air source heat pump in snow

Caernarfon 18kW Air Source Heat Pump Review – Autumn

Our Caernarfon air source heat pump has now been operational since the spring. It’s time to see how it performed over the course of the past three months as part of our autumn air source heat pump review.

To this point, our air source heat pump has had it easy and has been covered in our summer review.

To see how it performed over the autumn, including a very cold November, please check out this video.

Caernarfon air source heat pump review

For detailed information, please see the breakdown of our running costs below for September, October and November 2019.

Numbers for Sep, Oct, Nov 2019
Solar energy produced1.152MW
Total electricity used (after solar) 2,787mW
Electricity used by ASHP2,164mW
Coefficient of performance (COP)2.5
Electricity cost for ASHP£298
Oil cost in Sep, Oct and Nov 2018£750

Based on our electricity tariff, we spent £298 on heating over the past quarter, which equates to just under £100 per month.

We hope you enjoyed this review, and if you’d like to get informed when our winter update is out, please subscribe to our blog and YouTube channel.

6 thoughts on “Caernarfon 18kW Air Source Heat Pump Review – Autumn”

  1. Hi. After watching your last video I had an idea how to solve the problem with those rooms that stay cold.

    Put your thermostat that controls the radiator zone into the coldest room. Turn the radiator into full position. Then have all the others rooms set to desired temperature with the thermoststic valve on the radiators. When those rooms warm up the valve shuts off and hot water will only flow into the rooms that are still cold, until the coldest room is up to temperature and then the room thermostat will shut it and the ASHP off.
    I hope this helps.

  2. Thanks for the suggestion Andris. I’ve tried what you said, to no avail. The amount of hot water to the coldest room is not sufficient. It’s the only room in the entire house that we can’t get to temperature.

    I also removed our smart TRV and replaced it with a conventional one hoping that it would allow for more flow. It didn’t change anything. The temperature was exactly the same.

    1. In another perplexing twist, it’s been colder outside than on any other day this week and we’ve not tampered with any settings or valves. Incredibly, the water is flowing through the rad in the coldest room like a raging torrent and the room is up to temperature. It’ll be interesting to see if this maintains or whether it stops as abruptly as it starting working.

  3. Insightful content on ASHP – thanks. I am trying to work out what would be best for my home, which is also a large-ish detached rural dwelling that is heated by oil.

    It would be good to understand a bit more detail on your home – specifically the fabric, what work you did prior to going for a heat pump. The ‘fabric first’ mantra is great, but we don’t have the option to retro-fit all rooms in one go!

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