WEBVTT NOTE Transcript 2024-12-17 from FLAC by https://elvery.net/prototypes/transcribe/ on my MacBook Air M1 on maximum quality setting. NOTE Body edited. 00:00.000 --> 00:07.440 Going back to the before times, 2019, when we just had [an] ordinary boring gas 00:07.440 --> 00:12.400 combi boiler and it wasn't condensing, we've had it since we moved into the house about 20 years ago. 00:12.400 --> 00:18.800 Boring gas [] combi boiler, but we've got aerogel wall insulation and the superb Radbots, 00:18.800 --> 00:25.120 and four of us at home and we consumed about 3.1 megawatt hours in gas that year. 00:25.120 --> 00:33.280 For reference, the Ofgem 2017 low gas typical domestic consumption value, was 8 megawatt hours 00:33.280 --> 00:37.440 a year. So we were low and we weren't cheating by heating on the sly with electricity. Our 00:37.440 --> 00:42.560 electricity gross consumption if we had had no solar PV was 2 megawatt hours for that year 00:42.560 --> 00:50.000 compared to the Ofgem 2017 low class 1, which means when you're not heating with electricity 00:50.000 --> 00:56.640 of 3.1 megawatt hours per year. So we were low on both scales. Class 2 users may be all electric 00:56.640 --> 01:02.880 heating with storage heaters or whatever and high is much higher for class 2 in that one. Net exports 01:02.880 --> 01:08.480 were about 1.9 megawatt hours for that year. A little thing called the pandemic stopped me 01:08.480 --> 01:12.960 putting in the Thermino. I was ready to go in early 2020 but kind of it didn't seem the to be the most important thing to be doing at that moment. But finally, it got round to 2022, and in March 01:19.360 --> 01:24.320 the Thermino and the Eddi went in. So for reference in case any of you don't know, 01:24.320 --> 01:29.120 when I started this thing this Sunamp product line was called Uniq. By the time I'd actually 01:29.120 --> 01:34.000 got around to doing it in 2022 it was called the Thermino and I went for a size equivalent to 01:34.000 --> 01:42.880 about 150 litres water tank and the Eddi, the myEnergi Eddi, which I wanted to use for a solar 01:42.880 --> 01:47.920 diversion but also because it was highly controllable remotely and there's some nice stuff on the 01:47.920 --> 01:54.479 Internet, people showing how to do it, so that I could choose to top up the Thermino when there were low grid [carbon-intensity] times. So the first curiosity when I got the Thermino was that when I filled it up 01:58.560 --> 02:03.520 the first time nominally it holds seven kilowatt hours roughly but when you're but that's when it's 02:03.520 --> 02:08.000 hot so you draw that seven kilowatt hours worth of heat and it's still just hot enough whatever 02:08.000 --> 02:13.760 that means I think 45 degrees or something. When you're heating from cold mains water in March 02:13.760 --> 02:19.520 actually it's more like 10 kilowatt hours and ours [DHW consumption] is about four kilowatt hours a day so that implies it's just short of two days' worth which is just about right. But anyway there's a very clever valve which we have in our system called the Intasol valve which is entirely mechanical - 02:28.160 --> 02:32.880 there's no electronics, computing, Internet, anything. So it's designed to work with a 02:32.880 --> 02:38.000 combi and a thermal water store and our Thermino looks like a solar thermal water store to it. 02:38.000 --> 02:42.240 If the output of that when you turn on tap if the output is from that is hot enough it just uses 02:42.240 --> 02:47.280 water straight from that although it then has a tempering valve to cap the temperature at 50 02:47.280 --> 02:52.880 degrees to prevent scalding. If the water from the Thermino is not hot enough to use directly, ie 02:52.880 --> 02:58.320 it's below about 50 degrees it routes it very cleverly it mixes it down to 28 so any 02:58.320 --> 03:03.920 combi will accept it and feeds it into the Thermino so it bleeds residual heat into the 03:03.920 --> 03:08.800 combi to reduce your demand so you really get that 10 kilowatt hours of storage. So in fact 03:08.800 --> 03:12.720 therefore internally my measure that I'm not allowed to share with you because of an NDA with 03:12.720 --> 03:20.560 Sunamp shows between zero and 100% [well] minus 30 and 100% well actually 110% because you can 03:20.560 --> 03:24.880 overfill it with diversion a little bit get a little bit more in and I don't do that when 03:24.880 --> 03:29.280 I'm topping up from the grid so it means that if there's ever some sunshine I don't expect 03:29.280 --> 03:34.160 it can still be absorbed by the system. Our DHW demand about four kilowatt hours a day is 03:34.160 --> 03:39.360 something like a megawatt hour a year and with diversion about half of that so basically all of 03:39.360 --> 03:45.600 summer and some of the shoulder months is covered. It's 500 kilowatt hours a year. And if you look at 03:45.600 --> 03:50.640 the chart you'll see the green bars are