You are the one confusing things. You are confusing my peak heat load with your average electricity consumption. Are you trying to confuse the people reading this who might be trying to make an important investment decision on their house? I can assure you that I am not trying to confuse anyone. But thank you for confirming my estimates of your system and its performance.
AIC wrote:And that indicates an average heat load of 1.5 kW. The average CoP (I have a heat output meter fitted - but I don't hold too much store as to its accuracy as flow measurements are notoriously difficult to do accurately, esp.if you want them cheap) is 3. So that might imply that the house heat load is ~ 4.5 kW
You can't have two average heat loads. You have an average electricity use of 1.5kW indicating an average heat load of 4.5kW with a peak load of 8kW. That would give a peak electricity demand for heating alone of about 3.2kW when the COP is 2.5. So last December you were using 3.2kW of electricity continuously for about three weeks. If you fitted a heating system to deal with an average heat load you would spend much of the year with a very cold, uncomfortable house.
So looking at your installation, not only did you have the cost of the heat pump, you had the cost of installing larger radiators and a larger area of collector. Make a note of that if you are looking at an installation quote from a heat pump salesman now. Does the quote include those extra costs? You are also in the fortunate position of owning a large area of land with a high and moving water table which means that your heat source is conveniently replenished. Even so your COP goes down to 2.5. What COP is your heat pump salesman quoting? Without the benefit of a moving water table most peoples COP could well go down to below 2 for late winter/early spring when the heat is needed most.
I agree with you on the Legionella point.
Regarding Armageddon, I think it would be sensible to plan for a crash worse than the 1930s. Mervin King, the Governor of the Bank of England, said that there is one on the way soon. If it's good enough for him, it's good enough for me. And remember that it took WW2 to get the world out of that recession.
Once again you mention that I specify insulation with no regard for cost. Builders have been telling me that for thirty five years. Clients, however, have been enjoying the comfort and savings bought about by insulating their homes to more than the economic thickness of the time. The 100mm of cavity wall insulation that was uneconomic in the 70s and 80s is now the requirement. The client who put 50mm of external insulation on there solid walls in the early 80's is now regretting that they didn't put more on back then because their savings would have been greater. It's the economics which are wrong not the insulation. In my lifetime the "economic" thickness of loft insulation has gone from 50mm to 100mm to 200mm to 270mm as fuel costs have risen. Are they suddenly going to stay the same?
The u-value for walls has gone from no requirement to 0.6 to 0.45 to 0.35 to 0.3 so why not just jump to 0.12 - 0.15 when you reach the point where reducing the heat loss any further is just not practical because the insulation thickness to increase the u-value by a significant amount then becomes so thick that the embodied energy in the insulation wouldn't be saved. There are limits, I do agree. At these limits a central heating system is not required. Most people would be saving 80% or more of their current heating bills.
The Green Deal is a good idea as far as it goes in allowing the insulation costs to be spread onto future owners who will also benefit from the insulation installation. But it doesn't allow for sufficient spending even though the government have admitted that fuel costs will continue to rise. As I have written elsewhere what is needed is a National Insulation Scheme instead of more Quantitative Easing paid for by the government printing money and taking it back over a long period. That would do more for the economy than putting more money into the banks.
