Air Source Heat Pump Advice

Try turning the flow temp down until the place is comfortable - it took me a whole winter to get mine tweaked. My heat curve goes from 40 degrees at zero outside to 25 degrees when it's 15 outside but we've got u/f heating.

How is the heatpump controlled - has it got a room stat, where is it situated. Does it turn the pump on & off. How is the system configured, do you have a buffer tank.

As I understand our system, the central circuit heats up even if no heating is required - the themostats only control the valves off that heated circuit. And the thermostats themselves appear to be far less precise than we were told by the installer.

I'd be very inclined to get a programmable wireless thermostat then you could locate it in the best place to suit your heating & lifestyle.By the front door is never a good place for a thermostat

As said before turn the flow temperature down a few degrees and see how it works out. keep tweaking it down until it's not hot enough or doesn't heat the place fast enough and then turn it up a bit.

Most heatpumps are spec'd at a flow temp of 35 degrees when it's 7 degrees outside so if it's colder outside or your flow temperature is higher than then efficiency will suffer and cost will increase.

We dont have a buffer tank so the heatpump works like a conventional boiler, feeding a diverter valve, either to heating or the hot water tank.

Because we've got zoned u/f heating we have eight programmable stats each of which switch on the heating and circulating pump and open the flow valves on the appropriate zone. We dont let the house get cold - the stats just back off the temperature to around 17 degrees otherwise it takes too long for the temperatures to recover. This time of the year the heating will sometimes run all night.

You could try running yours for a bit longer at a lower temperature and monitoring your energy consumption to see how it gets affected. Get an energy monitor to see whats happening and when, like this https://www.energyhive.com/dashboard/dave

We only heat our hot water to 45 degrees for an hour or so a day which we find is hot enough and sufficient for our needs. It boosts up to 60 degrees once a week to sterilse the tank.

The other thing that bashes your bills is using the back-up heater or boost heater. Most heatpumps wont push the temperature above 50-55 degrees so it you want water hooter than that then an immersion heater of some sort kicks in.

Do you have yours on an E7 or single rate tariff - mine is on a single rate because it runs virtually all the time, I've no experience of a system with a buffer tank so I dont know how much heat storage you've got to make an E7 tarrif work effectively. Perhaps others could advise

mains gas central heating is cheaper to run and more responsive than any sort of electric heating including heatpumps so I wouldn't be tempted or persuaded to install a heatpump if I had gas. 

Regarding your friend, thats a decision that only she can make. As you say they are expensive to install especially if she has to have a complete installation. They can be more economical to run than storage heaters BUT and it's a big but, the system has to be designed correctly, installed and set up correctly and most important of all used correctly. Beacuse they run at low temperatures, they need to be on longer, they dont heat the place as fast as a conventional boiler, they need larger radiators with lower flow temperatures and ideally you need lower hot water temperatures. Many people are unhappy with them for that very reason and so crank them up which significantly increases their running costs.

We've had ours for ten years and it works for us and i reckon it's paid for it'self in that time both in lower heating bills and because we get RHI payments totalling around £5k. but we've learned how to use it properly and we've got reasonable insulation.