Worcester Heatslave 15 / 19 firing issue

[yorkshireman2013]

Hi there - hoping I can get some guidance on a bit of a weird issue we're having with our Worcester Bosch Heatslave 15 / 19.

After getting a host of problems (new PRV, new diverter) sorted last year, the boiler itself is working fine...sort of. The problem is that it isn't firing up on the programme properly - the CH won't fire up unless, while CH is set to be on, the HW is both fired up and turned off.

As an example, if I set CH to come on from 9.00 till 10.00 in the morning, it just won't. The light will come on, but the boiler won't fire up. The only way to get it to fire up is to set HW to come on at 9.10, and then go off at 9.20 - the CH won't come on at 9.10, but it will come on at 9.20 when the HW goes off. Or, as has just been the case, the HW light was on and the CH light was off. I advance the CH and nothing happens - until I then unadvance the HW, at which point the CH kicks into life.

Any thoughts or suggestions anyone can provide will be much appreciated!

 

[oilhead]

Do you have the built in programmer or is a remote unit?

 

[Boilerman2]

The built-in programmer on the H/S is made by ACL not a great piece of kit IMHO very likely to be a programmer fault

 

[yorkshireman2013]

We've got the built-in programmer that comes with the unit, not a remote one.

 

[oilhead]

If you are competent electrically, remove the top of the control panel and following the wiring diagram, check the outputs from the programmer into the PCB. Your symptoms would appear to a programmer fault, but there could be a fault in the main PCB or the diverter valve.

 

[yorkshireman2013]

I think it's fair to say that my electrical competence starts and ends with wiring a plug!

A new diverter valve was one of the issues we had fixed last year (previously enabling either the HW or the CH meant that both would come on regardless of which we actually asked for). That's no longer an issue - it's simply that when set on a programme it will not fire up until we then manually advance and then de-advance the HW.

Thank you for the suggestions, though - will get someone out with a programmer fault as their first stop.