Ashp & sahp combined system

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martindias
martindias Posts: 79 Forumite
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in Green & ethical MoneySaving
I am refurbishing an old 4 bed detached victorian house and a one bedroom apartment (annex granny flat). It is really back to basics replastering, new damp course, totally new can-heatin. all round double glassing - extending 3 meters at the back to make big kitchen plus sun lounger for the annex. There will be 4 ensuite bathrooms and one bigger family bathroom.

Now I 'happened' on a Eco Heat website and next thing I had a very nice 'engineer' round selling me a new Air Heat Pump and integrated SAHP. Now I know good insulation is vital to make these things work well but my question is - Is £16000 really worth it? I'm told there are government grants available to encourage converting (I'm told for my size ASAP £1900 pa for 7 years) to air source heating system but I am really concerned that the heat they generate will be sufficient. Currently I am on gas central heating and the boiler is a thrillion years old - actually now it's in a skip waiting to be carted away.

Any words of caution, encouragement., advice most welcome. Could I be future proofing myself from the gas prices rises which seem inevitable?
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  • 1961Nick
    1961Nick Posts: 2,072 Forumite
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    martindias wrote: »
    I am refurbishing an old 4 bed detached victorian house and a one bedroom apartment (annex granny flat). It is really back to basics replastering, new damp course, totally new can-heatin. all round double glassing - extending 3 meters at the back to make big kitchen plus sun lounger for the annex. There will be 4 ensuite bathrooms and one bigger family bathroom.

    Now I 'happened' on a Eco Heat website and next thing I had a very nice 'engineer' round selling me a new Air Heat Pump and integrated SAHP. Now I know good insulation is vital to make these things work well but my question is - Is £16000 really worth it? I'm told there are government grants available to encourage converting (I'm told for my size ASAP £1900 pa for 7 years) to air source heating system but I am really concerned that the heat they generate will be sufficient. Currently I am on gas central heating and the boiler is a thrillion years old - actually now it's in a skip waiting to be carted away.

    Any words of caution, encouragement., advice most welcome. Could I be future proofing myself from the gas prices rises which seem inevitable?
    £16,000 is a lot of money & it still leaves you with the problem of heating the DHW ... 5 bathrooms sounds like a major HW requirement!

    I think I'd get the most efficient opentherm boiler I could & control it with Honeywell's Evohome kit - smart TRVs configured for Heat-on-demand. That should leave plenty of money for a solar array & immersion diverter.
    4kWp (black/black) - Sofar Inverter - SSE(141°) - 30° pitch - North Lincs
    Installed June 2013 - PVGIS = 3400
    Sofar ME3000SP Inverter & 5 x Pylontech US2000B Plus & 3 x US2000C Batteries - 19.2kWh
  • Martyn1981
    Martyn1981 Posts: 14,764 Forumite
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    Hiya, I assume it's an ASHP but a 'wet system' (air to water) to provide all the heat and domestic hot water?

    It should provide enough heat, but you need to make sure it's suitably sized to cope in the coldest period. At that time, not only do you need more heat, but the system will be less efficient as it's extracting heat from ever colder outside air. So it may need to run 24/7 during those periods.

    These systems are typically quoted as around £8-£10k, but if you have a large property that might explain some of the higher price. But probably worth you getting a few quotes.

    Also check your EPC which should state the kWh's of heating the property will need, as I think that'll be the limit of how much RHI you can claim each year (kWh's x 10p (ish)).
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW). Two A2A units for cleaner heating.

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • martindias
    martindias Posts: 79 Forumite
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    Very helpful. Many thanks. It never had an EPC and is now without a roof. I’m trying to include in the rebuild as much insulation as possible but without having a concrete floors throughout. Solid floors will be restricted to the new extension only. Yes it’s an air to water system I’ve been quoted for and yes already requested three other quotes.
  • markin
    markin Posts: 3,848 Forumite
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    edited 11 November 2019 at 12:39PM
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    If its got no cavity wall it may cost 16K a year to run.




