28 July

It’s fascinating to experiment with this stuff. On a sub-zero night, I run the reverse-cycle units (heat pumps) all night, because as you can see they use only trickle amounts of energy to keep the rooms at temperature, that were heated during the day. In an 8-hour period overnight, they use about 5kWh of energy. If I turn them off before bed, and back on on a freezing morning, their draw jumps to 6-8 kW, to raise the room temperatures, with the heat pump outside having to work much harder against the sub-zero temps. The units are running 24 hours on those days, but it probably creates less wear and tear than a morning-only surging blast, which makes them work a lot harder.