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Last seen: May 10, 2026
About Me
Solar since 2011 4kW peak output; 19kWh Growatt Battery; BMWi3 EV and access to Octopus Intelligent Go 7p/kWh off-peak; 1905 detached house which has been thoroughly insulated to EPC B. Blower test showed 0.49 ACH. Heat Loss calculated 7.1kW.
Sept 2025 installed a new Vaillant aroTHERM 7kW heat pump, 300L Vaillant Unistor tank, 26m2 underfloor heating downstairs and upgraded radiators to cope with design calculated to meet 8kW heat loss. Combined heating and water SCOPs ranging between 3.5 and 5 between November and January.
Also added Daikin aircon in 30m2 Granny flat for summer cooling and winter heating SCOP >4.
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Slowly built up 4kW peak PV, 19.5kWh battery system, BMW i3 got us Octopus Intelligent Go low price off-peak supply, thorough insulation to EPC B in detached 1905 home, underfloor heating 26m2 of total 160m2. Vaillant 7kW pump, Unistor 300L cylinder. All working well and saving £1,500 / year versus gas central heating.
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Latest Posts
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RE: Heat Pump Manufacturers Recommending Buffer Tanks
@tony-stolz, I think @jamespa has already covered the h...
By Mars , 9 hours ago
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RE: Heat Pump Overpromising – What Were You Actually Told Before You Bought?
@jamespa that’s actually a really interesting observati...
By Mars , 9 hours ago
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RE: How many people are happy with their ASHP and do you believe them?
Good luck, I spent a couple of hours and, whilst I foun...
By JamesPa , 10 hours ago
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RE: Heat Pump Operation in Summer - Valliant 7kW
I do the same: cool my large buffer (3000L) to 10C, pum...
By upnorthandpersonal , 18 hours ago
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@editor "The interesting bit is that many modern invert...
By Singlespeed , 18 hours ago
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RE: Ecodan & MelCloud scheduling
With the prospect of warmer weather this week, I brough...
By downfield , 20 hours ago
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RE: A2A vs A2W: Which Heat Pump Would You Pick?
I reached out to MCS directly last week on this and her...
By Mars , 20 hours ago
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Mentally you have to separate the ac side and the DC si...
By JamesPa , 1 day ago
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RE: Help me keep the faith with my air source heat pump installation
My heating developed a really severe case of noise and ...
By JamesPa , 2 days ago
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RE: Octopus Cosy 12 Heat Pump Regret: Incredibly Loud, Poor Heating & Constant Hum - Help!
@l2jad I was just thinking all things being equal. Our ...
By AndrewJ , 2 days ago
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Hi, Does anybody have experience with Heat Geek insta...
By sttpd1917 , 2 days ago
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I will soon be struggling. Admittedly it is the summer,...
By Batpred , 3 days ago
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RE: Indevolt Batteries UK Support & Info Thread
Not known yet. I've asked a local Councillor to follo...
By Transparent , 3 days ago
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Hard to tell but I think I have placed the arrow on wha...
By ASHP-BOBBA , 4 days ago



