My heating system has suddenly developed a problem where I am unable to turn the heating on unless the hot water is on as well. I am unable to run just the heating on it's own. Should I change the timer unit or could there be another problem? Any info gratefully recieved!
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Honeywell ST699 faulty?
- Thread starter gunplumber
- Start date
Assuming you have an 's' plan with two twoport valves (somewhere between the boiler & the cylinder cup'd perhaps) check that the heating one is opening, it may have a manual opening lever on it which can be hooked in the fully open position. (having reread your post it may well be stuck in the fullly open position already....)
If the lever is seized or you can feeling it pulling against a spring check, you may have to replace the actuator head (the silver grey box)
The ST699 clock is generally bullet proof, the red LED alongside the heating slider should be illuminated when the clock is calling for heat, is it?
DH
BTW, which boiler do you have?
If the lever is seized or you can feeling it pulling against a spring check, you may have to replace the actuator head (the silver grey box)
The ST699 clock is generally bullet proof, the red LED alongside the heating slider should be illuminated when the clock is calling for heat, is it?
DH
BTW, which boiler do you have?
Thanks for your reply. Next to the tank in the airing cupboard there is something which has a square blue plastic cover and has 'mid position actuator' on it - I think that is what you are referring to but how can I check to see if it has a fault? There are no levers that I can see. Below that is what might be a pump with 'Grundfos' on it. (Looks like a small car starter motor!) The LED stays lit next to the slider and my boiler is a Potterton Flamingo 50s.
Have a goosey-gander at this, and let us know how you get on. I understand that the all blue cover type is a British Gas badged-up version of the Drayton MA1 type actuator.
DH
DH
There is a mention of British Gas on it. Was there a link on your post?
There was.
I thought.
Try this
http://www.diynot.com/forums/viewtopic.php?t=279450&start=0
If you use the search facility using MA1, or the BGMVSP as the key word, you'll find you're not the first, nor the last to have had 'issues' with this.
Best of British.
DH
I thought.
Try this
http://www.diynot.com/forums/viewtopic.php?t=279450&start=0
If you use the search facility using MA1, or the BGMVSP as the key word, you'll find you're not the first, nor the last to have had 'issues' with this.
Best of British.
DH
Thanks for your advice. Perhaps I should just change it for a new one!
Finally got around to replacing the actuator and the heating is working again. Not only did you save me a fortune but i've learnt something about central heating into the bargain. Many thanks once again DH, I owe you a drink! 
I'll be round in fifteen, £48 + the VAT for the diagnostics.... 
DH
DH
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