Worcester Bosch 24i (old style pre 2004)

[MrB]

I've just fitted a new PCB to a 24i. The hot water is coming on fine but not the heating.

I do not have a room thermostat rather a mechanical timer. When the programmer is set to constant and the temperature dial is rotated off the off mark, the heating burners do not kick in - the fan runs though and it appears that the pump runs.

The key may be in the fact that if I turn on the hot water whilst the heating is on demand, the burners kick into life and deliver hot water, but when the hot water is shut off the burners stay on and deliver heating.

The only other thing I've noticed is when the heating has been on demand (with not flame) it sometimes, randomly, starts up.

I've checked the wiring on the PCB at X2 and the link is in the room thermostat positions and the Neutral, switched live and live are in the correct positions.

This is not the same problem that lead to the PCB being replaced. That was a general fault (probably old solder) that meant you had to knock the boiler casing to get anything to work.

Any thoughts

Regards

 

[Billy Bob Bob]

are you a gsr engineer or competent sparky?

 

[MrB]

Competent sparks & plumber. Plenty of experience with 24i, 24cdi, and 28cdi I've owned. Replaced plenty of parts except gas, which I get an engineer in to do.

 

[Billy Bob Bob]

tried bridgeing the clock?

 

[MrB]

No. The boiler is at my office, so I'll try it possibly tomorrow or on Monday. I'm replacing the timer on Tuesday with a digital unit. The old one is fairly new but it's crazy for the heating to run Sat and Sun when I'm not there.

Thanks for your responses.

Regards

 

[diesel_ltd]

have you checked the ch thermostat? just a suggestion

 

[Puddle]

I would double check pcb conections and any jumper settings on pcb

 

[kaz786]

hi all....

i have a 24i pre 2004 combi boiler. i have the old style controls and want to upgrade to the digital controls.

Can anyone tell me where to get this from n is it just a straight swap for the old control unit????

Please advise, many thanks in advance...!!!