Honeywell (ST699B1002) programmer problem

[cazzer1]

Just thought i'd check the wider community for some advice before i spend money unwisely.

My gas central heating system has been running faultless for over 3 years using a ST699B1002 control unit for the water and heating.

Within the last 48 hours the hot water timer section in the control unit has failed to come on at the preset times. I've tried resetting and changing the times etc, but it appears completely lifeless. The boiler is good and I can get hot water through my radiators as heating timer section of the unit works just fine.

Has anyone experienced this kind of problem, where the heating timer works ok but the water appears dead?

I have looked at the wiring diagram for this unit and there only appears to be one fuse and i'm assuming if that had blown, the heating would be out aswell.

If it is the unit, then I can only check the obvious stuff with the cover removed.

Grateful for any feedback.

Paul.

 

[ollski]

If the red light comes on the timer my guess would be that you have two motorized valves in the airing cupboard (or somewhere), the hot water one of which is causing you a problem. If the light doesn't come on swap the 699 out for a new one at about 40 quid from screwfix.

 

[Joe4542]

Hi Paul,
Do you have any knowledge/experience of electrics?

If so you could check to see if the programmer is giving a output (240V) on programmer pin 6 (HW ON) - if it isn't, then providing there is 240V at pin 8 - the internal relay has died...
If there is an output on pin 6 - then subject to your heating system - you may have a fault with a zone/motorised valve.

If you don't know what you're doing with the electrics - then it may be engineer time...

Hope that helps!

Joe

 

[cazzer1]

Thanks for replies.

I will test the contacts suggested.
For the sake of £40 i'll get a new unit anyway, else it could cost me £100 to be told that!

At least i'll know its not the unit if i just remove old and replace like for like.

Paul