Air-Source Heat Pump

Regular readers will know that I installed a Smart Switch with which to remotely control my Air-Source Heat Pump, so I could switch it on under varying circumstances, such as, between 12 and 1pm on a sunny day, taking advantage of free solar PV to heat the domestic hot water.

Well, the switch being in the engine room, I had a helluva job getting it to connect to the house Wi-Fi and it kept dropping the connection. Even a repeater wouldn't facilitate a reliable connection. I eventually gave up and resorted to manual control, but had to be home to switch it on.

However, I remembered I had a Vodafone Mi-Fi dongle that I'd given to No.2 Son for use at university. He told me he hardly ever used it, so I repatriated it. I discovered that the SIM had been cancelled in April, although I don't remember cancelling it, but I did have a review of all my various mobile and broadband contracts in April, so it may have been cancelled accidentally.

Anyway, I resurrected it with the cheapest data-only SIM contract I could find, at £8.50 a month for 4Gb, and connected the ASHP to it. Works a treat on Tuya and I now have full, remote control of it again, wherever I happen to be.

Switching it on for an hour at midday on a sunny day enables me to heat the water to 60 degrees, which will retain enough heat to have a hot shower the next morning - and it's free through the solar PV. Of course, I can only do that on sunny days, but the fact I get free electricity even on dull days means I still save some money on whatever I use.

I'm always tempted to switch it on before 12:00 on really sunny days, but it would be a waste of money, as the solar thermal takes the initial strain, so leaving it till 12:00 (13:00 in summer) reduces any potential bill if it's partially cloudy.

When away, the automation feature can be a bit iffy, as the light sensor I use isn't granular enough and can switch the ASHP on even when quite cloudy, or off if a cloud blocks the sun. With a 1 minute starting cycle, just a few clouds in the sky can result in it never switching full on.

To overcome this I've ordered a couple of Smart CCTV cameras which will be trained on the sky, allowing a bit more subjectivity (but not automation). I can simply check the CCTV cameras when away and make a decision as to whether to switch the ASHP on remotely or not.