I remember the winter of discontent and how cold I got with no heating as even with gas, still needed electric to run, so since then all homes have had either a gas or open fire for emergencies, and also an electric oil filled radiator.
Today I have 6 kW of solar panels, and a 3.2 kW battery, so with a power cut I stand a chance of keeping the central heating running, however today this
is my solar PV, and 485 Watt will not even keep back ground stuff running, never mind a heat pump. Here is total
for the day, yesterday was good day for solar, it peaked far higher
but still unlikely to power a heat pump for long. My battery will charge at 2 kW and discharge at 3 kW this is enough to span the peaks and troughs, but to store on good days and use on poor it would need to be 10 times that size, the idea is once a battery and solar are fitted, one can buy electric at a cheaper rate over night, so the battery can be topped up over night, and you can export during the day, so battery does not really need to be that big, it is a tick the box exercise.
The heat pump works better the less the differential is, so the radiators need to be larger for it to gain the maximum, and most homes have a 60 amp supply, it can go up to 100 amp, but my 19 kW oil boiler is over 80 amp at 230 volt, what we hope is as more efficient it does not need 19 kW may be a 1/3 of that, so 27 amp, however most the heat pumps are well below that.
However with gas or oil we can reduce the energy used by turning of the heating when not required, and by having a boiler over the size required to maintain the home, we can allow the home to cool while not being occupied, then reheat room by room as required, to maintain my house likely only requires half the size of boiler, so could maintain it with 14 amp, but then we are wasting power by heating rooms not occupied as we don't have the power to reheat them, only maintain them.
So step one must be to insulate the home, and reduce losses to a minimum, and once that is done the heat pump can maintain the home better. The gas, oil, solid fuel would also heat it for less money, so what you are looking at is the time the home is not heated, and how much the temperature drops during that time.
So over night my heating goes off at 15 minutes past midnight and comes on again at 8 am, the TRV in the living room actually records the temperature as a graph, so I have this
report, it was 11 am before the room had recovered, and one can see it cooled to around 15ºC. And one can also see how the hotter it was, the quicker the temperature decayed. So even if you only drop the temperature by a few degrees, you can save a lot of energy, I am not an early riser, so 11 am for me is fine. But using a heat pump it would double the recovery time so 2 pm before recovered, that is simply too long. However if I reduced losses by half then it would be a faster recovery, but so would the oil fired boiler, so could set it to start at 9:30 am instead of 8 am so I would save even more.
So what I am saying replace the 19 kW boiler with a 27 amp heat pump it may work, but what is being done, is the promotion sites are not comparing like with like, so for a retired couple it is possible the heat pump would work, however before I retired I did not want the house warm until 6 pm, and by 10:30 considering going to bed, so only want house warm for 4½ hours in every 24 hours, keeping the home warm for 19½ hours when not required because the heat pump is not big enough to reheat the home, is clearly not going to work.
So what we want is larger radiators (output wise, which is not the same as physical size) and a large boiler to quickly recover the home temperature within the time geofencing will have when it detects your returning home, at least for rooms you will use on arrival, so looking at ½ hour to reheat home, only way to do that is with fan assisted radiators, and when you look at it this is where the heat pump really comes into its own, as with fan assisted radiators it can both heat and cool the room, and if we are heading for globule warming we will need to cool the rooms in summer, so now we are talking, however two stumbling blocks, one is cost, the other is most heat pumps being installed will only heat the home, rather a blinked approach, seems governments don't really believe in globule warming or we would be fitting the reversible type, so it is just a way to generate jobs and get people to spend more money. It has nothing to do with globule warming or the pumps would be reversible.