where it's diverting (this is for September in the year it 03:50.640 --> 03:55.680 went in 2022) and you see the start of September it's basically all green and that shows we were 03:55.680 --> 04:00.720 using water most days right so that it was topping it up but then towards the end of the month we're 04:00.720 --> 04:06.400 starting to use boost. The boost top up from the grid but it's complicated it says what's the 04:06.400 --> 04:10.240 threshold. The black is what's the threshold for grid intensity I'm going to use for allowing top 04:10.240 --> 04:16.480 up. The green and sort of yellow squiggly line near the bottom is grid intensity actual grid, so grid means it's 'super-green' which means it's in the bottom quartile 04:22.000 --> 04:28.480 for the last week and there is no storage being drawn down into the grid which means probably 04:28.480 --> 04:34.480 the storage is topping up so maybe we should too. And the little yellow plus signs are samples 04:34.480 --> 04:39.440 where the Thermino is indeed being topped up. Interestingly the little black crosses are when I 04:39.440 --> 04:43.920 respond to dips in grid frequency and stop topping up so I'm providing a tiny amount of grid 04:43.920 --> 04:49.360 frequency support as well. And as I gained more confidence in this I made the boost algorithm 04:49.360 --> 04:55.120 more aggressive so for example last year we basically drew almost no gas for hot water - only 04:55.120 --> 04:59.520 for space heating - so only in the winter so we basically had zero effectively zero gas bills 04:59.520 --> 05:04.640 other than standing charge most of the year and that's only done as I say oh there's a an actual 05:04.640 --> 05:13.120 cap on this top up of being 170 something grams of CO2 per kilowatt hour so it will only top up 05:13.120 --> 05:18.160 when it's less carbon to top up the Thermino and use it from there than it would be by burning gas 05:18.160 --> 05:22.400 directly. So our footprint is lower than it would have been we used virtually no gas and it all got 05:22.400 --> 05:28.080 turned off when we were capped at the end of November... So ... The Present - Heat-pump and Eddi ... so ... 05:28.080 --> 05:33.360 At the end of November, well at the start of November middle of ... November, we disconnected the 05:33.360 --> 05:39.920 Thermino from the combi so that when Octopus would come in they would just have a plain combi system 05:39.920 --> 05:44.720 to upgrade but various things to try and make sure that it would all go back together again. 05:44.720 --> 05:48.800 Well it hasn't it's not perfect we're going to have to do more work than I wanted to but it's OK. 05:48.800 --> 05:55.440 But for the moment we have a relatively vanilla Daikin heat pump with water cylinder curiously 05:55.440 --> 06:02.960 160 litres nominal so nominally the same capacity as the Thermino but three times the size and we 06:02.960 --> 06:09.920 have DHW, domestic hot water, and space heating from that and it's running right now. The interesting 06:09.920 --> 06:14.800 thing is that generally for electricity ignoring anything to do with PV or whatever and ignoring 06:14.800 --> 06:20.720 heat we use about five kilowatt hours of electricity per day in the house and the space heating and 06:20.720 --> 06:24.800 domestic hot water together via the heat pump is coming to about the same day so it's roughly 06:24.800 --> 06:28.320 doubling our electricity consumption. Which is fine. It's probably going to be true for the whole of 06:28.320 --> 06:33.040 this month it doesn't look like it's going to get much colder. This is a sort of mildish month. So 06:33.040 --> 06:40.400 the Eddi was driving [the] Thermino via its heater output one and we diverted that instead to control the 06:40.400 --> 06:49.040 immersion heater on the hot water tank. So normally once a week the heat pump system is programmed to 06:49.040 --> 06:55.440 use the immersion heater to raise the whole hot water tank to about 60 degrees C to ensure that 06:55.440 --> 07:00.240 any legionella is killed. Now, you don't need to do it once a week some people do once a day some 07:00.240 --> 07:05.120 people keep it permanently at 60 - you don't need to do that. We probably turn over half the tank 07:05.120 --> 07:12.080 volume every day and none of us except possibly me as the oldie in the house are in any way 07:12.080 --> 07:17.840 vulnerable. I do baths rather than showers anyway and so I have now modified it to be a bit smarter 07:17.840 --> 07:23.520 which says it waits eight days since the last time the tank was at maximum temperature and then in a 07:23.520 --> 07:31.520 slot in the morning between midnight and 6am if we get to super green it will then run the 07:31.520 --> 07:37.120 pasteurisation cycle then which takes about three kilowatt hours. If that hasn't happened by 14 days 07:37.120 --> 07:41.760 in - and I could push that out if I was feeling like it - if that hasn't run by 14 days 