I keep reading bits of this.
One thing that strikes me, before this system was installed, there was no "central" heating. Presumably fireplaces and plug in electrtic heaters used sparingly?
With the installation of this system, she suddenly, for the first time, has whole house central heating.
So even with the most efficient system on the planet, it is going to cost more to heat.
You still can't hide the fact that it's an ASHP, so even if it's being forced to work at a high temperature, so poor COP, it is STILL going to be cheaper than direct electric heating. and her only alternatives were oil, no mains gas there.
I think half the "problem" is she was not expecting (nor can afford) the cost of whole house heating for an old, leaky, poorly insulated house.
Also, she has economy 10. So for 10 hours out of 24, the electricity will be much cheaper (but it WILL be more expensive at other times)
I have not seen mention of whether she is using that properly. It wants to be on a timer to come on during the off peak periods to charge a decent size thermal store. Then ONLY come on at other times if the thermal store is severely depleted. That probably needs a custom designed control system with a lower limit thermostat on the store to override the controls and bring the ASHP on if the store is getting really cold. I'll bet it has nothing like that.
In the absence of any special controls to maximise usage in the off peak times, it actually may well be cheaper if she ditched the off peak tarrif in order to get a cheaper daytime rate, if it in fact turns out most of her usage is in the daytime.
Green Schemes - Handle With Care.
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