Hi,

I have an optima 2 plus alarm system, and I have installed a new heating system.

I want the heating to operate according to one scheme when the alarm is set, but to a different scheme when the alarm is unset.

To achieve this I have bought two room thermostats, a heatmiser dt (a basic thermostat so i can set a low temperature for when the house is empty (alarm set condition)), and i have also bought a heatmiser prt (a programmable thermostat which i want to be in use when the house is occupied (alarm unset condition))

the wiring diagram for the basic thermostat is in this pdf file page 17 http://www.heatmiser.co.uk/manual/dt/dt_manual.pdf

and the wiring diagram for the programmable thermostat is in the same file page 20.

Is it possible to get the alarm system to switch between using one or the other thermostat , perhaps by switching between the live return outputs from the the thermostats to the boiler? could this be achieved with the current alarm system?

Yes, there is a set output (+ve I think) that could be used to control an octal relay.