    You should read the threads over in 'ENERGY' - LPG, Heating Oil, Solid & Other Fuels forum
    https://forums.moneysavingexpert.com/forumdisplay.php?f=78
  • martindias
    martindias Posts: 79 Forumite
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    edited 11 November 2019 at 3:39PM
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    Has cavity insulation and I'm currently having additional internal insulation back plastered board put on the inside of all external walls. I guess, along with fairly generous thermal underlay on all downstairs flooring, I'll have maxed out on possible improved insulation.

    Now reading the thread your referenced - many thanks. I am learning a lot.
  • ABrass
    ABrass Posts: 1,002 Forumite
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    Insulation backed plasterboard is generally seen as more expensive, lower performing and harder to work with than buying separately.

    16k is GSHP territory. I'd be looking for a lot more quotes.

    Underlay is better than a kick in the teeth but if you've got the space available under the suspended floor then you can stick down some insulation between the rafters. It's a bit of a pain but if you're not yet finished on the rest of your work then it's worth considering.
    8kW (4kW WNW, 4kW SSE) 6kW inverter. 6.5kWh battery.
  • Martyn1981
    Martyn1981 Posts: 14,764 Forumite
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    jeepjunkie wrote: »
    What does the £16k include?

    We paid ~£12k for our EcoDan, but that was the biggest model and included about 16 designer fancoils and ufh.

    No issues at all heating a 100+ year old house with improved insulation but still rubbish compared to a modern house.

    Although we had a 210lt tank with a solar diverter that in no way would be enough for that many bathrooms if heavily used.

    System never ran 24/7, totally unnecessary, temp was set not to drop below 17c during the night which it almost never did even in winter.

    Running costs, cheaper than my highly insulated new build on gch, go figure...

    Can I just ask (asking for a friend .... yeah right!) how big the property is? Rooms/m2 would both be gratefully received. Consideration is for a recently purchased large property with 2 oil boilers, off gas grid, but potential (hopefully easy potential) for 3phase. Would be nice to avoid burning diesel.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW). Two A2A units for cleaner heating.

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • zeupater
    zeupater Posts: 5,355 Forumite
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    martindias wrote: »
    I am refurbishing an old 4 bed detached victorian house and a one bedroom apartment (annex granny flat). It is really back to basics replastering, new damp course, totally new can-heatin. all round double glassing - extending 3 meters at the back to make big kitchen plus sun lounger for the annex. There will be 4 ensuite bathrooms and one bigger family bathroom.

    Now I 'happened' on a Eco Heat website and next thing I had a very nice 'engineer' round selling me a new Air Heat Pump and integrated SAHP. Now I know good insulation is vital to make these things work well but my question is - Is £16000 really worth it? I'm told there are government grants available to encourage converting (I'm told for my size ASAP £1900 pa for 7 years) to air source heating system but I am really concerned that the heat they generate will be sufficient. Currently I am on gas central heating and the boiler is a thrillion years old - actually now it's in a skip waiting to be carted away.

    Any words of caution, encouragement., advice most welcome. Could I be future proofing myself from the gas prices rises which seem inevitable?
    Hi

    Can you provide more details on what the combined ASHP/SAHP solution comprises as raised in the highlighted text above? ...

    Are we talking about a heat pump with external passive heat exchanger panels to provide a level of "Solar Assistance" in the exchange process ??

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • martindias
    martindias Posts: 79 Forumite
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    The house heat requirement Is estimated at 30784 KWh being approx 216 sq meter. The engineer has recommended a 16KW LG Terma VC ASHP and a BMTB 300 SAHP solar assisted pump to go with it - to augment the water heating and a system that can run throughout the year to provide constant hot water. Both are apparently eligible for the Renewable Heat Incentive payments.
  • martindias
    martindias Posts: 79 Forumite
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    216 sq meter and estimated heat requirement of 30784 KWh
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