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ASHP Boiler Replacement

edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
2 replies 1K views
Exiled_TykeExiled_Tyke Forumite
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edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
A (well known) energy company is trying to persuade me to replace my boiler with an ASHP claiming that it will save me money. Granted there is a government incentive that will offset some of the capital cost. But by my calculations it still does not stack up.

The ASHP is claimed to be on average 300% efficient. If I generously assume that my current gas boiler is only 80% efficient then, the ASHP is 3.75 times more efficient. Looks good so far.

But here's the issue.

Currently I pay 2.9pkWh for Gas and 14ppkWh for Electricity. So electricity is 4.8 times more expensive. So there is no way that I can save money. (Unless of course gas goes up a great deal and Electricity comes down - but I'm not into that kind of speculation).

Have I got this right? Am I missing something? I'm going to cancel the survey but thought I'd check with you intelligent and sensible people first.

Many thanks
Install 28th Nov 15, 3.3kW, (11x300LG), SolarEdge, SW. W Yorks.
Install 2: Sept 19, 600W SSE
Solax 6.3kW battery

Replies

  • Martyn1981Martyn1981 Forumite
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    A (well known) energy company is trying to persuade me to replace my boiler with an ASHP claiming that it will save me money. Granted there is a government incentive that will offset some of the capital cost. But by my calculations it still does not stack up.

    The ASHP is claimed to be on average 300% efficient. If I generously assume that my current gas boiler is only 80% efficient then, the ASHP is 3.75 times more efficient. Looks good so far.

    But here's the issue.

    Currently I pay 2.9pkWh for Gas and 14ppkWh for Electricity. So electricity is 4.8 times more expensive. So there is no way that I can save money. (Unless of course gas goes up a great deal and Electricity comes down - but I'm not into that kind of speculation).

    Have I got this right? Am I missing something? I'm going to cancel the survey but thought I'd check with you intelligent and sensible people first.

    Many thanks

    I seem to recall that the average COP in the UK for ASHP's is 2.9, so that seems to match the 300% figure.

    You would also need to factor in cheap(er) leccy sources such as PV excess and E7, I assume? Rather you than me trying to work that out, perhaps you get Z to work out an average?
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Exiled_TykeExiled_Tyke Forumite
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    Martyn1981 wrote: »
    You would also need to factor in cheap(er) leccy sources such as PV excess and E7, I assume? Rather you than me trying to work that out, perhaps you get Z to work out an average?

    Given that my current boiler requirement is about 25kW. so the ASHP would draw about 7Kw. In the shoulder months I'm currently getting about 1-1.5Kw peak. And (until we get batteries) at the wrong time of day (as I still have to go out for work). I'm guessing PV isn't going to contribute a significant saving in it's own right. To make the best of the PV I think Id be better off getting a small 3Kw or so unit to heat a small section of the house. If only I could find someone to fit one. I'm sure you are right about E7 but am already thinking this is too much hassle. (I'm also losing trust as the company has sent through data suggesting much greater savings which simply don't stack up (e.g. gas a 4ppkWh and Electricity at I think about 11p)
    Install 28th Nov 15, 3.3kW, (11x300LG), SolarEdge, SW. W Yorks.
    Install 2: Sept 19, 600W SSE
    Solax 6.3kW battery
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