HughF

You’ll need to model this in heat engineer, heatpunk, or the freedom toolkit so that you know your heat loss for those required temperatures.

Your sap assumes 4.3 degrees for your location in the winter, which is a shit assumption. And the room temperature assumption comes from section 7, where the Mean Internal Temperature is shown…

Hardcore-> PIR -> bag -> pipes in 125mm conc… No need for screed.

Technology connections (YouTube) has done a great series on the humble air-air mini split, and why the efficiencies stack up, irrespective of how carbon heavy the grid is.

Isn’t this already a thing? So many GWh of offshore wind by 2035…. I work indirectly in the offshore wind sector and we’re busier than ever.

You’ll use less gas if you burn it in a ccgt and stuff the resultant electricity into a heat pump instead of burning it on site in a condensing boiler. No gas transmission issues, no gas risk in domestic properties. More renewables is obviously a good thing, but I disagree that we should be holding back on the rollout even though we rely heavily on ccgt.

And fwiw, as far as I can tell the only heat pumps on the market that don’t offer WC are the dream units from eBay, the occasional ground source unit, and swimming pool heat pumps.

What John said…. 3.5kW vaillant would be my recommendation.

I wouldn’t bother with that, it’ll be really un-technical.

My mate is a project manager, he’s just done it. You don’t need any pre-requisites, unlike g3.

Be aware that they are over specified, unlike Chofu/grant and others which will achieve output performance greater than the nameplate rating. Midea wouldn’t be on my list…

They’re all about a grand….

If you buy daikin, chances are you’ll be able to swap indoor units without replacing the outdoor. For generic Asian units that won’t be the case. A daikin vrf outdoor unit will happily drive wall mount, high-wall, ceiling cassette, or ducted…

F-gas course is 5 days and if you do c&g it never expires. I’m going to do it later this year.

You can ignore servicing with air-air, they’re basically unserviceable. Run it till it breaks then install a new one utilising the same line set.

I’ve been spending a lot of time in Northern Europe for work this year. Air-air units installed on balconies of flats seem popular.

R290 a2a doesn’t require any certification iirc. As long as the refrigerant charge is sub 900grams. Apart from the fact that the uk will end up looking like the back streets of Changhai, with a box hanging off the wall, I don’t think there’s anything holding the technology back apart from chronic lack of understanding by most people about how good they are.

Meanwhile, over in air-air land…. This would heat your average terraced house no problem at all… sunamp for the dhw, job done.

These photos show the single skin blockwork above the front door, the leaks through the letter flap, and the cast in situ boot lintel above that front window. These were taken in January.

Porch footings were poured a few weeks ago. We’re up to FFL for the porch now. That will give us the air lock for the hallway/main access door. We always planned to move the front door out to be flush with the front of the house. I’ll get a new/better door and fit it properly. As for the front lounge, I guess we can just do what we can. The heat loss is a toss up between ashp flow temp and rad sizing for this room. Wife wants the wall space, I want to put two 600x1500 type 22s on the wall. I think it’s able argument I won’t win.

Not the first SAP I've seen where they calculate the heat loss at un-realistic outside temperatures. I'd be happier if they used -2 or something instead of 4.3 degrees for January. Anyway, you need around 2.4kW to heat this place when it's 4.3 degrees outside and you want 18 degrees inside.

"Yes the Ego is an ideal unit for heat recovery within a wet room. This unit is only really suitable for a wet room as it does have an automatic boost mode which can be loud (noise similar to an extract unit). This would not be a suitable unit for habitable rooms such as bedrooms. The E260 is the unit suitable for bedrooms, this unit works in pairs. As an example; with one unit in Bedroom 1 and the other unit in Bedroom 2 they alternate between supply and extract every 70 seconds. They use a centrally located controller. The Ego is priced at €1,311.18 inc VAT. (This price includes the Ego unit, duct pipe, controller, transformer, internal and external grills) The E260 pair is priced at €2,063.94 inc VAT. (This price includes 2 E260 units, 2 duct pipes, 1 controller, 1 transformer, and 2 internal and 2 external grills)." "Oh I understand now. Unfortunately, we don’t have a heat recovery unit that would work on its own bar the NexxT unit. But the Nexxt is a large unit at 500mm x 500mm. The Ego is more suitable for wet rooms. There is a Silvento unit (also more suitable for wet room areas)… and would be extract only and not heat recovery." Some relevance to this thread, so posted it here. This was a discussion I had over email with Partel this week.

240mm here in the extension... funny how the levels ended up

This downstairs, front, room faces north. Both Heat Engineer and the Freedom Heatpumps toolkit give the heat loss at around 1200w. We're looking at changing the window for 3g, removing the thermally bridged sill, insulating the suspended timber floor and lining the north and east (against the alleyway) wall with insulated PB. Apart from that, I guess there isn't much else we can do to get the heat loss down to something more manageable? The walls are already blown with chopped glass/mineral fibre.

My 150ltr slimline has zero parts on it apart from a 3 port... It's as generic as you can get.