Semi-detached property, hosted by Nick

Ours is a 1902 built house with cavity walls downstairs, solid brick upstairs, the house was doubled in size in 1993. The cavity walls are insulated and there is ample insulation in the two loft areas. Total floor area 150 square metres, heating supplied by 15mm pipework to radiators.
We have 11 solar PV panels (ESE facing) on the front of our property and 11 panels (WNW facing - installed May '25) on the rear (a total of 9.3kW) and 12kW battery storage and 180L hot water cylinder with iBoost (immersion).
The Octopus installed ASHP (Daikin Altherma 3 Monobloc - 11kW) replaced our 30-year-old gas fired Rayburn cooker and back boiler, we now have no gas to the property, cooking is by an electric oven and an induction hob. We are currently on the Octopus Cosy tariff so that (particularly in winter months) we can charge the batteries with cheap rate electricity between 04:00-07:00, 13:00-16:00 and 22:00-00:00 resulting in our average unit cost of electricity taken from the grid over the winter months being less than 15p per unit. We earn 15p per unit on everything we export to the grid and over a year we now generate as much as we consume.

Installation took place in the last week of October ‘23 over five days. The Octopus installers were very friendly and took great care of our property throughout covering carpets and wood flooring with strong plastic sheeting or absorbent rubber backed matting. Octopus gifted us a fan heater for the few days when we were without heating and would have provided more heaters if necessary. We were without hot water for less than two full days.
Several radiators were replaced but generally by deeper radiators, triples (K3) replacing doubles (K2), or doubles (K2) replacing singles (K1). We had an additional large vertical radiator and pipework plumbed to our garden room (tiled roofed conservatory) which was previously unheated and therefore not used in the winter months. We now use it year-round.
The hot water cylinder, expansion vessel & buffer cylinder were sited in what was our bathroom airing cupboard, replacing the old hot water cylinder. The cold-water tank and hot-water header tank were removed from our loft. 

Inevitably we had some slight anxieties around the installation; would the house be warm enough with the ASHP running at a lower temperature than our old gas back-boiler and how noisy would it be? We are very happy that neither are issues.

Yes, the heat pump is a large piece of kit, and my wife was a bit taken aback when she saw it unpacked, but the lead engineer said that if this was an issue that it could be sighted somewhere further up the garden. As you can see from the photo, we went along with the original suggestion.

It generally runs very quietly, hardly noticeable when standing outside even when the air temperature is around 4 or 5 degrees. When the temperature gets to be around freezing (or just a degree or so above) or when it first turns on it pumps the water at a higher rate and the fan turns faster so that it makes a little more noise but even then, we cannot hear it from inside the house at the nearest window. One day last February when the temperature dropped to -6 it did have to work harder and made a bit more noise so that it could be heard in the kitchen but not greatly and certainly not an issue.

Regarding the temperature within the house, it did take a little while to adjust to living with the new system. The most noticeable difference is that the radiators are never hot, they are warm and sometimes not very warm at all and it’s amazing that the room temperature is perfectly OK.
We are retired so one or other of us (or both) is usually around for any part of the day.
Our schedule is to have the thermostat set at 19 degrees throughout rising to 20 degrees between 15:00 and 21:00 to make sure the lounge is at it’s warmest in the evening when we are less active.
I have tried keeping it set at 19 throughout but because the temperature fluctuates between 18.5 and 19.5, if it happens to fall to 18.5 while we are watching TV it can feel not quite warm enough. I have tried setting it at 20 throughout (ranging between 19.5 & 20.5) but this feels unnecessarily warm at times. I’m talking minor adjustments here, even at 20 throughout our heating costs would be much lower than before. And, apart from this initial tweaking we don’t touch the thermostat (or App), it runs in the background and looks after itself and us.
We do switch to an “Away” schedule of 18 degrees throughout if we go away (which is never more than a week at a time) so that the house doesn’t cool down too much.

The ASHP is set to heat up hot water at 04:00 and again at 13:00 (if necessary) when our electricity is cheapest (water is usually heated by Solar in the summer months). We generally use between 1 & 2 kWh of hot water a day. There is always plenty of hot water. It was initially setup to heat to 50 degrees, but we have found that 45 degrees is perfectly adequate and as a result the system runs more efficiently.