Keston C40

[patter]

Hi,

I have a Keston C40 (had to have it due to flue length). I'm just wondering I've had BG engineers round the whole time and had a lot replaced (either that or they find a load of stuff to try to sell me.) The machine however seems to constantly be going down I either get error messages

b 25 Boiler rising in temperature too quickly. Check for system
blockages

b 30 Circulation too slow. Check system for blockages

E 18 Flow overheat - check water circulation

or the machine sits idol claiming its at the correct temperature but when you reset it it comes on saying its way lower.

I'm having to reset it at least twice a day all of the radiators in the house work. It was working fine all last summer when their was no CH only DHW.

I'm fed up with calling BG and having to reset it please help.

I replaced the system 3 years ago and had PF and all the works including new rads put on.

Thanks

 

[twgas]

Do you have a return filter, it might need cleanig.

 

[patter]

Do you have a return filter, it might need cleanig.

No return filter that I can see

 

[ChrisR]

Does it have an automatic bypass fitted? Plumbers love to leave them out to save a few quid. A cracked heat exchanger often results...

 

[patter]

Does it have an automatic bypass fitted? Plumbers love to leave them out to save a few quid. A cracked heat exchanger often results...

No has a manual bypass... but over the summer it was heating the DHW quite happily in fact it heated the house happily for five days this winter before going down... it seems to only be effected if hot water is on but the rads all work perfectly...

 

[ChrisR]

What sort of bypass?? Oh sorry you said, manual. No bluudy good, Get it changed so it complies with the installation instructions! It matters!


WHen the PF was done, did they bother to clean the boiler? Plumbers often don't!

Suppose you turn the CH temperature down, is it better? You know the ch and HW should have different thermostats...?

 

[heatingman]

35mm (1"1/4) flow and returns and a 28mm auto by-pass are a must. From the fault codes it does suggest a circulation issue.
Kestons are pretty much no ones favourites and only go in due to the fluing and options. If installed on a low loss header they just plod along quite happily for years. Overheating kills them and most internal components at an alarming rate.

 

[patter]

35mm (1"1/4) flow and returns and a 28mm auto by-pass are a must. From the fault codes it does suggest a circulation issue.
Kestons are pretty much no ones favourites and only go in due to the fluing and options. If installed on a low loss header they just plod along quite happily for years. Overheating kills them and most internal components at an alarming rate.

Thats very kind I haven't seen any of this stuff on mine... what can I say to the BG guy when he returns so it comes under my BG homecare insurance rather than having to pay an added fortune... not sure I can cope with the hissy fits from my boiler much longer and might take a sledge hammer to it just to shut it up!!!!!!

 

[heatingman]

your going to have a problem as I doubt the homecare covers existing or installation faults, unless of course they fitted it. You might win in that case. They might try telling you its fitted in accordance with install instructions. Kestons installation instructions give various options for fitting
1, the basic minimum which if your lucky might work ok.
2, their preferred method which costs a lot more but does work.

You can guess which option most installers go for.

 

[ChrisR]

I shouldn't say too much to the BG man or he'll say "oh it's installed wrong then" and bugger off.

Keston tested even the bigger 55 model on 22mm pipe, just to make sure they didn't have problems. You don't get all the heat out of course, but with the right bypass they can manage themselves. A 40 doesn't need more than 28mm pipe to get full output if the systems's designed properly.

You obviously have circulation problems. Everything gets older and slows things down, so it often isn't one thing which causes a problem if the design't wrong, like yours.
You will have a worn pump, some sludge in the boiler, a bypass which is hopeless, and other odd things. So get a proper auto bypass fitted first.
The 55 needs a 28mm, not sure about a 40, but if it says 28, fit a 28, not even two 22s, cos they don't do the same. 28mm ABV is thick end of £100 iirc.
If it stiill does it, then the sensor, and pcb's suspect. Probably already changed though.

 

[heatingman]

It might be worth asking them to check which stat on control panel is running the boiler.
The top one SL1 will switch boiler on and run it at a very low rate while the PCB measures temperatures and then decides what to do, this is best option on system with unknown flow rates.
The lower one SL2 will fire boiler straight up in berserk mode and give problems if system can't absorb heat quick enough due too poor flow/circulation.

The flow/circulation through boiler and the temp rise are crucial to these things operating satisfactorily.

 

[patter]

Many thanks to the two of you I shall try to mention as little as poss on Wed when he comes back and fit a auto valve afterward to be on the safe side

 

[cider]

Shouldn't that boiler have an extra pump externally?
I thought the built in pump was just to shift water through the boiler.
Just sticking an auto bypass in is going to circulate the water back to the boiler resulting in boiler idling and no heat where its needed.