The message from Mike Clarke contains these words:
Interesting. I wonder how much of that lack of efficiency at low output is due to heat losses through the casing which presumably is not counted as useful output.
...very little I would think.
Part of the loss of efficiency is due to the fact that there will be increased excess air going through the boiler at part load. Typically on these type of boilers the fan is a fixed speed device and moves a more or less fixed air flow. Since the boiler won't cool the flue gases below about 100C (give or take) the energy lost in the flue gases is more or less independent of gas rate.
With a condensing boiler typically the air flow is proportional to the gas flow and the gasses are cooled further as well.
Na, Sex is good exercise, and doesn't (usually) stress the bones.
For a moment there, I thought Andy Hall had written that. (I am very tired at the moment and susceptible to suggestion)
God rest his soul. He is so missed.
Dave
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