JohnMo

Way better quality, nice and thick compared to paper thin.

The things I find interesting The floor consists of UFH pipes in 56T of concrete. So a lot of stuff to heat up. Looking at this in a bit more detail Last time the heat pump ran it stopped at 0630. Sun came out at 1300. Flow and return temperature was slowly falling from the heat pump stopping (circulation pump stays on), and flow temp started to rise at 1400. The flow and return temperature started to rise 1 hour after the sun came out, all window blinds were closed as room temperature started to rise.

Fully inclusive billing amount including electricity standing charge and any Vat applicable.

I have a log of the temperature in the hall. Which is behind the rooms that get solar gain. Our lounge got to 24 peak, currently at 21.2 (5pm), dip in temperature is when I opened the door to outside (OAT peaked at 13 degs) and coincides with the hottest temp in lounge.

Just been looking at ASHP monitor system, it shows the flow and return temperature among other things. Sun has been out since lunch time. You can see the floor absorbing house heat. For context the UFH pipes are at the bottom of 100mm of concrete, the main rooms to get solar gain are covered in glued down oak floor or carpet. The ASHP is in full WC mode with no mixers etc and circulation pump runs 24/7. Rise in temp is 0.5 degs on flow and return (green/red line) over 2 hrs.

If you want a grant, otherwise buy a 4kW Panasonic - job done. Airtight done after second fix is complete.

I used this on my shed, not the best stuff. Have a look at proctor roof shield Yes, I just stapled No need to tape with decent membrane. Copper nail on top, if proper slates, if tiles batons are needed.

No - why not ask him?

But as he says, until air losses are tested MCS will only use spreadsheets values equal to a very leaky house. Needs his air test certificate in hand first.

Just recalculated it 14p per kWh, based cost paid to Octopus and total house electricity energy used from all sources. Just calculating based on the imported energy alone and total cost is 19.8p. The above includes my gas standing charge. Without gas standing charge It's 13p and 18.3p No smart meter, so E7 or standard tariff are available to me - don't get paid for export. Basing payback on a standard tariff of 25p and total house usage and what I would actually have pay, if no battery or solar, we are saving around £1200 per year. Total cost spent on PV and battery is pretty close to £10k, so close to 12 years payback, based on an awful PV production year due to rain most days.

Your 5% vat comes with a bunch of conditions, so check on HMRC website, some of the vat rules depend on if you intend to live in it etc. I may be wrong but worth 30 mins reading on HMRC website.

Well done, where there's a will....

I would be careful with the VAT implications to make sure you can claim it all back. Was there a good reason to do limited company and mandatory annual returns, accountant ect? And higher company borrowing interest rates?

Sorry where do you get that idea. You can live with and make an oversized heat pump work, but the ideal is a correctly sized one. Its very close to reality on our house and our summer house. Good to hear.

Just think your making a job very complex, just follow the manufacturer instructions. The supplement info for the outside sensor attached also. The simple wiring on the second section. With that I will get my coat. WB1B Compact Outdoor Sensor Instructions.pdf

I installed one, for the same reason. We use occasionally, have a mountain of wood to burn anyway. But house is on 24/7 WC, maybe may get loaded when we start to go sub zero.

Yes I realise your drawing is for the whole wiring centre, so is the Viessmann one, letter G representing the wiring centre, it has all the central heating system control, hot water control and interface with the boiler. Your S plan just says boiler stop start, nothing else. The Viessmann drawing shows a switched live through your room thermostat for switch box L terminal to terminal 1. Your drawing doesn't show any such connections. In fact your room thermostat is really doing anything? Dump the S plan and use the Viessmann drawing. Drive your 2x 2 port valves as suggested above via switch in one 2 port.

Your drawing looks way more complicated than the cdt box drawing

I paid £8k for 13.5kWh (usable) full MCS certified install a year ago and prices have reduced since then.

That's interesting, so slightly more than my simple E7 tariff. If I wasn't paying the standing charge for gas my figure comes down to 15p/kWh. But I assume yours is without battery? If that's the case having a smart meter (ours doesn't work) is a real money saver and would make a battery maths hard to justify.

Ours is just about the same, we have tiles and poured self levelling compound to level with the tiles.

No spreadsheet sorry, but info that may help, we run on just normal E7 (13p and 30p per kWh), and my total annual bill divided by kWh consumption for the whole electric (including a standing charge for gas) works out at 16p. Last year's heating season was a mix of trying to batch heat in E7 period and straight WC. This year doing straight WC. Dull, wet, cold day (no solar, clothes washing and drying) we end up running out of battery early evening. We are generally paying £40 less per month average with battery compared to without. 7 to 8 Deg daily CoP should be around 4 to 4.2, above that CoP drops slightly and it's more dominated by DHW and below that it's colder and higher flow temperature so drops again.

Good marketing trick, seems most have no clue how to operate a heat pump, and want to run like a gas boiler, should appeal to the majority. Make their running costs cheaper, but not sure they caught the idea with battery, multiple charge periods every day, run your heat pump on WC for peanuts.

Not sure it would be that good for that either, as @JamesPa says really a battery assisted tariff

That's why I moved from them, monthly bill kept going up even when usage kept coming down.