Greenbot

PM sent (J Pearse). I'm planning to document my experieces and my system on some sort of blog as I've had a lot of questions in the real world. For any interested that read this, I'll post a link when I do. The headlines: - Poor installation by an experiences company, mainly wiring and setup errors. - I added radiators to keep our existing pretty column radiators, all pipework is 22 or 28mm to all radiators. - One winter with the original radiators ran fine. - With increased radiators and improved pipe diameters, installation mistakes rectified and settings all taken care of, I'm now fine tuning tun times and temperatures. I've ran during October at 28-32C, in a very normal 1930s semi (basic insulation measures only), and COP has been 5 +/- 0.3 (!). - We'll see what happens in colder weather, but I am very happy with the system, if not the company that installed it and the amount of time I put into finding their mistakes!

Excellent question; yes I did. We currently run an Audi A2 that owes us nothing (had one for 10 years, then replaced it with another for well under £3k) and because we cycle to work sometimes, it's not going to make much of a dent to go electric - 2 of us do about 8,000 miles a year together, max. But we will go electric in a couple of years because I am sick of maintaining older cars (18 years and counting). No problem, glad it's interesting! Thanks, I'll look into that at some point hopefully - I wish I'd blogged about the last 4 years but I wasn't doing anything unusual then!

Yes I was referring to the forum we're on and I appreciate that buildhub is a self-build forum. I share the concern that some companies are biased and the risk of unsuitable systems is real, but I've vetted installers as much as possible, spoken to previous customers and read into their over 10-year long histories. Yes, although costing money is not the only cost I think we should consider. When I weigh up the reduction CO2 emissions (I can expect around 67% decrease according to this: https://www.london.gov.uk/sites/default/files/heat-pump-retrofit-in-london-v2.pdf), I could argue that heat pumps are cheaper all things considered. We need to consider all of the materials we use in building too; there's some excellent progress in Europe with increased timber for example. I appreciate your replies to my thread ProDave, I hope the above isn't read as confrontational - just my answer to the 'why should they because gas is so cheap' question. It's a like the ICE vs. electric car debate, I'd love to drive a 6-cylinder NA monster around but it just seems wrong to me and I hope that the subsidies for fossil fuel will reduce in future. Thanks ?

Indeed... I'm sure that's a rhetorical statement the forum we're on is for renewables, but obviously the answer is for the sake of sustainability and air pollution ? I'm considering learning how to blog to document our install before and after, in hope that it may inspire others and answer the questions I've spent hours researching. I've only found one such example but his heat demand for a terraced house doesn't compare to our semi unfortunately. And my installation is a lot more. https://tomkiss.net/life/one_year_with_an_air-source_heat-pump Still a very useful starting point for research and one that informed my decision.

Indeed... I'm sure that's a rhetorical statement the forum we're on is for renewables, but obviously the answer is for the sake of sustainability and air pollution ? I'm considering learning how to blog to document our install before and after, in hope that it may inspire others and answer the questions I've spent hours researching. I've only found one such example but his heat demand for a terraced house doesn't compare to our semi unfortunately. And my installation is a lot more. https://tomkiss.net/life/one_year_with_an_air-source_heat-pump Still a very useful starting point for research and one that informed my decision.

That's an excellent description, thanks. I wasn't aware that £5k was needed for a certificate either. I believe UK building regs will change in future toward better standards, it's a shame all new builds aren't currently somewhere near this. If I achieve my own self- build I couldn't not aim for that performance, but many people don't seem to be interested.

Thanks, that's what I understood for PV. My EPC is high D, BUT that was not including the report's suggested under floor insulation with air barrier and double glazing / door upgrades which were recently completed. My neighbour (practically identical house with far less insulation measures) is listed as C. I've took a look at that whole thread; they seem to be chasing down power usage and using a lot of power. It's going to be very interesting to see my actual use when i go through with it. Thank you, I feel like I'll need it... Out of interest, your house sounds great and such a home is my long term goal (maybe a bit smaller!) but I though Passivhaus / passively insulated would require a barely and heat. It's clearly a beautiful large home and therefore 12kW must still be very efficient, so what does passively insulated actually mean?

I would love to add PV in future, but the budget won't stretch with a wedding and our garden and driveway to complete - hopefully in a couple of years! The storage heater is a great ideal though, I will look into those thank you. What we need is for the government to reduce the gap between gas and electricity prices to reflect their environmental impact - especially as we have more renewables coming into the grid. 16p for electricity vs 4p for gas is not right...

