should a boiler control it's internal water temperature

[Cavester]

Hi,

Wonder if anyone can clear this up for me as I cant find how it should operate from the manual.

I have a Worcester Bosch 42CDI Classic.

My question is how should the boiler maintain its water temperature for heating if the boiler heating dial is set to 75 degrees. Assuming the thermostat in the house is continuously calling for heat.

Should it:

A. Heat the water to 75 degrees and maintain 75 with the boiler continuously maintaining that temperature.

B. Heat to 75 then shut off let the figure drop down to around 30 then fire again until it's back to 75 and then continue to shut off and loop in this fashion?

Thanks.

 

[Cavester]

No one know this one?

 

[Chuck]

A. Heat the water to 75 degrees and maintain 75 with the boiler continuously maintaining that temperature.

B. Heat to 75 then shut off let the figure drop down to around 30 then fire again until it's back to 75 and then continue to shut off and loop in this fashion?

It'll do (A) in cold weather when the circulating water is able to transfer at least the minimum boiler-output (typically 8kW) to the radiators. It'll do (B) in relatively warm weather when the heat demand from the house is low.

If it's doing (B), i.e. short-cycling, reducing the boiler temperature will help and save energy by reducing the return temperature an increasing the heat-recovery by condensing the flue-gas.