honeywell problem

[tgs166507]

Hi
I've got a honeywell st699 timer (twin slide type) and a standard honeywell room thermostat. Whilst decorating, I niavely tried to fit a different thermostat and ended up blowing the fuse at the boiler a couple of times. Now I have a situation where there is a constant live feed to the room thermostat which allows the room thermostat to activate the boiler, even when the timer is off. This was not the case before I blew the fuses. From the various wiring diagrams I have, it would appear that there should not be a live feed to the room thermostat when the boiler timer is off. I have now fitted a new honeywell room thermostat which appears to work ok.
Can anyone advise on the likely reason for the room thermostat now governing? Have I fried the timer unit?

Thanks in advance.

 

[seco services]

how can you of fried the timer if you have fitted a new stat and its working ?
that proves the timer must be ok.

 

[simond]

I think this story has been told in a confusing way.

My reading of it is that when the stat was changed the boiler fuse popped a couple of times. Now another new stat has been fitted (another Honeywell) the stat works but the boiler can be turned on from it, irrespective of the settings on the timer.

If I have intepreted this rather ambiguous story correctly, you have welded on the relay contacts in the timer (due to the fault current when you short circuited it) and it is scrap.

It is worth tapping the relays with a large instrument to see if they will spring back, but this has only worked once for me........ otherwise, its a new timer.

 

[Softus]

Let me guess:

When you replaced the thermostat you connected it wrongly and blew the 3A fuse.

You replaced the 3A fuse with a 13A one, and damaged the programmer, probably fusing its relay contacts in the closed position.

Is this anywhere near the mark?


Edit: Oh bum - simond got in first.

 

[tgs166507]

sorry for the ambiguous post!

simon, you've got it right.

the timer appears to work, i.e. it responds to the on/off timer that I set, and the little LED lights up, but when the timer's off, the thermostat can bring the boiler on...

By the sounds of it Simon, I'd better fit a new timer.

Thank you both for your help.