Glow-worm 18HXI-No Fault Code, Intermittant Problem

Hello,

I've recently bought a house with the above boiler (~5 years old). It is connected to an open vented system. It had previously worked fine and was serviced annually.

The boiler was switched off (Apr-Sept) as the house was empty. A radiator was removed during this time, the system has been bled of air.

When switching the boiler on at the main switch the green ignition indicator is briefly on then goes out (but the boiler doesn't actually ignite) and the water temperature is displayed on the digital readout and bounces around over a range of degrees C.

The fan makes a whooshing/surging noise, the whole time the mains supply is switched on and only stops when the switch is turned off. The boiler never attempts to ignite and no F code is displayed. Same if CH or HW is demanded.

On the odd occasion the rate of the whooshing noise will slow down and subside and the boiler will then light and work perfectly without any issues. If the CH demand is removed either manually or by timer, the problems will persist again when demand is back.

I've checked the condensate drain is free of blockages, the pump has recently been replaced (due to the old one getting water damaged from a leak), the remote themostat control has now been removed to eliminate it being the cause, I've reset the over-heating cut out, the feed tank has water in, the pressure displayed at start up is 0.8 bar.

Without a fault code and as it's only an intermittent problem I'm at a loss to know what this fault is. Am I missing something obvious or is it time to call a Heating Engineer in? I suspect the fan is on it's way out as this is making the strange noise (to me) described, and this would need to be fitted by a gas safe person anyway, I think?


Thanks in advance

i have found in the past that this problem is due to no air brake in the condensate

i am not saying this is the case with yours. without a multimeter and being there when it happens it can be quite hard to diagnose a intermittent fault

Thanks for that gasman.

What does a multimeter do?

I've taken the condensate trap off recently as it always seems to be full of water and the float is at the top of the trap. There were a few black bits in there but nothing major that could cause a blockage. It did seem stange though that I could fill it with water and it would often not drain-but as I say there was nothing physically blocking it that i could see.

I emptied it of condensate again today but it was still wouldn't start up afterwards???

multimeter is a electric tester and the black bits are normal

OK cheers.

Has anybody else got any ideas as to what the problem could be?

I'm thinking of getting a new condensate trap, just to check this out. I can't understand why it can be filled with water and doesn't drain itself?

How does filling the condensate trap trip the boiler out, a pressure swith?

So many questions!


Thanks for any advice