Ravenheat White star intermittent and now not firing

[raychmike]

As thread title says. Ok I am a trainee gas engineer and currently undergoing my 80 hours gas diary. I work alongside a corgi engineer and he asked me to go take a look at a boiler for him (as above). Fault was, initially the boiler would fire up run for about 30 seconds and then go cold again (DHW side). I didnt see this first hand because when i arrived I was met with the red flame light on and they have had no heating or water since yesterday. Turn the hot tap on and the fan starts and i hear the ignition sequence clicking away (but no sparks) and then it fails and red lights. Turn on the CH and nothing happens it is just dead. I am tempted to change the thermistors but would like some further advice before ploughing in and getting it all wrong.
Yes I could just ask the engineer I work with but he isn't going to be overly impressed if i go running back to him every time things get a bit tough. So I am running to you guys instead lol.

As a side note there has been a minor leak on the flow to the boiler and the pressure drops over time, the home owner has been, in his words (draining the boiler so that needle shoots round). My guess he's been topping it up until it blows off. Also the AAV is leaking but this didnt surprise me as the boiler has been running at 3 bar ever since mr home owner started "draining" the boiler.

Other info
The pump is free and seems to start
The flue fan starts (at maximum speed?? how can i check?)
System fails and red flame out light illuminates

Thanks in advance

 

[bellairaphon]

not worked on that boiler, have you?

checked continuity on ignition lead??
checked gap on spark put a screw driver in n see if it arcs of that
then if not ignition pcb if seperate id go for pcb.

try tighten the nut if its on a joint.
if he's puttin too much pressure in have a quick check on the prv see if its dripping n while ya at it check his expansion

 

[Rob]

I'd say wait and till your able to work on other people's boilers legally

 

[raychmike]

not worked on that boiler, have you?

checked continuity on ignition lead??
checked gap on spark put a screw driver in n see if it arcs of that
then if not ignition pcb if seperate id go for pcb.

try tighten the nut if its on a joint.
if he's puttin too much pressure in have a quick check on the prv see if its dripping n while ya at it check his expansion

Thanks for the reply
Firstly no i have not worked on it my engineer had the front off and left me to scratch my head. He is working on an unvented system next door which ironically I am the only one qualified to work on. But he is fitting the boiler next door and said if you can work out what's wrong with that ill give you a pay rise lol. I think it has been haunting him for quite some time. There isn't much I can do and will (with supervision be making the repairs if and when we/I work it out). PRV was fine and AAV leaking through the actual body (a hair line crack) so that needs replacing. Thanks I will give those other suggestions a try.

@ rob thanks for your suggestion but if you read the post I am currently working my 80 hours out so that I can become corgi registered. I am working with a qualified engineer and make no repairs unsupervised however he does allow me to fault find (without removing parts etc). In order to learn my trade I require to do it mechanically ie on the job as this is the only way to learn a skill. Please if you have no constructive advice then why offer up this kind of comment. We all have to start somewhere

 

[holty]

look at the aps(air pressure switch)hoses for a start or ........

 

[raychmike]

look at the aps(air pressure switch)hoses for a start or ........

Thanks already gave them the once over but will have another look in the morning. I only got chance for a quick once over as we had all but finished for the day, maybe tomorrow i will get chance to have a proper look. And of course if i need to remove the combustion case I will ask for the supervision of my boss. I need to suss this out as a pay rise depends on it lol. This is a boiler I am not familiar with so I think I am being tested, either that or he's stumped himself and i suggest the latter.


PS Hope he aint a member on here lol

 

[Agile]

For a start there is no evidence that the thermistors have any involvement at all so that thought would justify a pay CUT !.

You say you can "hear the ignition clicking". What exactly do you hear?

Is the spark occuring somewhere other than the spark gap at the ignition electrode?

Follow the HT lead and ideally watch it in the dark for evidence of sparking somewhere else. Thats AFTER you have checked the HT lead is correctly terminated at both ends!

To rile the CORGI fix the boiler but dont tell him what you did!

If you were working with me and asking questions behind my back you would be sacked! I would take the view that you might be getting duff gen and becoming untrained!

Tony

 

[raychmike]

For a start there is no evidence that the thermistors have any involvement at all so that thought would justify a pay CUT !.

You say you can "hear the ignition clicking". What exactly do you hear?

Is the spark occuring somewhere other than the spark gap at the ignition electrode?

Follow the HT lead and ideally watch it in the dark for evidence of sparking somewhere else. Thats AFTER you have checked the HT lead is correctly terminated at both ends!

To rile the CORGI fix the boiler but dont tell him what you did!

If you were working with me and asking questions behind my back you would be sacked! I would take the view that you might be getting duff gen and becoming untrained!

Tony

Got the boiler fixed in the end, managed to get the boiler firing again by manually operating the APS, so I swapped that out for a new part (supervised of course) then it was back to cycling on for maybe 10 seconds then lock out. It would fire on CH ok but soon as demand for HW it went to lock out. Checked resistance and the HW sensor (thermistor) was reporting an overheat in the HE wrongly. Before changing the HW sensor I advised customer to replace both HW and CH thermistors for good measure he agreed and BINGO fully working boiler. Also replaced the leaky AAV as the water was dangerously close to the CH/HW sensors and more than likely the root of the problem. Advise customer on correct topping up procedures and pressures but if in doubt to call us in. Pat on the back from the boss and no pay rise lol, what do you expect from a heating engineer.

Hi agile, if you read my first post the boiler was cycling on then locking out after a few seconds. Hence wanting to change the thermistors but by the time i arrived it was a dead as a dodo. The clicking I refer to was the APS but I am not allowed to remove the combustion case on my own so couldn't pin it down. Since it's been fixed my boss reckons the constant cycling on/off was to much for the APS (it was on/off every 2 minutes or so while the boiler was in demand for HW) and that's why it failed, apparently it's been at it for quite some time but the customer only phoned when the chill came in, typical....!

PS The guy I work for has given me license to ask whatever questions I like to any qualified engineer as long as I don't DO anything without his say so. "I can't know everything mate, ask away" was his response. Since found out the reason he asked me to go look at the boiler. My Dad fitted it 2 weeks before he died (it was his last job as he died on holiday) and he thought it only fitting I fixed it.

Thanks for all your responses guys even the negative one's, I take my ACS in March and will continue to claw every last ounce of learning from whatever sources I can then make my own mind up (with a little help) on what is sound advice and what is not. It's been a long tough road for me since my dad died and all the years of experience went with him. Still I had a good 5 years of wet plumbing as an apprentice, or in other words I did all the crappy jobs and pipework while dad came in at the end commissioned the boilers and took the cheques lol.

Regards