I'm now in 4th gear with power to spare!
Join Date: Jul 2016
Location: Lancashire. UK
Depends on how you configure the heater. For use a supplementary heater it is just plumbed into the coolant system. It can either be activated remotely to heat up the engine before you want to use the truck, either via a manual switch, RF remote control, or a timer, similar to a central heating timer.
Another method of activation, used on the Rover 75 is with an ignition on signal fed via a 5 degree thermal switch, sensing ambient temperature, so on cold days, the heater kicks in once the truck is started, and this speeds up engine warm up.
They can also be used as auxiliary heaters whereby an output from the heater is used to wake up the trucks aircon panel once the coolant is up to temperature, In order to do this a tapping is required into the aircon panel so it is possible to energise it via a relay with the ignition switched off.
2003 D22 Outlaw with added blackness