Boiler - explosive ignition

[menwall]

Hi all,

We have a Glowworm flexicom30cx gas boiler in our third floor apartment. We bought the apartment a few months ago but only moved in 1 month ago. We called it one night before we had actually moved in and noticed a 'F22' flashing on the boiler screen which was to do with low pressure. I had to use the filling loop to increase the pressure to 1.5 bar (it shuts off if it goes below 0.5). Around a month later, we still hadnt moved in but noticed it had again 'F22'. Rinse and repeat - we increased the pressure to 1.5 and put it down to lack of use.

Since we have moved in, we have noticed over the past 4 week the pressure slowly declining. It went from 1.5 to 0.7 in the space of the 4 weeks. I have read that this may be a leak somewhere - we have no visible leaks and I have checked all the nozzles on the radiators (but admiteddly could be an 'invisible' leak).

I've also noticed when the pressure is low (below 0.9 it seems), the boiler will let out a massive THUD and it appears to be when the boiler is igniting. Very similar to this video but even louder: https://www.youtube.com/watch?v=q8EfeFkcsa4

My questions are:

1) What else apart from a small leak could be causing the pressure to gradually drop over time.
2) The bang is nowhere near as loud when the pressure is over 1.0. Is this behaviour common? (that an explosive ignition might occur if pressure is low?)

I am having the boiler serviced on Tuesday morning by a qualified individual, but any tips or knowledge sharing you can provide is appreciated.

Thanks

 

[Agile]

I cannot see any direct correlation between low pressure and noisy ignition.

We don't call it explosive as that work worries people.

Noisy ignition on start up only can indicate a water leak inside the combustion chamber.

Usually leaks are proportional to water pressure but in some cases with rubber seals they can increase at lower pressure.

Have you checked the vent to the pressure relief valve for dripping?

So tell us what the engineer finds.

Tony

 

[gazdaz36]

I think both your problems are unrelated. Common problem for pressure loss is the rubber flexible hose in the back left hand corner just below the main heat exchanger. As for loud ignition there are a few things that can cause this and will need looking at by your service guy.