Good day,
Worcester Highflow 400 BF about 10 years old, originally fitted to new water/central heating system, has always been very reliable, from memory, new diverter valve fitted under warranty in first couple of years, since then nothing until last year replaced pilot burner tip.
Have now developed a fault(s), boiler tripped for unknown reason, CH system pressure reading about 0.8 Bar so topped up, although pilot would light, it wouldn't stay alight when gas valve push button released. Left it for a few hours relit pilot and system appeared to work normally.
Next day, boiler tripped again and noticed system pressure up to about 3 Bar, which is higher than normal. After a couple of hours, relit, however, very quickly water/CH was very hot (much hotter than normal), so shut down again and arranged local Worcester approved service engineer to attend, next day.
No evidence of safety relief having operated, no water at external outlet.
Service engineer attended and diagnosed expension vessel diaphragm gone, this presumably would explain the much higher pressure than normal (expansion vessel very heavy and full of water).
Service engineer advised replacement of expansion vessel and also possibly thermo couple and/or thyristor to solve overheating problem, advised parts should be available next day, but would confirm re-attendance to fit parts.
Got a phone call from the approved service agents later and was told that the reapir would be very expensive (about £500-£600) primarily because the expansion vessel is very difficult to access (strange as his service engineer had had the expansion vessel off earlier in day and it took 90 seconds), then advised as boiler 10 years old and inefficient (advised 60%) and likely to have further problems soon, best solution to replace with a new (guaranteed) boiler, advised that Worcester 4.5 would be best and very efficient (90%+)replacement (alarms bells here as at another family house I had a Worcester Highflow 4.5 fitted and that was before this 400 BF, so must be more than 10 years ago, estimated cost for new Worcester 4.5 is £2500 + VAT = £3000.
Having checked, it seems Worcester 4.5 is an obsolete model (although service agent said they have one in the showroom!) with an efficiency rating of 65% which is less than the actual 76% of my current 400 BF and it appears that direct replacement for my current model would be the Highflow 440.
As can be seen from above comments, although the service engineer attending appeared proficient, the approved service centre/showroom are a different matter.
Leaving aside the expansion vessel, which I can source and fit. What is the underlying cause(s) of the over heating, is it the thermocouple and/or thyristor as suggested by service engineer attending and what should I expect to pay to have one/other/both replaced?
Please note that the boiler is still functioning and heating water/central heating (only if I keep hot water running and open 5 large radiators as heat sinks to stop heat build up). Does the fact that hot water and central heating are being supplied concurrently mean that the diverter valve is malfunctioning (I was under the impression that when demanding hot water, central heating was not being supplied - which is I presume the job of the diverter valve), perhaps if temperature is enough, both are supplied, as is the case at the moment. If I shut down the hot water taps then water in central heating starts to get very hot (well, I can put my hand on radiators, but not for long), or much hotter than normal, at this point I shut down before tripping/damage.
Sorry for the long message, but hopefully the information contained therein will be sufficient for basic diagnosis.
I would appreciate advise on the above.#
Regards
Worcester Highflow 400 BF about 10 years old, originally fitted to new water/central heating system, has always been very reliable, from memory, new diverter valve fitted under warranty in first couple of years, since then nothing until last year replaced pilot burner tip.
Have now developed a fault(s), boiler tripped for unknown reason, CH system pressure reading about 0.8 Bar so topped up, although pilot would light, it wouldn't stay alight when gas valve push button released. Left it for a few hours relit pilot and system appeared to work normally.
Next day, boiler tripped again and noticed system pressure up to about 3 Bar, which is higher than normal. After a couple of hours, relit, however, very quickly water/CH was very hot (much hotter than normal), so shut down again and arranged local Worcester approved service engineer to attend, next day.
No evidence of safety relief having operated, no water at external outlet.
Service engineer attended and diagnosed expension vessel diaphragm gone, this presumably would explain the much higher pressure than normal (expansion vessel very heavy and full of water).
Service engineer advised replacement of expansion vessel and also possibly thermo couple and/or thyristor to solve overheating problem, advised parts should be available next day, but would confirm re-attendance to fit parts.
Got a phone call from the approved service agents later and was told that the reapir would be very expensive (about £500-£600) primarily because the expansion vessel is very difficult to access (strange as his service engineer had had the expansion vessel off earlier in day and it took 90 seconds), then advised as boiler 10 years old and inefficient (advised 60%) and likely to have further problems soon, best solution to replace with a new (guaranteed) boiler, advised that Worcester 4.5 would be best and very efficient (90%+)replacement (alarms bells here as at another family house I had a Worcester Highflow 4.5 fitted and that was before this 400 BF, so must be more than 10 years ago, estimated cost for new Worcester 4.5 is £2500 + VAT = £3000.
Having checked, it seems Worcester 4.5 is an obsolete model (although service agent said they have one in the showroom!) with an efficiency rating of 65% which is less than the actual 76% of my current 400 BF and it appears that direct replacement for my current model would be the Highflow 440.
As can be seen from above comments, although the service engineer attending appeared proficient, the approved service centre/showroom are a different matter.
Leaving aside the expansion vessel, which I can source and fit. What is the underlying cause(s) of the over heating, is it the thermocouple and/or thyristor as suggested by service engineer attending and what should I expect to pay to have one/other/both replaced?
Please note that the boiler is still functioning and heating water/central heating (only if I keep hot water running and open 5 large radiators as heat sinks to stop heat build up). Does the fact that hot water and central heating are being supplied concurrently mean that the diverter valve is malfunctioning (I was under the impression that when demanding hot water, central heating was not being supplied - which is I presume the job of the diverter valve), perhaps if temperature is enough, both are supplied, as is the case at the moment. If I shut down the hot water taps then water in central heating starts to get very hot (well, I can put my hand on radiators, but not for long), or much hotter than normal, at this point I shut down before tripping/damage.
Sorry for the long message, but hopefully the information contained therein will be sufficient for basic diagnosis.
I would appreciate advise on the above.#
Regards
