Ideal boiler slow to initiate

[Bosbarn]

Hi.

Have an Ideal condensing boiler, water and central heating.

When heating is selected can take up to 15 minutes at times before it tries to ignite even when the boiler has not been on for 8 hours and the system is cold, when selecting hot water it always fires up straight away.

Have a Honeywell HCW80 wireless room stat, new batteries, and when I turn the stat up and the red light comes on on the stat, the boiler does not try to light for usually 5 - 15 minutes.

Programmer is a Honeywell ST9400C.

Any ideas appreciated as to why it should take this long to come on when heating is called for, used to fire up straight away.

Thanks.

 

[picasso]

If the boiler is starting without any delay on hot water then the fault will be either the stat or motorised valve on the central heating.

 

[Bosbarn]

Thanks for your reply.

 

[MeldrewsMate]

As @picasso said...I'd opt for a zone valve fault, end switch or slow opening.
Turn just the heating on and its thermostat up, then use the manual lever on the 2/3 port valve to help it open. Does the boiler fire-up immediately now?
When you turn the roomstat down can you hear the zone valve spring returning with a 'whizzing' sound?

 

[ianmcd]

+1 for a lazy synchron motor on your heating zone valve

 

[Bosbarn]

Just an update.

Replaced the motorised head and all is back to normal.

On closer inspection of the old unit and using the manual lever, the pinion on the motor and the quadrant gear seemed to be jumping across the teeth more often than not.

Thanks chaps.