In August 2022, we moved into our new two-bedroom house in Pembrokeshire. The bungalow, originally built sometime in the 1800s, was of solid stone construction. It had been extended in the 1970s with a new kitchen and front room featuring double breeze block construction with loose-fill insulation. The EPC was an optimistic C, but it did have 2.66 kW of solar panels on the highest FIT tariff.

I had installed a 5 kW Mitsubishi Ecodan ASHP in my previous house, a self-build from 2012, and wanted to use a heat pump again in this one. This property currently had a quite nice, newish gas combi boiler, but I knew I could reuse it in a rental property I owned.

I had been happy with the Mitsubishi and considered purchasing one again, but was tempted by the cheaper, newer, higher-temperature Samsung Gen 6, which I had heard good things about and seen that the controller was easier to set up. It also had some interesting communication options via Modbus.

I considered applying for the government grant, but for various reasons, decided to install it myself. It would be cheaper that way, and I was confident that I could do a better job than many of the installs I saw complaints about.

In preparation for the heat pump, I beefed up my loft insulation and ran my gas boiler at a low temperature to see where I needed radiator upgrades. I was able to shuffle radiators about to smaller bedrooms, purchasing only two very large radiators for the living areas. I also fitted a Mixergy hot water cylinder and MyEnergi Eddi solar diverter to enable us to have hot water once the gas combi was removed.

In February 2023, I bit the bullet and ordered my Samsung 5kw R32 Monobloc Gen 6 heat pump from The Heat Pump Warehouse. It arrived as promised, and I set about installing it with the help of some YouTube videos. In my previous house, I was frustrated that I could not monitor how my heat pump was performing, so I decided to stump up for an OpenEnergyMonitor system that would do the job.

Installation went relatively smoothly until it was time to switch it on. At this point, an error code popped up. After much frustration and fault-finding on a Sunday, I found the problem. The fan hadn't been plugged into the main circuit board. Needless to say, I was a bit miffed about this and later discovered that the heat pump had, in fact, been supplied by Joule, who denied all responsibility for the fault and even went so far as to accuse me of sabotaging it myself.

I encountered some other issues along the way, and these are described fully in my blog, The Greening of Rose Cottage, for those interested. The Samsung controller was used as the only thermostat for the system.

Once the heat pump was up and running, I set about adjusting the weather compensation settings to give us the appropriate heating temperature. We prefer 22C in the living rooms and cooler in the bedrooms. All thermostatic radiator valves were opened to their maximum, and the manual radiator valves were used to adjust flow. Further adjustments were made as the outside temperatures got colder later in the year. We tend only to heat the house during daytime hours.

The heat pump performed well, with heating SCOPs between 4.65 in September to 3.97 in December. After purchasing an electric vehicle and moving to the Intelligent Octopus tariff, I made the decision just to heat the water cylinder via the immersion heater at night for 7.5p/kWh and not to purchase a heat exchanger to enable it to be heated via the heat pump.

To complement the heat pump, I had an additional 4.65 kW of solar panels fitted, along with a 5kWh battery. This helps keep the electricity costs down greatly, and so far, bills have been lower than they would have been had we still been using gas. I expect to see a significant income from export in the summer months to help offset the costs of the improvements.