Michael_S

IS it not possible to get 15kwh of battery for £1500 and £500 for an invertor? - that electricity can then give you 45kwh during the day from your heat pump?

There seems to be an odd puritanism with regards to AC. It is apparently fine not to want to feel too cold but want to not feel to hot and you are a selfish climate wrecker.

People chose to invest in a potentially risky new technology based on and agreed set of returns. Which other contacts should the govt renege on? I am a civil servant, you probably think I am overpaid and the government should unilaterally cut my salary including for the work I have already done this month?

Logically I think you are right but in reality people seem to be very short-sighted and only look at the up front cost - se for example EVs.

We had a weather comp boiler that modulated down to under 2kw and heated 24/7 with night time set back, the curve went to about 55 flow at -10 when it ran at about 7.5kw constant. WE had hot water tank in the loft so only needed a 18kw boiler which gave the good modulation. Funnily enough now with an oversized heat pump and a heat demand when it is mild of about 1-2kw we get a lot more cycling than we did with the boiler....

EVDB says 165 winter, 210 summer at 70mph. IMHO if you have home charging then the range number that matters is range while travelling at long distance journey speeds, being able to get 240 around town makes no odds.

So if it takes 2kwh of gas to generate 1kwh of electricity at the home (60% efficiency, transmission losses), then how come that kwh of electricity does not cost about twice what a kwh of gas does - we need some allowance for the cost of the gas-fired power station but I believe this is not huge on a per unit basis and perhaps the electricity transmission grid costs more per unit than gas transmission? - but still doesn't explain why electricity is more like 4x the cost of gas? So here is a suggestion. Given heat pumps give 50% more heat output per unit of gas (50% loss in generation and transmission but 3x gain in COP) why not have a heat pump meter and charge electric units used by the heat pump at 2x the cost of a gas unit (and build the necessary gas generation to support this knowing that by speeding up heat pump roll out we are reducing our carbon footprint)

Depends a bit how efficient you think a gas boiler is in terms of KWH of gas per kwh of heat.

Depends a bit how efficient you think a gas boiler is in terms of KWH of gas per kwh of heat.

WE have a series 2 and don't think we have this option unfortunately as it sounds really useful.

Works for us with a home made install, second hand 10 year old heat pump connected to the tails of a radiator running through undersized circulation loop and immersion hot water - but of course we have a big battery (60kwh via V2H) and a 6.7p overnight tariff so a cop of 3 for heating (and 1 for hot water) doesn't matter. Total cost was about £600 but spent another £1000 this summer upgrading 7 radiators to allow lower flow temp, would have been cheaper but 5 are designer ones.

May be the thought is the extra energy in the volumiser will give the heating a boost when switching back after a hot water cycle and the house possibly having cooled? I think I read somewhere that plastic pipe is less 'smooth' when it comes to flow so 26mm internal diameter plastic has more resistance than the same for copper (plus it may have inserts in the joints?) The 860 number quoted above is a useful rule of thumb.

You are doing well to even find out how much most heat pumps on the market modulate, most manufacturers seem to keep this info very close to their chests.

The only advantage for me is that should you get that long power cut or a system failure you don't have to drain the HP to protect it. Downside of course is the reduced efficiency in heat transfer. We are running a second circ pump (due to undersized pipes) so it is only the prolonged power cut that might cause us a problem whereas adding gylcol would definitely result in a reduced heat transfer rate problem.

Could it relate to over voltage in the mains? We have a wifi enabled RCBO on our HP so can see real time the voltage, current, watts, leakage, cable temp etc.