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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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Mars

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02/11/2021 10:12 am

Posted by: @batalto

At this exact moment I have an E0 low flow fault on my system. Essentially it refuses to run as it thinks the flow rate is too low for the pump... So no heating... Plumber is coming tomorrow, apparently there is a filter to clean out? Why I wasn't shown how to do this is beyond me. I'm sure I could have it out in 5 minutes and everything running again. Hot water is at least full, but wife and baby are not happy about a cold night. Typically it's quite chilly this evening as well. Hopefully the house holds the temperature this evening.

This has happened to us twice. The dreaded filter. Ours was located in a silly place and we had it moved as part of our last maintenance so that's much more accessible. You'll find that there's some corrosion in the filter hindering flow.

Ridiculous that you weren't told about this.

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batalto

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Topic starter 02/11/2021 10:20 am

@editor plumber will be here later in the day and i've asked him to show me how to do it myself. House was pretty good overnight and seems to have held temperature well. Luckily we have lots of solar gain in the day and we ran the A2A this morning to heat things up - worked very well to get rooms up to temperature. Just doesn't heat up the whole house

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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batalto

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Topic starter 02/11/2021 10:22 am

@heacol I've reset it several times - it works for a bit, then conks our again with E8 fault (low flow rate). E0 is just E8 three times in a row.

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Brendon Uys

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02/11/2021 10:38 am

@batalto Have you turned your thermostats and TRV's up full?

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batalto

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Topic starter 02/11/2021 10:41 am

@heacol yes - it trys for a bit, you can hear the water flowing, but then it stops and pulls the error message

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Brendon Uys

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02/11/2021 11:53 am

@jeff Based on those figures, I am drastically undercharging!!

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batalto

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Topic starter 02/11/2021 12:06 pm

Now fixed - pulled out the filter and it was completely gunked up with crap. Washed it out, popped it back in and reset the unit. No issues, all running fine again. Literally a 3 minute job. Next time I'll just do it myself. I am amazed by the amount of rubbish in there though. Goes to show that my old system never had a gauze filter, only a magnetic one. As a side note, the pipes are now silent whereas before they made a noise - I guess as the water tried to push past the blockage.

Also its very usefully located inside the house/boiler cupboard. Just need to get the right wrench now.

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Mars

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03/11/2021 11:13 am

@batalto, that happened to us too. Once you know where the filter is, it's super easy to clean. Takes a few minutes. Are you up and running again now. We also discovered that once the filter was cleaned, it would clog again a few minutes later, and after 2-3 'flushes' it would be clean and run normally for a lengthy period of time.

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Mars

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03/11/2021 11:14 am

This is where our filter used to be and how we cleaned it. It's now near the cylinder so much easier to clean.

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batalto

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Topic starter 03/11/2021 11:16 am

@editor yes all running again fine. House is very warm, but I think this is due to radiator balancing. Its amazing the difference balancing them has made. Its still not perfect as one is basically still cold and the others are warm. Maybe a pump upgrade might be useful or as Heatcol is suggesting that we just use the ASHP inbuilt pump power

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batalto

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Topic starter 03/11/2021 10:10 pm

@editor I check it again this evening and this is the result. One day and it's gunked up again. I think I'll check it everyday for the next week and see just how much is building up. At least it's a 2 min job to do it.