Vaillant Central Heating problem

[mwerty]

Hi there

I have a Vaillant TurboMax plus 824 Diplomat - it is about 4 years old now. At the moment I am having a problem with getting the Central heating to come on. The boiler ignites fine with demand for HW, however it nearly always goes to a lock out with F.28 when trying to fire for CH demand. Ocassionaly, if the HW has been on and the CH is called for, it will go to F.22. It nearly always fails to ignite for CH. If it put it in SFH mode (chimney sweep mode) it works perfectly.

A little history: previously neither the CH or HW was working: the boiler wouldn't ignite and kept going to F.28 and locking out. Engineer came, pressed some buttons and it worked fine until a week after he had left - I wonder if he just put it in SFH mode??

Any suggestions from anyone would be incredibly appreciated

Thanks all

 

[Deleted member 105431]

sfh only lasts 10 minutes before automatic reset. Sounds like you need an new gas valve and the ntc's checking. Vaillant would be your best bet 01773 828100

 

[mwerty]

Hi dangermouse thanks for your reply. is there any reason it works with HW but not CH? If i persist with the CH (by pressing reset button about 5 times after it has locked out after 3 times) it will sometimes come on: is it advisable to keep resetting it from tis F.28 lockout?

Thanks

 

[gas4you]

Perhaps a good service would sort it out. Could be the minimum burner pressure has dropped out of adjustment and/or the flame detection electrode needs adjusting nearer the burner.

Had this same fault last Friday.

When on for HW the boiler is demanding a higher gas rate so the above problem may not show until ch is on.

 

[Deleted member 105431]

Hi dangermouse thanks for your reply. is there any reason it works with HW but not CH? If i persist with the CH (by pressing reset button about 5 times after it has locked out after 3 times) it will sometimes come on: is it advisable to keep resetting it from tis F.28 lockout?

Thanks

F28 is ignition lockout and could be a number of reasons (electrode, ht lead, meter guvenor sticking, copper sulphide blockage, sticking/incorrectly set gas valve, faulty gas valve solenoid, low water pressure switch interupts electrical supply to gas valve on late production models, dirty injectors especially on lpg, dirty burner, polarity reversed etc etc). Job for an rgi.

 

[Gasguru]

CH is probably range rated to the minimum but may start from minimum and ramp up slowly; DHW ramps up to maximum quickly ensuring rapid ignition.

Call in a corgi to check the minimum burner pressure...you normally have to increase it a little from the book value. Also check flue restrictors (again the manufacturers instructions are incorrect).

F22 can be due to poor radiator balancing (see FAQs), thermistors or early pcbs. Common problem along with all the other design faults on this model.

 

[mwerty]

Is it unacceptable to simply use the chimney sweep mode to get the CH going?

Thanks for everyone's help and swift replies!!

 

[Deleted member 105431]

Is it unacceptable to simply use the chimney sweep mode to get the CH going?

Thanks for everyone's help and swift replies!!

it won't do any harm but will only last 10 mins.