S2D2

Yep sorry, SCoP. Edited for clarity.

Heat Geek state a guaranteed SCoP and will come back to fix the issue if the install doesn't meet this, or so they claim. Without checking I think all MCS installs should do something similar, Octopus seem to get around it by only designing for a flow temp of 50° so the stated cop is low anyway. Plus MCS won't actually enforce anything if they don't.

Be aware that you have to have a certain EV car or charger to get on intelligent go. They choose when to actually do the charge which is why they can offer such good rates. You can check what equipment is eligible on their website but it's quite restrictive.

This is a tricky one as I have it tucked out the way slightly rather than very near any seating. There are four fan speeds, I run it on three (four being highest) almost all of the time. I turn it down to two if watching TV in the room quietly. One is very quiet but I've never had the need to use it. None of them are silent but it's a consistent airflow noise that settles into the background. My dehumidifier is much, much noisier. I'm also running with a higher fan speed than is necessary for the room as I'm trying to heat the whole house with it.

Depends on the unit but the electriq one I installed claims no extra items required:

+1 for R290 unit. You don't have to vacuum it down as it can be flushed with it not being an fgas. Better if you do, but mine has been fine.

I replaced a 3B with the 5, nice improvement. Active cooling is annoying, my official case fan is a bit annoying, may be faulty. Pico WH connects to sensors via GPIO pins, I have one connected to a CO2 sensor. Powered via usb and pushes values with MQTT to the 5 via WiFi for logging. Very pleased with the Pico, it hasn't skipped a beat yet.

Yes I used 2.4x0.6m 18mm sheets, staggered joins and you screw the boards to each leg. No glue, didn't see the point and in case of access.

I think the question is less the OAT changing and more how much you have to push the flow temperature to get a reasonable extra amount of energy into the house in the cheap period, which has a larger impact on deltaT and so CoP. You can backtrack from the price to what an acceptable CoP drop is but I gave it up as too much hassle with A2A. I know others have had success with A2W and a big slab to store the extra energy.

I used loft legs XL (300mm) on the current house, really solid once the floor is locking them all together. Squashing 200mm insulation to 175mm would leave you roughly the same r value as 175mm insulation so it's up to you whether head height or the extra 25mm insulation are more important. When you say lots of rows, even with 600mm chipboard perpendicular to joists? Is the joist designed for it as that sounds like a long span?

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.