Heat Pumps are like EVs, people hate them without knowing about them.
My electricity cost for November was £175. I am on the Go tariff so 4 hours a night it works hard and the rest of the day runs as needed. 250 litres of hot water and the underfloor heating of a 40 sq m kitchen are run at night time. April to September I doubt we will need to run heating in the daytime, the bill will be £65/70 per month for heat, light, cooking and motoring! November was pretty chilly so at the top end of consumption. December will be cheap, I am in Canada! But mine was installed in September and is missing some controls still, consequently I would expect bills to be reduced in any event. I used to use oil buying around 2,200 litres a year, so consumption about 2,000 kWh. This year oil would have been £1100, I estimate that will be more than my full electricity bill.
Now my house is 5 beds, 3 bathrooms large lounge and larger kitchen, in the open plan style. Most homes won’t need a 14 KW heat pump (Ecodan) and the smaller units are 10% more efficient than mine. Big radiators are a must but my house, originally built in 1984, extended in 2017, was built with single glazing and little loft insulation. Bringing it up to date with cavity insulation and loft insulation and double glazing meant that all but one radiator needed changing, and that was a simple swap of a single panel for a double.
The installation looks more complicated than it really is, now that I have seen it done I would be tempted to fit one myself in the future. The smoke and mirrors are about getting a high volume of water round so that the temperature drop across the radiator is only 2~3 degrees and the heat pump output is as low a temperature as possible, 30 to 35 degrees will produce a very cost efficient system with a COP of 4 across the year. It might be advantageous to use an under sink water heater in the kitchen, bathing water is cooler and within a more efficient range of the heat pump and you don’t have to waste water running the tap waiting for hot water to reach it.
We have 3 circulating pumps now and you need a mass of water in the system to stop the heat pump cycling, big heat pumps of 8.5 kw and above need 28 mm pipe work, you also need a hwc with a large coil/heat exchanger. But for a regular 3 bedroom semi, I think a 5 KW pump with a conventional 165 litre part L hwc, 22 mm pipe work and 1 circulating pump for 8 radiators would do it. Even if you added just one night storage heater as back up where the heat loss calculations are borderline that would be a rational and inexpensive way to do it. PM me if you want full reasoning.
