Crofter

Love my vaulted ceiling. With MVhR the house doesn't get much dust or cobwebs. I have a couple of beams cutting across the space, I dust the top of them maybe once a year. It seems a slightly extravagant use of space but it was only going to be a loft otherwise, so why not put it on show.

Yes it's a completely off grid system, with mostly 12v loads and an inverter for the AC stuff. I was amazed that I was able to put together the battery for so little money- considerably less than the traction batteries I had been considering.

It's hard to beat a DIY approach for LiFePO4. Get the cells and BMS from Alibaba (other vendors available), top balance the cells, and hook it all up. More configurable than a ready made unit, easier to repair if e.g. the BMS fails, and cheaper overall. I'm not up to date with current prices but two years ago I built a 270Ah/12v pack for £407 including the BMS, shipping, etc etc. I had a few extras to buy but nothing much.

Obviously it depends on the car but I've certainly seen this one debunked. Electric is simply a more efficient powertrain than ICE, and even with transmission losses tends to come out ahead. And of course you get the benefit of removing the pollution from urban areas.

But in the real world you can't extract all the energy from petrol or diesel. An ICE vehicle typically only uses about a third of the energy available in the fuel. EVs are using 85%+

Ah yes I remember that program. They had a bizarre hated of plasterboard, and always tried to avoid it. Even though it's about the cheapest sheet material you can buy, and it's easy to work with, helps with fire control, and it's very versatile. I wonder if a genuine 'how to build a cheap house' program would really be popular, because when budget is king you just end up throwing out the nice stuff like big windows or woodburners. FWIW our build, completed in 2018, came in at just under £40k ex plot (but inc services) for 43m² usable. Almost entirely DIY labour, but I did have to pay VAT. I used corrugated steel for the roof and am very happy with it. Box profile might have some technical advantages but corrugated was within the vernacular here and looks much better. I wonder what my build would cost today?

That makes sense. I'd prefer to keep the outside unit(s) on the back wall of the house where nobody can see them. That would mean a minimum 4m run to put an outlet in the living room.

The distance between the outside and inside units would be about 2.5m, maybe a little less. The specs mention a 5m pipe length so I thought I'd be ok- am I misunderstanding something? And that's a good point about AC! Ideally I'd like a system where I can 'lock in' certain parameters but I'm not sure if that's possible.

@S2D2 just in case you didn't see it in the other thread I've attached the rough floorplan with the central A2A in red. It would be in a hallway so how well it works will depend mostly on whether doors are opened or not. One complication we have is we can't really say who is going to be in the house. It is our family home, but it's currently used as a holiday let whilst we're living elsewhere. We're likely to come back and live there again, but equally there's a good chance we may let it out again in future. The holiday lets are mainly over summer, so a somewhat undersized A2A might manage to cover the summer heating needs, and be far cheaper and more responsive than the storage heaters. I think the simplicity of a central unit might win out. We have a woodburner in the living room too which should help a lot in colder weather.

That's a great thread, thank you. I did skim it previously when starting to investigate this. I see you're finding it worthwhile despite being on gas. I'm on direct electric (storage heaters) so should see an even bigger benefit. Very encouraged that your COP figures are so high. I'm in NW Scotland which is not exactly tropical. But one advantage is that we don't actually get many frosts. What would your thoughts be on fitting one big central unit vs several smaller ones?

Researching A2A as a form of heating. E.g. slap one of these right in the middle of the house: https://www.appliancesdirect.co.uk/p/iqool24/electriq-iqool24-air-conditioner Seems too good to be true given the price. Any thoughts?

I did finally find, through a thread on here, that Appliances Direct sell them. Like you, I'm considering various options including a single central unit vs multi splits. I put some layout drawings on my other thread.

I'm just starting to wrap my head around the A2W and A2A options. Very early days. A2A does look temptingly cheap and easy to install! I've done a very rough sketch of the basic layout, then two different A2A installs- one central unit in the hallway, or two units feeding four rooms. For context, the house is currently used mainly as a summer holiday let (although we will be moving back in full time at some point). The smallest bedroom is only used for storage. The bathroom has a small electric towel rail. DHW currently supplied by a direct UVC in the cupboard. The north and east elevations of the house are completely hidden from view and would be by far the best places to put an external ASHP unit. S side may be acceptable but not ideal.

That's my bedtime reading sorted, thanks!

Thanks. How does the zero VAT rating work?

Hi, I'd be interested to hear more about this. Try as I might I can't find basic costs for A2A units online anywhere.

So I've done a bit of research on the rads, according to an online calculator based on T30 figures, I'd be spending about £750 on rads. Is T30 a bare minimum? Should I oversize? And on top of that I'm needing pump, maybe a header tank??

I've got a lot to research about A2A. So if I'm understanding right, you don't generally fit a central unit with ducting, but instead fit individual units for each room? I think my house would be suitable for most installations- detached bungalow with suspended floor and cold roof, so good access everywhere. I'm assuming I'll be going DIY with this, I'm reasonably handy once I've got my head round something, and I'm between jobs anyway so I have the time. Against that is the possibility of grants and interest free loans, which I have heard can be up to £15k in Scotland. But I'm assuming that, to be eligible, you have to jump through hoops and it would rule out the DIY approach. Haven't looked in to it yet though.

Just as a starting point, how about something like this: https://www.theheatpumpwarehouse.co.uk/shop/heat-pumps/air-source-heat-pumps/samsung-8kw-r32-monobloc-air-source-heat-pump/ I guess I then need oversized rads, pipework, circulation pump, anything else? On the DHW side, can I just keep my direct UVC and use off peak to heat it overnight? I guess that will cost more to run than switching to a tank supplied by the ASHP, but obviously it's a lot less work and upfront cost. Would be interesting to compare the numbers. I'd like to learn about A2A as well, so that I can compare the two options.

That's a great guide, thanks. Any suggestions for where to start on the ASHP/A2A side of things?

I agree, that would be the best solution. A couple of problems though- the house was built with T&G pine boards and they run under all the partition walls. So not a small job to lift. Secondly, I've not long laid laminate through about 50% of the whole area... not keen to take that up again! Fortunately, the access from underneath is reasonably good.

I'm happy to invest to get the ongoing running costs down. Switching to E7 would obviously be cheaper in the immediate term, but not a straight swap, because I still need to add timers to each individual heater.

By 'tackle', do you mean insulate?

Holiday let- so I'm still paying the bills!

Certainly not infinite! And complicated by the fact that I'm actually renting the house out these days, so it needs to be fairly idiot proof.