Keston Celcius 25

[Jack155Q4]

We have a small flat with under floor heating and a Keston Celcius 25 in a pressurised system. Having read many horror stories on here I still can not find a definitive solution.

The problem started when the boiler stopped igniting properly. It would try and fail 4 times then give up with an error code "Failed to light, try again then call service engineer".

When failing to light I could hear the very fast clicking/snapping noise which I assume is like a spark plug. I did manage to get it going again simply by turning it off and on again about 4 times. Now it is quite temperamental. When it fails to ignite is makes a strange gasping noise and the body flexes a bit as if air was being blown inside it in very short quick bursts.

It has been like this a couple of days but now the pressure is all disappearing - I can top it up a mains tap but it won't last the night. One of the red release valves I can hear which is directly below the gauge has a very very slight weep - I had this about a year ago but then suddenly it stopped. I presume some sediment manages to get in to the mechanism of it.
This could be where some of the pressure is going. However I heard a noise from the boiler yesterday that concerned me. Once I topped up the pressure I could hear a faint drip every 10s or so from inside the boiler - sounded and almost felt like it was hitting the bottom panel. This would be another way for the pressure to release I think but I can not see any excess water anywhere. This was not like the trickle of water you can get out of one of the plastic pipes leading out of the boiler (not sure what that is).

Any advice on what to do would be appreciated. It was installed 5 years ago. Keston (who are down the road) have given me 2 numbers of engineers, both of which do not answer. I am in Bromley, Kent.

Many thanks,
Jack

 

[combispecialist]

either get on a heating contract or have the boiler replaced,these are a bag of nails and its gonna cost u a fortune in parts cost over the years if u havent got a contract

 

[Jack155Q4]

It is a lot of up front cash to replace.

Is something like British Gas HomeCare Flexi 300™ worth it's money?

I think I might have to pay to get this fault sorted and then go in to a plan. So, in general, are British Gas a safe bet to call out?

 

[combispecialist]

Yeah get on contract with british gas,its a safe bet if u cant afford 2 replace it.when these get 2 a certain age they breakdown consistently all the time.parts are very expensive for them

 

[Keston]

take the casing off and have a look.

could be the AAV just letting by although this wouldn't normally account for your failed ignition.

On top of the condensate trap (gray plastic block bottom right of the boiler) there will be a yellow wire, this can be cut to test if there is an issue there (this will have to be reconnected) if it does cure your ignition problem then replace the trap.

with any luck your not looking at an expensive fix however this is best case scenario, to be honest we could be looking at a failed heat exchanger.

 

[Boilerman2]

It does when the watter is p*****g all over the Electrode & lead!!!

 

[ollski]

These horrible things are always leaking from somewhere, usually the heat exchanger seal on the left hand side drips and takes out the ignition board eventually. Sometimes just nipping up the nuts can cure the leak as they aren't locknuts and have nthing to stop them shaking loose.

 

[htgeng]

I think keston man is probably spot on when he mentions the heat exchanger gone, especially as you are losing system pressure.

The C25 is now obsolete so if its an expensive repair you would be advised to replace the boiler rather than keep throwing money at it.

 

[Keston]

It does when the watter is p*****g all over the Electrode & lead!!!

should have a plastic tube that takes it to the bottom of the casing, although this wont stop the rusting

although thinking about it, if you ever work on a keston and need a new AAV then always order the C36 AAV, same part but the 36 comes with the tube... dont know why but all the rest dont...

 

[Jack155Q4]

I took the £99 fee to fix with parts and labour and me taking an insurance plan after.

Well, he had a look at it.....pretty much said it was fecked and to get a new one. They will not take it on under the insurance plan, nor could he fix all the faults so my £99 is refunded and the insurance plan is stopped before it even begun.

The air purge valve in the boiler was faulty causing air to escape but also not closing when it should have allowing water out and the pressure to drop. He did something to it and now the pressure seems to remain but when the boiler comes up there is a lot of noise from the water pipes, sloshing and gargling etc. I suspect it may not be letting any air out now.

Other problems were that the heating expansion vessel will not allow any air in for him to pump up the system - not sure why he didn't allow the mains water feed to do this though.

The pressure during the past 14 odd months where I have noticed is apparently 1 to 1.5bar too high.

There was some tiny leak marks on the exhaust pipes which is a bit worrying...very silly of us never to have had a carbon monoxide meter in the flat. Will sort that tomorrow.

He could not solve the failure to ignite of the boiler. He phoned Keston (manufacturer) and they told him to cut the wire but he said no to this - not allowed etc.

As a result of all this we are looking to buy a new boiler. Provided this one is not leaking any carbon monoxide we can carry on as I can usually get it to light on the 4th attempt or so (it tries itself 4 times per attempt then locks out).

He recommended the best being a Worcester Bosch, then Glow-worm, Baxi or Ideal.

No idea what I am looking at really. To complicate things I need a twin flue type, not the singe 2 in 1 type.

Any help and advice on choosing a new boiler would be appreciated

I am off to read this as I really don't have a bloody clue when it comes to central heating.
http://www.makewrite.demon.co.uk/SealedCH.html

Cheers,
Jack

 

[Jack155Q4]

I am tempted to try just replacing the condensate trap. Are they usually an easy bit to swap. Can it be seen in the photos?

What does the yellow wire do? Will get someone more qualified than I to do this.

 

[Jack155Q4]

Touch wood, it has been fine since BG engineer left on Monday. I have the setting for hot water to "Constant" so it just tops up the tank here and there. I wonder as it is going on and off more often whether the heat retained in the boiler is causing the ignition to work better. Previously it would be 22 hours between igniting.

Also the pressure is sitting much lower as I have realised I was over-topping it up.

I wonder if this could have been contributory to ignition failure? Doubt it though.

 

[Mike4]

I am tempted to try just replacing the condensate trap. Are they usually an easy bit to swap. Can it be seen in the photos?

What does the yellow wire do? Will get someone more qualified than I to do this.

The yellow wire senses the presence of water at the terminal where it joins the condensate trap. If the condensate trap or drain is blocked, the wire senses this and prevents the boiler from running and filling up the whole combustion chamber with condensate!

Has any of your visiting technicians used a flue gas analyser to check and adjust the CO2 settings on the gas valve yet? I suspect not as when my own C25 begins to puff and wheeze on ignition (as you describe yours doing), this is the fix. I suspect the CO2 on yours needs re-setting at both low and high gas rate settings, but particularly at low rate. Keston tech will explain to your service engineer how to do this if he calls them. I'm surprised they didn't suggest this in the first place.

Cheers, Mike

 

[Jack155Q4]

On top of the condensate trap (gray plastic block bottom right of the boiler) there will be a yellow wire, this can be cut to test if there is an issue there (this will have to be reconnected) if it does cure your ignition problem then replace the trap.

Finally I cut the yellow wire after a few failures to ignite and after, the first attempt, it lit. To try and prove it was not a fluke I joined the wire, it failed a good few times and then I cut it again. This time it took 3 times to get going - not instant as it was before.

If the condensate trap is reasonably priced I will look to replace it.