I have an electric thermostatically controlled convector heater in there to keep the frost away so have none of the problems with paraffin heaters.
When we built the green house we also put three courses of bricks down fist so the whole green house is taller than most. I have four automatic openers on my windows so as soon as it gets too hot they open and release excess hot air. The Electric heater will also have turned off a long time before this too so again none of the problems that normally come with paraffin heaters on 24hrs a day.
I check my propagators every day and remove any condensation as and when it builds up.
So far this year I have been very lucky.