bubbles65 said:
I think some combis need ventilation, so check wether the cupboard has vents or not first
not any more mate..
theyre all sealed systems with balanced flue's, means they take their air intake from the outer ring of the flue, which also keeps the flue cool...
when you look at a boiler flue pipe next you'll see its one inside the other, the inner one is exhaust, the outer one is intake...
the entire burner box is 'room sealed', means you cant get co poisoning, its also why they have a fan.
if the fan doesnt kick in, theres not enough air flow to the burner, or 'pressure', the boiler will sense it and wont open the gas valve and 'lock out'...
if youve got one that aint like that, its f'ckin ancient and wants replacing..
the condensing thing is something else entirely, just means that some of the heat from the exhaust gas gets used to heat the c/h side, which condenses on the heat exchanger and needs to be drained via abs plastic pipe to waste, because its acidic...