S2D2

Loft legs with tongue and groove chipboard are as solid as you'd need for loft storage imo. No need to glue which allows you to remove relatively easily unless you have many rows.

Go for the Arotherm plus, correctly sized and a very quiet, efficient unit. Without knowing more we can't say if the heat loss calculation is accurate, but the true value is likely to be lower rather than higher so the 10kW unit is excessive and likely to cause short cycling, lowering efficiency.

Will the eyes be drawn to the water cooler you've left space for instead? Sorry!

Which model heat pump is this please? What is your overall CoP so far? My A2A was defrosting once an hour at the worst conditions, heating air I guess makes it less likely to get stuck in "catch up" mode, but the gas boiler comes in more often as a result. I'm on Cosy with a home battery and just gave up messing with temps during the peak periods and let it run constantly other than in the peak period. There just isn't enough storage capacity with air even though the CoP hit was acceptable.

Smart meters are very accurate and best of all completely free to have installed, you've already paid for it whether you have one or not. To get good accuracy and usage breakdown (over what a cheap in line meter would give) from a consumer product you're looking at openenergymonitor emontx with a 100A clamp for around £160. You could compromise accuracy and do it cheaper with a home brew setup. But why when smart meters are available?

Missed the nut completely, mine didn't have one. Curious.

Yes, washer underneath like this not on top. Plastic bit spreads the load as tall taps can create large moments. Here's the one I fitted to a ceramic sink which does show position on install step, has similar nuts which act as the screws do on yours: https://www.caple.co.uk/wp-content/uploads/2020/03/KON3_CH.pdf

Not an issue if you want the increased capacity, but if you didn't need it running the heat pump 10 degrees higher is a big hit in efficiency no? This is an outstanding question for me, to fit one or not, so thanks for the experimentation!

Is the 50 degrees due to the mixing valve always allowing some cold through or for hot water capacity/legionella? Thanks for the write up, interesting as I'll be putting one in soon.

It's a rough way to get to the ACH value to use for heat loss calcs. Likely not linear so only applicable for "kind of leaky" houses. That said, modern houses that reach low values will be dominated by mechanical ventilation, so it's a moot point anyway.

0.3 for the heat loss calculation, not the blower test. Shows in the thumbnail that's after dividing by 20 and the actual blower test result of 6.4@50Pa

Bright give you access to the DCC data so would cover this period were you so inclined. There's others available but I haven't used them.

I'm regularly annoyed by this omission, I can do the opposite but why not both ways? To save pennies I guess...

Yes sorry I just assumed the video was the electriq unit but that's r290 so can't be. They look very similar!

Spin the whole duct 180 degrees and see what the reading is for the off centre position. Sounds like you have highly non-uniform flow due to a bend near the outlet or something. The longer pipe will help redistribute to a uniform flow, hence why turning the pipe around changes the value. Interesting issue to watch out for when calibrating perhaps.

Ah yes, that'll do it. I can see the attraction of small size and cooling capability, how is the noise?

Ouch, designer or just sheer size/quantity?

It depends how often you use the space I'd say. Efficiency when pushing the unit hard will drop but if the space is unused for a long time this will eventually offset and save more. I leave mine on 21/7 (cosy tariff) as I prefer the things in the house you're in contact with - seats etc to be at the right temperature, not just the air after a quick warm up blast.

Oh dear. Confused when you say it detects everything except R290 though, is this a different unit?

No.

It needs a heat loss calc but as you said assume insulated I don't see a 3.5kW minisplit struggling to heat the space at all. If you have a partitioned room you'd probably want a multisplit for ideal comfort though, I haven't seen a self-install R290 multisplit yet. Intermittent use of a separate space is the perfect use case for A2A but costs can build if you need planning and installation etc. Most efficient running costs though.

I believe he's talking about the all in one units which have two big air ducts through the wall, rather than minisplits which have a ~65mm hole and the noisy stuff outside.

R290 units don't require FGAS as the GWP is so low. A professional install would have doubled the cost of mine.

Keep going, this is not acceptable.

I think for DIY sticking to the pump/manifold for a vacuum test and using the provided mechanical connection is enough, unless you actually have mechanical damage to a pipe causing the leak?