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Problem with central heating/hot water timer... please help?

Postby HelenaRose » Sat Dec 29, 2007 4:46 pm


We have a problem with our central heating (oil fired) which I hope someone can help with.

If we switch on the heating with our timer/programmer then the boiler sometimes (but not always) switches on; but the radiators do not get hot. The hot water works fine as far as we can tell.

Looking in the attic we found a small switch near the pump with two settings - Auto and Manual. If left on Auto then the problem above occurs. If we switch it to Manual then the radiators do come on. But next time we want the heating on, we find it doesn't work... go up to the loft and the switch is back to Auto again.

We wondered if the timer/programmer (a Danifloss CS715) was faulty so we replaced it with a Drayton Tempus 7 one. Looking at the wiring diagram that came with the new one it indicated that no wiring changes were needed; however we did notice that the black (neutral) wire that should have connected to the 'CH Off' terminal was instead connected to the same terminal as the neutral of the mains wire. So we made sure that when we put the new one on, we put this wire in the correct terminal as indicated on the instructions.

But, when we switched on the power we found that neither the hot water or the heating worked when you set them to On... nothing happened at all. So the black wire back in with the neutral of the mains wire it now works as it did before; i.e. only with the attic switch set to Manual. :(

Does anybody know what the problem is that we have? We only moved into this house in the summer so we are not very familiar with the whole system. We are completely confused and don't know where else to begin trying to figure out this problem.

Sorry if this problem/answer has been posted already- I have searched for it several times on here but couldn't find anything that matched this problem.
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Postby ericmark » Sun Jan 06, 2008 10:59 am

As an electrician I have only worked on gas systems but I am guessing the little switch may be on motorised valve. It is to allow bleeding of the system but if the microswitches inside the valve go than moving the switch can temp get it going there are Y and S plans Internet hunt may find these.
Not a simple if timer and thermostat on then heat also valve must have gone to central heating position as well. I expect oil is same as gas for this.

Postby htg engineer » Sun Jan 06, 2008 11:25 am

The switch from auto to manual - I take is on a acturator/motorised valve ? replace this valve and that should solve your problem.
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