07:41.760 --> 07:47.920 it forces one the next morning. Now, that reduces the overhead. If I were running a pasteurisation 07:47.920 --> 07:53.600 cycle every day that would be throwing away about well that would be heating putting in about three 07:53.600 --> 07:59.520 kilowatt hours of heat at a CoP [Coefficient of Performance] of 1. By doing it every sort of 10 days I expect this to be it's an 07:59.520 --> 08:05.440 average of 0.3 kilowatt hours per day at a CoP of 1 and the rest of the CoP of I reckon I'm 08:05.440 --> 08:11.280 estimating them between two and 2.5 or better so it's diluting that a lot less and it's doing when 08:11.280 --> 08:19.120 when grid intensity is low it's nice on the grid demand is low. On my Eddi I have - I had - a spare 08:19.120 --> 08:26.000 slot for a current clamp and so I put on a second one for that to monitor the entire supply to the 08:26.000 --> 08:32.640 heat pump so the H4 boundary. And interestingly even [the] little OpenTRV box and so on are all supplied 08:32.640 --> 08:37.600 via that even though it goes out the front of the house to the heat pump, through the heat pump, down 08:37.600 --> 08:41.600 underground, through the wall, and all the way around the side of the kitchen, it's all supplied from 08:41.600 --> 08:46.000 there. And when it's quiescent so when it's not doing any heating of any sort hot water or space heating 08:46.000 --> 08:51.520 that's using about 10 or 11 watts which is not bad. Interestingly the circulation pump on its own 08:51.520 --> 08:56.720 adds about another 50 watts. And I've set out with this heat pump that it is not [connected to the Internet] because at the moment 08:56.720 --> 09:01.680 doesn't need to be connected I've set it up all sensibly statically so for example it keeps the 09:01.680 --> 09:10.320 hot water at 45 degrees basically from 7-ish 7:30 in the morning till 4 pm and then from 7 pm 09:10.320 --> 09:17.120 till 9:30 the rest of the time it will keep it to 42 degrees so we use less hot water at peak times 09:17.120 --> 09:22.320 heating electricity for hot water. My son just ran a bath 10 minutes to four so it kind of nearly 09:22.320 --> 09:28.320 defeated the mechanism just now but it still uses less. Radbots are controlling call for heat for the 09:28.320 --> 09:33.600 space heating and it's an on-off thing and many installers will absolutely hate that. And I wrote 09:33.600 --> 09:38.320 my first academic paper about why we should microzone and why TRVs should be fine but they 09:38.320 --> 09:42.560 also would absolutely hate the fact that it's microzoned and not running all the time. 09:42.560 --> 09:48.880 (I think I can get all these 3D graphs on at once.) The top one is temperatures as seen by the Radbots themselves 09:48.880 --> 09:53.120 on the TRV so [] the temperature doesn't wave around quite as much as that. That's 09:53.120 --> 09:58.640 a temperature [] right next to the radiator. Bottom trace is a spare Radbot I shoved 09:58.640 --> 10:04.080 outside in our porch and interestingly it now gets the cold breeze from the from the heat pump 10:04.080 --> 10:09.360 so it's a lot more wobbly temperature than it used to be. The next one down with a purple line shows 10:09.360 --> 10:14.800 call for heat to the heat pump and you see it's only on about maybe a third of the time. And when 10:14.800 --> 10:21.120 we get down to design temperature at minus two degrees outside which will be about three times 10:21.120 --> 10:27.040 the heating degree days I think that won't quite get up to 100. But an interesting point running it 10:27.040 --> 10:32.320 like this is if I ran it all the time the way the installers would like me to I'd be spending a 10:32.320 --> 10:38.640 kilowatt hour a day just running the pump. I'm spending I'm saving two thirds of a kilowatt hour 10:38.640 --> 10:43.920 just on not running the pump so I could have a slightly less good CoP and still be ahead by 10:43.920 --> 10:49.200 by avoiding that parasitic load. There are options in the Daikin to only sample running and so on. 10:49.200 --> 10:55.120 Anyway, next graph is percent open each of the TRVs and when it's over over 49 then it's calling for 10:55.120 --> 11:01.040 heat. So this is in the week coming up to a few days ago. What's in the future? I'll [reconnect] the 11:01.040 --> 11:06.560 Thermino. I'll change the algorithm for top up to say that when the current grid intensity is about 11:06.560 --> 11:12.880 a factor of two or better lower than the average for the last seven days or the carbon intensity 11:12.880 --> 11:17.840 dot org national grid prediction for the next two days then I will top up the Thermino on the grounds 11:17.840 --> 11:24.800 that although I'm topping them up with CoP 1, immersion electricity, actually I'm gaining a 11:24.800 --> 11:29.680 factor of two because I'm storing energy now that I do not have to get from the grid when 11:29.680 --> 11:32.240 the intensity will be higher later.