DIYbanter - View Single Post - Central heating a hot water system question

Jon

declared for all the world to hear...
The message
from Jon contains these words:

Are you sure that the absence of 'click' with the thermostat is it not
turning on? Given the symptoms it seems more likely that the thermostat
is not turning off. This is easily checked by disconnecting the
thermostat (after isolating the supply).

No, it clicks fine when the temperature of the room it is in is lower.
On this particular day it was very hot, and I wanted some hot water for
a shower, washing up etc. We had both the hot water and the heating set
to OFF on the programmer as it had been a prolonged hot spell. I pressed
the +1 hour button on the hot water side of the programmer and within
about 10-15 minutes the radiators were on full blast, even though we had
turned the stat down to 10.

As I missed the earlier part of the thread I may be covering old ground
but if the boiler is not responding to the thermostat something must be
shorting it out. I don't know whether you have 2 port or 3 port valve
control but I would have thought sticking valves and/or valve
microswitches need investigating next.

Sorry but I will be off-line for the next few days so won't be able to
take this conversation any further.

Cheers for the input. I've booked a boiler service and motorised valve
inspection for the next few days. Get it sorted once and for all.
--
Regards
Jon