Boilers and hydronic heat systems can be set up in a variety of ways. From
your description, it sounds like your boiler and domestic hot water work
independently from the thermostat. The thermostat, in that case would just
be controlling circulation to the radiators. While dust can be a factor, my
guess is that the drilling severed conductors in the thermostat wiring





"David Hansen" wrote in message
...
On Tue, 22 Jan 2008 02:07:37 -0800 (PST) someone who may be
" wrote this:-

Boiler does start as per times set (Twice: once in morning and once in
evening, two hours each time). Water tank gives hot water. But all
radiators in the house are cold.

This began after holes were drilled right above Thermostat that
dropped lots of fine dust on Thermostat and surely quite some got in.

Possibly. It may be that the dust has formed an insulating layer on
the contacts of some types of thermostat or obstructing other bits
of the mechanism and is preventing the contacts closing.

If you know what you are doing, you may be able to turn off the
electricity and clean the mechanism. This should cure it.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54