Alpha 280e Boiler Short Cyling

londonboards

Yes, another boiler short cycling thread!
I have an Alpha 280e boiler.
It gets the radiators up to temperature quickly. The radiator return pipe is hot, not as hot as the outflow but hot. After it's up to temperature, the boiler will fire for 30 seconds then cut off and go through its 3 minute wait cycle and fire again for 30 seconds or less. Water and radiator thermostats on about half way. Turning the radiator water temp down decreases the radiator temps but increases the number of times it cycles on and off.

New parts fitted to date:
Main heat exchanger
Plate Exchanger (water heater exchanger - no crud in old one)
2 x thermistors
1 x flame height probe
Over heat thermistor
Air bleed valve
New PCB

I'm thinking the burner is kicking out too much heat. Although the modulation works well I don't know if gas pressure is still too high. Do I need a gas pressure test?

Or is this type of cycling OK?

Radiators get up to heat (hot to touch) in all rads and hot water works well. So I'm thinking water flow through the radiators and the pump is good.

Fan seems to work OK but maybe its not getting the burner heat out quickly enough.

Any suggestions.

I'm a mechanic/engineer and I can use a voltmeter.