JohnMo

Some reading https://www.open.edu/openlearn/nature-environment/energy-buildings/content-section-2.3#:~:text=The key factor in determining,fresh cold air from outside.

To add to this, other countries, Germany, Austria for example, require a long detailed apprenticeship, to allow you to practice professionally as builder, joiner, plumber, electrician (in fact most hands on trades). Here many go through apprenticeships which are much shorter, they not compulsory. Here in the UK, anyone can call them self a builder or just about any trade if they want.

Ours were also HETAS qualified installers all Scottish based. Hetas say "Scottish Building Regulations do not make it mandatory to be a member of HETAS. However HETAS Registration may be a means of demonstrating competence for works carried out under Building Regulations." Scottish building regs say "The Heating Equipment Testing and Approval Scheme (HETAS) is an independent organisation for setting standards of safety, efficiency and performance for testing and approval of solid fuels, solid mineral fuel and wood burning appliances and associated equipment and services for the UK solid fuel domestic heating industry. It operates a registration scheme for competent Engineers and Companies working in the domestic solid fuel market. The Official Guide to Approved Solid Fuel Products and Services published by HETAS Ltd (http://www.hetas.co.uk/) contains a list of Registered Heating Engineers deemed competent in the various modules listed, e.g. for the installation, inspection and maintenance of solid fuel appliances. There are other organisations representing the solid fuel industry but neither they nor HETAS have a mandatory status. Either way, use of a registered installer demonstrates compliance to building regs and they have a much stronger position, than your none registered builder or individual, whenever any challenge is presented by building control.

Didn't realise it cost so much, I should have gone round building sites and taken it away for free, as we have just imported 750T, which we had to pay for.

You can always do a trial, a couple of days of lots of one-off and a couple of days on for two set periods and compare, the running cost and how long you wait for hot water

We used Speyside Stoves (NE Scotland)

You know what you want do, just do it.

Also some areas, like the whole of Scotland do not add Flouride Other area it come with normal ground water naturally added. Do they add Flouride in your area for certain? Bear in mind, the rain water you are collecting, is the same water that has just washed your roof clean, of bird crap, dead insects and pollution that has settled on your roof. It also has none of the natural mineral salts, so these may need to to added to your diet artificially.

The models Nick recommended or a Lowara Ecocirc Pro - same as I have. Inbuilt timer and thermostat. Set it to time periods you want hot water, i.e. when you get up until you go to work, when you get home until when you go to bed. It automatically circulates enough to get loop to the temp you set it at then maintains that temp. You're trying to invent a wheel that already made and available off the shelf.

No it's just the punched holes in the casing that you see on the link earlier. Think the holes are 4 or 5mm across

We were £2000 for install, that included slate hearth and full stainless double wall flue, trims etc.

I have one these, you would dramatically decrease the open area of the intake grill, the resistance at the intake could jump up. To compensate your fan speed would have to increase - more noise etc. The ductstore ones in the link have a much larger surface area, so get around this to some extent, but not completely.

But as I said above it has to be installed with unventilated air gaps either side of the insulation, as to get the thermal conductivity advertised it relies on low emissivity of the reflective coating.

Here are two photos of mine. J tube above footings, lintel in block work. We have a reinforced slab and the j tube is cast into position. The white box houses our meter. Once the insulation and UFH pipes were in, a further 100mm of concrete cast over again.

The Fluoride in water is food grade, so as I said be careful. Less than £300 new. https://www.directwatertanks.co.uk/1000-litre-new-un-approved-black-ibc-with-plastic-pallet?gclid=Cj0KCQjwnNyUBhCZARIsAI9AYlEJj9TG6haSFftXA4wExh_JOY5CM0uRwn0k6HJFNFolXVhtWMZq6WQaAtK-EALw_wcB

Biggest trouble is no-one installs it per the manufacturer instructions, with air spaces either side of the insulation. By the time you have the correct airspaces it's no better than much cheaper glass wool on a depth by depth basis.

Also hope you are buying them brand new never used. Many get used for all sorts of bad for your health stuff.

Read the manufacturers install manual that will give you the clearances and surfaces required. I would only have a HETAS qualified install, that way you get no questions from BC at sign off and your insurance if anything goes wrong later.

The 1m elevation will give you 0.1 bar uplift in pressure, which is nothing and really not worth any effort or expense. If you need pressure, you need to pump to an accumulator with a ranged pressure switch to tell pump when to start and stop, you need filters to take out particulate and a UV filter to kill and bugs.

600mm centres

Our non load bearing partition; 45x70mm w/w/reg treated timbers faced with 12.5mm plasterboard. Did noggins (if that's the right word) every 1200mm, walls are up to 3.6m high. Filled with 50mm dense Rockwool. Seem well solid.

That's what I will do with mine is there are any complaints. My duct actually terminates 400mm below DPC level but about 200mm above outside ground level, I will have decking above it. It is an L shaped duct the horizontal flows slightly downwards to the outside.

Got all mine from Outsourced Energy. Go to there web shop. No issues at all.

My sap EPC said 5kWh for 2.9 people for DHW. But two of us are using nearer an average of 7kWh. Looks like you only need a 2kW heat source for heating. Have you thought about UFH with Willis heater and direct electric water heating through E7. 2x 3kW Willis heaters (1 duty one standby) some isolation valves, circa £200 in parts. Low capital spend compared to heat pump. Direct E7 heating with PV diverter contribution.

Depending on size of house you may only need circa 3kW, the only ones I came across were LG and Vaillant