CH but no HW

9 Jan 2005
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United Kingdom
Chaffetaeux Celtic 2,20 FF. Recently cleaned heating return filter as combi was tripping out on OverTemp.(It was blocked)

I refilled the system as per manual and recharged, heating appears to work fine, but on hot water, mega noise and bangs from the boiler, the pressure goes up and the pressure refief valve blows and the pilot light goes out. Any one help ? :confused:
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Sounds like the pump might not be running in HW mode. Can you check it? If it works for CH but not HW I'd start with the microswitches on the end of the diverter valve.
Can't remember this particular model - but symptoms suggest primary side of secondary heat exchanger full of air.. Is there a bleedscrew inside the boiler that you've not spotted???
Thanks for your prompt replies on a Sunday !!! :confused:
Pump appears to be running fine on both CH and then HW
I shall go in search of bleed screws
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Part of the commisioning procedure for the boiler says 'Vent air separator by loosening sealing screw'.
Air sep is just below combustion chamber on LHS of boiler.

If the boiler is overheating at the SAME TIME as it's producing hot water, there may be a problem with some internal jiggery-pokery which changes the gas rate. To fix that, call a CORGI. OTOH, if the pump's definitely running and if the boiler overheats and cuts out before there's any significant flow of hot water, I reckon it's either air or something else blocking the 2ndary HX. (If it's on heating and you switch on a hot tap, you should be able to hear / feel the pump stop and then start again as it switches over to HW mode.)

'Fraid I can't tell you any more about it than that - never worked on one of these. How OLD is it?????
Boiler is 198o something, it is overdue for replacement, I dont want do be beaten by it !!!.
Bled and it made a difference same prob, I have noticed the temp rising to boiling !! and pressure increase so Ive shut it down.

Suddenly I have notice a therostat wire buckled and cracked.(Its the lowest of the thermostats on what looks like the output of the heat exchanger.
Would this thermostat giving no signal cause the boiler to run full gas :eek: ???
All the ones of these I've looked at have both had severe scale type problems in the primary of the secondary h/e. Making a lot of noise - singing kettle variety, especially on HW. It has a type of primary heat ex which scales upeasily too. All those you can take out and descale , along with the flexy hose on the h/e(?).
It jas an aav which is particularly leaky but if you shut it the prv passes.

Bin it :(
it is overdue for replacement, I dont want do be beaten by it !!!
What does it feel like, being beaten to death by a dead parrotxxxxx boiler?
Reality is that it's past its expiry date and has indeed expired!

a therostat wire buckled and cracked
Any damage to a thermostat wire (or capillary) will probably fail it! In this case, it will 'fail unsafe'' because pressure in the capillary turns the stat OFF.

A decent burial and a replacement boiler seem best advice here. Otherwise you'll be chucking good money after bad. And in its current state it MUST NOT be used.

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