Potterton Lynx 2 boiler not igniting

[Millhouse]

Hi this boiler has given me many challenges before, but this time I am beaten. Its actually in my ex wifes house, but I still feel responsible for it. Last week her mains RCD tripped. Upon resetting it, she discovered that the boiler was not working and asked me to come and have a look. I tried to reset using reset switch under boiler (hold for 20 seconds as I remember). Nothing happened, no warning lights flashed. I then found the 2 amp 240 volt glass fuse was blown on the back of the PCB. I replaced it, it blew immediately on power up. I checked for water lying in the base of boiler that may have caused a short. After this I replaced the fuse again and this time the transformer hummed as usual, but it would not reset or ignite. I then found two blown resistors on the PCB which I replaced with ones from Maplin. Still no joy. Finally I bought a new PCB and fitted it today, still no warning lights, nothing. All I can think now is that the transformer has failed. But at £60 for a new one, Im not sure what to do. Throwing money at this rotten old boiler does not seem right, but right now my ex does not have money for a replacement. I would be very grateful for any pointers or from anyone that has had these symptoms. Thanks for listening, Charlie.

 

[kevplumb]

pump / fan stuck possibly

 

[Millhouse]

Thanks for those suggestions, I had considered the pump being jammed, but I reasoned that the pump would not be spinning before the boiler had fired up? The system has been running for 7+ years without inhibitor!! The warning lights not working makes me think that power is not reaching the board? Looking at it today, it looks as though 240 volts go to the board via the glass fuse, then to the transformer, then back to the board at 24volts. I will try to test for 24 volts tomorrow. After reading through most of the forums about this boiler, no one has mentioned the transformer giving problems or being suspect.

 

[Agile]

The 24v supply is not often a problem on that boiler.

Its probably a very simple fault as so little is involved.

However, your comment about unexplained water shorting things is not encouraging and the secret may be in what you are not telling us.

You have apparently replace teh whole PCB which is about £200 all to no avail and a professional repair would have almost certainly been cheaper.

Tony

 

[Millhouse]

Thanks for your thoughts and I totally take on board what you are saying Tony. At this point I think that spending further time/money on this soon to be redundant boiler would be a bad idea. I was hoping to repair it so she could have hot water and heating for the next few weeks while her family are visiting. I have been told that these days it is common for old boilers to be condemned by engineers.

 

[Agile]

All of these boilers of that vintage are totally repairable however few engineers are prepared to spend the time that can be involved if they are not very experienced at fault finding and they prefer to just tell you that its not economic to repair and they should do a £2000 replacement.

They will often say that they dont know whats wrong and will need to change a lot of expensive parts and that would not be cost effective on an old boiler. What that really means is that they dont know how to diagnose faults very well.

I prefer the earlier model to yours as its more straightforward. Having said that your model is very reliable but with unexplained water leaking sounds as if it could be in quite a mess.

Tony

 

[Millhouse]

You are right, things can always be repaired if you can find a person with the patience and knowledge to do the work. My mum had a potterton lynx 2 fitted in 1994, and it seemed to have a problem every year. I soon learnt that 90% of this was the water pressure switch corroding so giving the false signal that pressure was too low. She had a PCB replaced after 2-3 years though I now believe that was just to take £300 from an old lady. Another time the boiler was making banging/rumbling noise, an 'engineer' stood and looked at it for 30 mins then said "you need a new boiler". When I came from work and heard this I called Hammond and Lamb randomly from Yellow pages. One of the bosses came promptly at 9 the next morning and found that the heat controls were set too high and causing it to overheat. He didnt even want a penny for coming out, what a nice guy!