RobLe

I’ve had a pp3 type of these usb lithium cells in a smoke detector. Thought it was great at first, then found it has high self discharge (not normally an issue with lithium), and lower energy store. Upshot was it only lasted a couple of months in a smoke detector, while a non usb rechargeable lithium lasts years before it squarks. Don’t flatten them tho, no bms inside cheapie pp3 lithium.

Embodied CO2 of the new concrete poured into foundations if you dig out what’s there. Will the new building be heavier or lighter than the old, would influence my thoughts.

We have a hybrid battery system, smart meter, octopus go. Import 7.5p (from 00:30 to 04:30), export 8p. Lots and lots of effort, octopus took forever to gets things right(it’s still not), it’s now almost as good as the spinny meter would’ve been. 👿. There are better rates, octopus io notably, we would need another meter upgrade and no doubt lots of time talking to octopus, gah. We must’ve lost our spinny meter 15+ years ago - if you have one it’s like a magic 100% efficient, infinitely big battery😈. I guess if you import a lot more than export (all elec house + car) then there is an incentive to go smart and get a tou tariff.

A ‘gold dust’ spinny wheel meter! Technically theft when it spins back, so using the grid as storage. Morally fine imho to do so, you’re probably on average exporting when the country needs electric. Or get a hybrid battery, smart meter, Octopus tariff, jump through loads of MCS hoops, and be back more or less where you were with the spinny wheel meter. So long as the dno is aware, afaik it’s not your ‘fault’. Don’t send meter readings lower than the previous, that’s asking for it! Elec car charge point, give elec away in summer ? 😈

I’ve given the spec a quick look, didn’t see any sign of it being inverter driven. Your neighbours will likely hate you if it’s not got an inverter driving the compressor - that’s what allows quiet low power operation most of the time, reserving full power for a cold snap. Old design non inverter units clank when they start up, most annoying. They’d start and stop a lot, so lots of clanking.

A bit of rummaging around the internet and I found this, I think it’s what I’ve seen before, but I’m struggling to get the simple glycol is 2x worse than water from it. Note that at the time, I actually initially measured a 3C drop for our gshp propane-glycol bphe - then in feb or so when it started to freeze a little I added glycol. With the same 40W pump this dropped the flow from 18lpm to 12lpm (memory), and increased temp across the heat exchanger to 6C. Anyway, here’s that paper, maybe it helps… https://onlinelibrary.wiley.com/doi/pdf/10.1002/9783527621583.app2 As corroborating evidence, I notice that commercial gshp units tend to have a higher surface area bphe for the ground (glycol) side than the house (water) side.

That thermal conductivity is a big deal - inside the brazed plate heat exchangers there’s a thin layer of glycol that exchanges heat with the refrigerant, but it doesn’t mix or transfer it as effectively as water does to the bulk flow of glycol. Somewhere on the interweb I saw a paper on this - I think it was a factor of two overall. That is for example for a given heat exchanger size and pump, a 3degC drop refrigerant to water, or a 6 degC drop to a glycol mix. That 3C loss equates to a COP decrease. Of course, you can get a bigger heat exchanger to compensate.

We have an aqualisa aquastream, fitted 15 years ago maybe. The on/off/boost is controlled by delicate switches which sadly are positioned where any water drips might go - that’s all that’s gone wrong on it. Spare part was avail, easy to fit. People generally love it, plenty powerful on normal mode. Ours switches on with the bathroom light, to get rid of a bit of standby power without having to remember to switch it on and off.

Wiki has a page on this topic. There’s an HHV and LHV term for the calorific value of a fuel (Higher and Lower Heating Value), and they differ by about 10% for natural gas. HHV is what I think everyone would expect - the total chemical energy released on complete combustion. LHV is lower as it assumes you can’t get all the heat out of the combustion process! And guess what - LHV is used by the whole ‘natural’ gas industry. I suppose it makes for better numbers. The end result is that gas boilers are only maximum efficiency when they reach 110% 🧐 https://en.m.wikipedia.org/wiki/Heat_of_combustion

Totally agree measurement is more accurate than modelling! There are a few confounding factors: Was, like most, your existing relatively high power gas boiler turned on when you wanted heat, off when not? You are unlikely to be able to achieve this with a correctly sized heatpump - so it will be left on almost all of the time and the losses will increase a little. 19degC is ok for you now, but will others think so - and will you get the grant at this design temp? Generally +10% for every degC increase. The heatpump nameplate output power isn't always at the coldest temperature! I also don't think it takes defrosts into account. Ok this last one isn't your heatloss issue.

This just doesn’t match my personal experience. My parents years ago had a timeshare in a triple glazed highly insulated wooden house in the UK, which had hollow sounding plasterboard walls. It was build around 2000, I don’t know what insulation it used. Many evenings in October it was too hot (either due to cooking or solar gain), windows were opened wide for an hour to decrease the temperature. After a hot evening it invariably would be really cold in the morning, so electric heaters were manually switched on as it didn’t have central heating. We all appreciated how wasteful this was, but had no way to change the property to prevent it, and elec was not separately charged. Our retrofitted home now is similarly highly insulated, but has solid walls and floor, and the temperature just doesn’t change much over a single day - and we never heat and open windows in the same month let alone day.

We use Thermox DTX in our gshp groundloops at 25%. I found we needed it as the cold heat exchanger iced up once - I was lucky not to kill it😅. The header tank (diy, old school) ended up with a lower percentage and went a bit funny with floating manky stuff in it. I didn’t have any more DTX, so I sieved the header contents to get rid of the worst, then added half a bottle of fernox F7 biocide. That was a year ago, no more floaters, haven’t noticed any issues 🙂.

Knackered ballast maybe. Perhaps it has a few shorted turns due to old age and heat. The ballast generates the high strike voltage when the starter bimetallic switch opens - if it’s a bit tired it just won’t be quite high enough. You can often get led replacent strips now, they won’t need a ballast I expect - Ahhh, beaten to that comment 🙂

HDD generally has a "base temperature", which will affect the results. When considering how much heating your home will take to be comfortable, you need a base of maybe 15C - that's the outdoor temperature at which no deliberate heating is required inside. Ie you don't include accidental heating sources such as body heat, incidental electricity use, sunlight, cats n dogs. I think the subtly different question of: "How much energy is lost per year out of the windows" would need a base of 21C.