Thank you very much for that, it's good to have another person check the calculations! The 7kW pump certainly would have struggled. My boiled would have used 15,000kWh at about 93% efficiency, and that was including DHW. My gut is that with the insulation (new door and bay windows) and draft proofing I've now completed should hopefully mean we'd use closer to 13,000 kWh [ (15000 x 0.92 = 13,800), assuming 95% is space heating = 13,110kWh). Wow - thanks. My DHW cylinder is going in the garage but I don't think it should be ALL water storage! I assume the lower water temperatures of an ASHP requires a larger volume. The current plan is for a water cylinder that has an immersion heater, so solar PV in future would be compatible. I am wondering if I should attempt to keep options open for solar thermal in future via a thermal store, or whether it's viable to go for a large enough thermal store to use cheap electricity to contribute toward space heating? I'm still hoping to hear from anybody who has retrofitted any similar ASHP to an older house.

Thank you for your replies. I've not done anything special - I tried to do everything I could when renovating on a budget, but I didn't know as much as I do now. I've listed everything I've done already. Good point on the gas comparisons - I used 2 years running on gas (with draughty old front door and a large, rotten single glazed bay window which are now replaced) and our usage (with 2 bedrooms rarely heated) was almost exactly 15,000kWh. I calculated that as 14kW based on the boiler efficiency, and using an SCOP of 2.5 calculated the electricity demand for the heat pump to be 5500kWh. That's included working at home in lockdown 1 and 2 up to December 2020. I don't know if I can work out how to convert that to the power required for the heat pump, however I wanted to option to extend into the loft down the line so I've decided to upsize to the Daikin Altherma 3 H HT, which has far greater output (but the upgrade was a painful price). My motive is indeed to reduce C02 - it's the right thing to do, and I want to tell the younger generations that I did my best. In my opinion, if you are lucky enough to be ABLE to afford it, you should - and I am poor at spending my money. We're not rich - we work in the public sector and neither of use earn near a GP salary. I'm prepared for the slightly higher bills, and thank you for your comment. Yes; the concern about that is a factor in deciding to upgrade to the Daikin and you've just made me feel better about that decision! Baxi 38kW, very oversized - my partner's dad is a plumber and helped with the refurb! Can you advise how to better check the heat loss? One company spent 90 min here measuring up and provided a detailed breakdown, and did our EPC. Another question - does anybody use a thermal store to take advantage of Octopus energy flexible tariff, so you could have 4p/kWh electricity pre-4pm and then heat the house in the evening? I've not calculated how much heat would be useable from that but it would help and be future compatible with either type of solar panels that I would love to fit down the line. It's all very interesting but the mind boggles at the number of factors you have to consider!!

Hello, I have committed to an ASHP to be retrofitted but I am concerned about it's performance, and whether I'm making a mistake. We renovated our 1930s, 130m2 3-bed semi back to bare brick and joists over the last 5 years, and despite my efforts at the time I couldn't get advice on low-carbon heating (and couldn't afford it at the time either). What I am not working with is all new 22/15mm copper pipes in a 2 zone (up/downstairs) system on a very efficient gas combi. The radiators are only just large enough for running at 55 degrees - I should have gone larger but they are expensive designer items that we will not be replacing, so we are comfortable with them at 55 degrees but I will be adding a couple of radiators in larger rooms to lower the running temperature. The house has topped up loft insulation (300mm), all LED lights, cavity wall insulation (government grant 5 years ago), all double glazing, new composite doors, and I've installed floor insulation for the suspended timber (100mm mineral wool and air-tight membrane sealed around the perimeter of each room). I've done a decent bit of draft proofing but need to look at the spot lights and consider a MHVR system for the bathroom next. We see cold spots in the bathrooms where water vapour condenses on the dot and dab plasterboard performing thermal bridging. The house has a mini-extension joining the garage to the house which has been converted from single-brick walls to a stud liner wall with 100mm extruded polystyrene insulation; pipes from the heat pump will pass under the floor into the main house (6m). We already have a wood stove for additional heating if required. Heat loss calculations say we're at 6.9-7kW at -3degrees, from 2 installer surveys. We're provisionally going with a 7kW heat pump, a buffer connection it to the 22mm pipework coming into the house and a 200l DHW tank. What I really need is to hear that somebody has a similar house and system, how well it works and their real-world running costs. The GHG is very delayed, and due to other factors I'm considering pulling the plug. My motivation is doing the right thing for climate change, so I don't expect total financial sense, but I also can't spend the coming years ripping it out and starting again / changing things if I get it wrong. Thank you in advance, and please ask if I've missed anything.

Afternoon all, I've just found this forum and it seems to be what I need! I've just renovated a 130m2 semi over the last 4 years, and I applied for the green homes grant in October... I am very nervous about going ahead with an ASHP and looking for some real-world experiences, which I'll start a thread for. What I've read on here so far has been very useful, thank you! I'm pretty well educated on the heat pump topic but there is precious little reassurance to be had when nobody I know has heard of them. I live in the north east, so not the coldest but not warm either! Thanks!