Beelbeebub

Any idea why the Willis heater seems to be very common over there but almost never on this side of the sea? In GB an immersion in tank seems to be the norm for unvented electric setups. Is there some reason beyond "that's just how we do it"? Like some sort of odd regulation that banned electric heaters in tanks or something?

Pretty sure thermal stores are exempt from needing legionella cycles as they don't store the potable water at high temps, it's instantaneously heated on it's way through the coil

Am looking at a solar & battery setup. The panels bit is easy - as many as we can fit as they are cheap now. The harder part is the inverter and battery. We've had various quotes from different installers all recommending different brands! So far Tesla PW3 Sigenergy Sigenstor GivEnergy Solax Puredrive/Duracell TBH The powerwall has got a good rep but I can't bring myself to go for it given <gestures out of window> The Sigenstor looks good on paper (and physically) but is fairly new and towards the pricey end I've heard conflicting stuff about Givenergy and Solax but like the fact Givenergy is UK based I know nothing about Puredrive apart from they are apparently now the Duracell units and are also UK based Has anyone got any experience with any? Things like reliability, customer support etc

Slightly different environment but some trials have shown an increase in the agri output after the solar has gone up. Maybe shade helps with reducing water loss and keeps the temperatures in a more optimal range.

Can I check what the issue is with fitting the specified rads? Is it aesthetic? Cost? Space? I've had to replace the failed UFH in some of my upstairs rooms with rads, 600x1400 (or maybe 1600, can't remember) with a flow temp sub 40c (it runs same flow temp as UFH). They work really well, despite feeling only slightly warm and you can feel the heat coming off them and the room warms up nice and quick.

Am I right in thinking you are effectively having no heating in thr upstairs and relying on heat transferring from the ground floor and not having particularly warm bedrooms? I think the issue be the MCS rules state you have to have sufficient heating in each room to meet that rooms heat loss and they also set a temp for bedrooms at the design temps (migbt be 21c, can't remember) Those rads aren't that expensive (assume I assume k22's). Fit them then remove and cap off afterwards. Alternatively spec a higher flow temp to get smaller rads, then run at the lower flow temp (just make sure your UFH is spec'd to run at the lower flow temps, which it should be)

I did see a YT vid where the guy had fitted a small home battery system that was large enough to power his HP through the high periods (so maybe 5-10kwh) so that all his HP (plus a big chunk of domestic) was at the half price octopus cosy rate. That means your cop only needs to be about 2 to be as cheap as gas. Obvs need to invest in the home battery system.

9 is next to 0 so 0.3kw?

https://github.com/glynhudson/samsung-modbus-mim-b19n Any help?

Reasonable point, but does the HG thermal store provide similar hot water volumes? The HG mini stores that would replace a boiler are only 80l and the delivered hot water volume is less than that as the store can't deliver any useful heat once it gets below 40/45C I know they say you can run the HP at the same time to extend the volume but I don't think that would work in winter with defrost etc. The point abiut the bus grant is very valid though, which is why an adjustment so DHW can be via other means might be a good idea. This would make hybrid systems (which I guess this would be) and a2a systems eligible. Whilst installing a full HP system with a SCoP of 5.0 in every house would be the ideal, it's unrealistic. Heating is the majority of housing thermal demand. Electrifying that as much as possible would be a huge win and, as has been pointed out, a lot of boiler installs are "distress" installs where there isn't time for all the usual gubbins that goes with a "proper" HP install.

The HP would be for heat, the battery for DHW (in this thought experiment) So your HP would run pretty much as is on the cosy type tariff. The battery would run, pretty much as a cylinder would on the cosy tariff. The major difference would be a HP charging a cylinder draws less than a battery charging (for an equiv amount of hot water delivered) so there is a downside there. But the battery capacity could also be used to reduce the demand on normal and peak electricity. Remember this stems from the idea of speeding up and simplifying the install by not having to fit a cylinder. If you already have an appropriate cylinder then the disruption is zero anyway. But if your cylinder and piping isn't appropriate or, worse, you don't have a cylinder at all and just have a combi (say your combi breaks down and you just need a replacement ASAP). Then we get into the question of "how to replace a combi with a HP quickly and cheaply" the ultimate efficency can come later. Fitting some batteries (prob nearthe HP) and a high power boiler should be quicker and less disruptive than fitting a cylinder. Yes a 10kw inverter isn't cheap, but not super expensive either, under £1k is possible. Even £500. Fogstar sell a 15kwh pack for £2.5kish. With a £500 inverter and a £300 boiler you are talking £3.5k for the kit to replace a combi with very little disruption inside. Add another 4k for a 6kw HP and some fancy controls to utilise the existing rads as well as possible and we have £7.5k of hardware to swap out a combi boiler without doing any work inside bar replacing the existing boiler box with an electric boiler and Adia hub. The cables and pipes exit via the flue hole to the batteries and HP outside. The only other inside work might be a chunkier cable to the "boiler" from the fuse box.

The 2h window is just before midnight and then there is a 4h window just before "getup" time so most households would have 6h to charge. But regarding power draw, the situation would be no different from an unvented cylinder. That can only charge at a specific rate, usually no more than 6kw (2 elements). Often only 3kw. Except every bit of energy you put in can be transformed into whatever temp water you wish. Plus the standing losses are near zero, so even if you charge up your battery with 10kwh at 4pm, there will still be 10kwh to use at 10pm. Cylinder losses are typically 60w so about 1/3kwh in that same time. You also have the possibility of variable charging rates. So your system can monitor your overall draw and modulate it's charging rate to stay under your set limit. So if you put a kettle on, or the dishwasher kicks in, your battery can reduce it's draw.

Yes they do. I reread my post and the units were correct (aside from capitalisation - which is an artifact of using a touch keyboard making capitalisation time consuming)

Isn't the point that a UVC stays relatively well stratified when discharging so if you have 150l of 65C water you get most of that at 65C before the last little bit drops off due to mixing? This was one of the arguments against thermal stores for HPs. Yes, a good chunk of batteries only output 0.5C ie a 10kwh battery only puts out 5kw, which would mean having to install (and pay for) a larger capacity. This does make the economics a bit worse. But a larger battery of 20-30kwh would give enough storage to run a HP through the peak periods meaning it would be plausible to install a 20kwh battery, 12kw HP and 10kw instant boilers. That may be alot quicker to install and every day is £750 in labour minimum. 3 days saved coukd be £2k plus saved on the install which is a good chunk of the materials difference

The sunamp is an option though that would have be installed inside and they are super heavy. Cost wise they are about half way between a cylinder and a battery. The batteries can be installed outside or anywhere really and can provide more functions than any pure thermal storage solution eg uninterrupted power supply, time shifting all electrical demand, solar input. As has been mentioned it could also get around the "cold leg" issue for large/awkward properties. It also offers the possibility of easy increace in hot water storage by simply adding another battery The key thing would be to get the BUS grant to apply in cases where the HP isn't the sole hot water source and/or to reduce the price of batteries.