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ASHP in Hampshire

batalto · 2021-04-22T13:28:11Z

Hi all, Just wanted to talk you through our upcoming ASHP installation. We live on the south coast, just outside of Portsmouth. The house is a detached home of around 260m2 in footprint. The bottom floor was an extended bungalow and we added a second floor. The first floor is standard construction, brick cavity that's filled and double glazed. The upper floor is made of Structurally Insulated Panels (SIPs) with triple glazing. We had to use SIPs because they are lightweight and so wouldn't affect the shallow bungalow foundations. As an upside SIPS are also extremely efficient in retaining heat and have a very low U value, 0.18. The loft has 200mm of insulation in the middle beneath the floor and 400mm of insulation for everywhere else. We have 8.4kW of solar PV on the roof and 7kWh of battery storage (Pylontech batteries). We also have a Solic solar PV heat controller, which will dump excess solar power into the tank before we export. We've just had our EPC done and we scored very highly A (93) that also provided a heat demand of 34w/m2 which tallies with our ASHP assessment of 36w/m2. The ASHP is a 12kw Midea with a stated SCOP of 3.36 supplied and installed by J A Rees, sourced from Freedom Heat Pumps - total cost just under £10k. We will be replacing our current 32kW gas system boiler and hot water cylinder and using the green homes grant for £5k of the cost and I will paying the other £5k. We qualify for the highest RHI so would expect to get roughly £7200 back over the next 7 years. The boiler will be retained as a backup heating system and isolated from the ASHP system. We have been told this is fine with the RHI as its a backup and not hybrid. The heating is currently set to 45 degrees and we have had no problems. Our main living area has a large bifold door system and west facing. This means we have significant heat loss in the winter and for 2 months its very cold and this makes the room chilly, but not cold. All the other months the solar gain is significant, heating the room and the rest of the house. With the conventional boiler the room is chilly, so I am expecting issues in January heating up the room. We might need to come up with a plan for this room, possibly some thick curtains. The install will be next week and should be very straightforward. The ASHP will go on the drive next to the current power intake. The pipework will go straight through the wall into the current boiler room and tap into the current pipework. The tank will need replacement for one with a larger coil, but more or less everything else will remain the same. The aim is 2 days. Currently our gas is 2.5p and electricity is 14p and the current boiler is 58% efficient (according to the boiler) - this leads to a bill of around £1250 for both gas and electricity for the year. With the ASHP, boiler efficiency and assuming a worse SCOP of 2.7 on the current tariff we expect the bill to fall to just under £1,000 (34,000kw of gas to 7,000kw of electricity). This cost includes a standing charge for gas even though we wont be using it. My plan after we have got used to the ASHP is to upgrade the batteries and add 7kw extra, then move to a new tariff. Agile GO is very interesting as I could fill my batteries at night and expend them during the day. The batteries would store 11.4kw (14kW @ 80% Depth of Discharge). I have estimated this would further drop my bills down to £780

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Air Source Heat Pumps (ASHPs)

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batalto

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Topic starter 28/07/2021 1:05 pm

@morgan pretty poor. Although with the GHG having ended, I doubt they are in a rush

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE

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Morgan

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28/07/2021 2:00 pm

@batalto how long after accepting quote and paying initial deposit should I expect contact re the tech’ survey?

Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.

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JulianC

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28/07/2021 2:06 pm

@batalto - when you say waiting RHI, what do you mean? I filled my RHI request on-line and pressed go. And the response came back approved in seconds. Set up my bank account payment and boom. All done.
Our first payment due now

Daikin Altherma 3H HT 12kWh ASHP with Mixergy h/w cylinder; 4kW solar PV with Solic 200 electric diverter; Honda e and Volvo EX30 Ultra Twin Performance electric vehicles with Myenergi Zappi mk1 & Ohme chargers

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batalto

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Topic starter 28/07/2021 2:29 pm

@julianc because of the Green Homes Grant the documents need to be reviewed. I had to submit paid invoices to show how much I paid towards the system and how much the GHG covered. As an FYI my cost was £10,340 and the GHG picked up £5k of that for me. This reduces the RHI by the same amount (£5k)

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JulianC

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28/07/2021 2:34 pm

Arh ok. Understood. I didn’t use GHG

Good luck with all the documents

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Morgan

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28/07/2021 4:32 pm

Posted by: @morgan

@batalto how long after accepting quote and paying initial deposit should I expect contact re the tech’ survey?

Update. Chased them and now have a tech’ survey booked in for 10th August.

Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.

👍

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batalto

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Topic starter 28/07/2021 5:23 pm

@julianc they said it would be up to 10 days. From what I've seen it'll be quicker

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batalto

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Topic starter 30/07/2021 10:13 am

As a note - RHI approved. £219 a quarter for the next 7 years, inflation linked at CPI - more than covers my costs

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JulianC

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30/07/2021 10:24 am

Good news @batalto Is your ASHP fully funded by GHB and RHI?

I have received my first quarterly RHI payment of £357

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batalto

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Topic starter 30/07/2021 10:37 am

@julianc It will be yes.

£10,000 for the whole system

£5,000 GHG

£6,132 RHI (plus inflation)

£11,132 total from the government for the system

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Jeff

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30/07/2021 10:50 am

Be interesting to see what happens if the government go ahead as planned and replace the RHI in March next year with an upfront grant of up to £4,000.

£11,132 vs £4,000 is quite a big difference.

I assume the current RHI is probably unaffordable for the government as the number of installations ramp up.

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batalto

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Topic starter 30/07/2021 1:22 pm

@jeff seems to me like the GHG is just being replaced with a grant £4k less and the RHI is being scrapped. My cost profile would totally change and probably make the ASHP not worth it - unless the price of electricity changes to a much lower base. As is I'll make money and my cost should also reduce due to my solar and batteries