Keston C25 - nobody knows what's wrong with it!

[MummyK]

Hi all,

I'm posting this as a last resort before I give up.
We have a 2.5 year old Keston C25 which is connected to an underfloor heating system and a megaflow hot water tank.
Boiler started playing up about a month ago.
Comes on, stays on for anything between 2 to 30mins then just suddenly stops (1green led on, not other leds on) and tries to fire up again 5 times then goes into lockout (2 bottom leds on, lockout red led flashing twice every 2 seconds, sometimes only 1 bottom led is on).
I've also noticed that sometimes the fourth red led (water flow supposedly) flashes a few times while the boiler is running, then stops.

I've had 2 plumbers come round, one of them from a firm called Plumb Force Direct who are supposed to be Keston specialists and charged me for call out and were unable to fix it. So at present I've lost £200 and my boiler's still dead.

They have checked condensate, flu, changed a little air outlet thing from which a tiny transparent tube comes out as that was leaking, but none of that has made any difference.

Do any of you specialists have any idea what could be wrong with the darn thing?

 

[Prof.plumb]

i might be able to help you. the leds speed of flashing is part of diagnostics. what are they doing? for example from left to right the lights at bottom are 1 to 4. one of these will flash in conjuction with red fault light. so red fault light flashes every 2 secs with diag led 1 flow overheat or circulation problem. theres loads of different scenarios so be specific and i can give you an answer.

 

[MummyK]

Hi, thanks for your reply.

it goes like this:

00X0

XX00

X = on
0 = off

The 3rd light on first row flashes red twice every 2 seconds.
The 1st and 2nd lights on second row are continually on and green.

I've looked at the diagnostic manual from Keston myself and the plumber pretty much went through every possible scenario with Keston on the phone. Last one was a blocked flu but because our flu exits on a party wall he wouldn't check it so we checked the flu ourselves and it does not seem blocked at all, still the problem remains.

 

[Prof.plumb]

right this could be a number of things. first of all where does the condense pipe terminate? outside to a drain or inside to waste? is this blocked/ frozen up? also what happens when you reset boiler?

 

[MummyK]

Condense pipe terminates inside to waste behind a kitchen cupboard.
First plumber took the visible part out and cleaned it. It was slightly gunky but not blocked. I don't suspect it could be frozen now and the waste itself doesn't seem blocked as my sink and dishwasher also use it.

When I reset the boiler straight after it has stopped it tries to fire up 5 times, fails and goes into lockout again.
If I leave the boiler off for a couple of hours and then try to reset it, it fires up, runs for 2 to 30mins, then stops all of a sudden, tries to fire up again, fails 5 times and goes into lockout as described in my first post.

 

[Prof.plumb]

I think there are a couple of things i would want to check before throwing parts at it. the diagnostics indicate there may be a low gas pressure, problem with spark gap, faulty igniter or a faulty ignition board. I personally would check that condense trap and pipe, check gas pressure and spark gap, if these were o.k i would be looking at the ignition board. FLue is possible but unlikey problem.

 

[cider]

Did the the problem happen whilst the engineer attended the boiler?
If not its waste of time them being there.
Kestons are fussy beasts which if happy will go for years, but if somethings not quite perfect they will give problems.
You really need someone whos not a 'specialist' but knows them inside out (if that makes sence ).

Someone like profplumb! (running without wire on cond is good start)

 

[cozzmic]

Check the pins on the PCB on the two rows of wire blocks that push onto the board. I have have two go faulty and it is the pins breaking away from the board giving faults. You would need to look at it with a magnifiying glass to make sure but it is something else to look at.
You can see the cracks round the pins here.

ps if you are going to look at the board remember to isolate the leccy (granny to suck eggs emoticon)

 

[gas4you]

For £200 I think I would have called out Keston/Ideal for a fixed price repair instead.

Outrageous amount of money to pay for nothing

Unfortunately I know next to nothing about Kestons, other than Ideal own them, so says it all unfortunately.

Lets hope ProfPlumb can help you

 

[MummyK]

Thank you all for your replies.

I think the plumbers did check the condense trap.
As far as gas pressure is concerned, our hob is on the same gas supply and no problems there. I have of course no idea how to do this myself!
Spark gap, maybe, however why would the boiler fire up, stop then not fire up again unless it has been left alone for a couple of hours?
Flue has been checked and is clear.
Unfortunately, knowing next to nothing about boilers I can't see myself even attempting to do all that stuff.
I will have a go at checking the board next week-end since it's the only thing I feel confident enough to do myself. Shame I don't have a little more time this week... No heating for me for another week

Is there someone reliable in London who 'knows them inside out' and won't charge me a fortune for nothing?

 

[mickyg]

Call Agile, he is an expert of all things

 

[gas4you]

You beat me to it. Contact Agile from his profile. He reckons there is no make of boiler or boiler fault that he cannot diagnose and fix

 

[Kristoflampie]

This sounds awful like a temperature related issue be it circulation, pump issues or possibly faulty thermisters, boiler fires up then runs until hot enough then waits until the overheat stat has cooled then round the houses again.
Havent checked the fault lights for the C25 in the manual so Im using the crystal ball a bit here but the underfloor pump is working isnt it?? or floor zones coming on ??...... bypasses??..... its worth a look.

 

[sooey]

I'll guess 'undergassed', not that I know much about Kestons either, but I've seen that exact fault on a c25. Was fine till they lit the hob, then off it went.

 

[sooey]

Mind you, that was a BG 'contractor' job and was on a half inch gas pipe feeding the cooker as well.