The units I've tried out always run as default in cooling mode. You need to energise the 4-way valve solenoid for it to work in heating mode. On my unit I simply do this by connecting it in parallel with the power input. My units are either on or off so the solenoid gets time to energise to reverse the flow before the compressor has started up. It's a bit 'odd' when it shuts down, makes strange noises as the solenoid de-energises and the refrigerant flows back the other way causing a quick burst of cooling.
I thought about the possible problems this might cause but the unit must be designed to cope with this as it is exactly what would occur in a power outage.
Nigel
|