joth

Nice write up! "the ASHP is set to require a dry contact (between terminals 24 and 25) on the control PCB to activate cooling mode" That's quite funny you had to disable this dry contact option - it's a nice option to have, and I really wish the ecodan FTC6 supported this as then I could have my home controller (Loxone) automatically switch the unit between heating and cooling as needed, rather than have to do it manually. Still it only needs toggling twice a year so I'm currently OK living with that.

Quite! I wouldn't put much faith in it... Although, I do know one person that successfully got an entire system replaced after the original was mis-specified so it is worth more than zero

Fwiw it also means you have a warranty over the design and theoretically industry backed recourse if it doesn't perform or the supplier goes out of business. It may also provide better support/warranty from the manufacturer. Along with avoiding the need to learn how to join pipes this was enough for me to pay the slight premium but totally get for someone more time rich/cash poor the equation would look different. Having choice is useful, which is what smarts about grants and vat reduction incentives tied to taking the "luxury" of supply/install

You originally mentioned running 10kW HP for 8 hours each day. This won't work in cheap rate window! Likewise 16kW for 5 hours may work in economy 7 but rules out octopus Go (4 hour at 7.5p/kWh). So you'll need to go as large as you can if you want to optimize for cheap rate electricity Fwiw we have a 8kW ecodan (160m2 passivhaus) and run it for 3:30 or less each day on heating and then 30mins DHW to fit into Octopus Go cheap rate. On cold days I have automation that sets the UFH flow temperature very high then backs it off as the in-screed thermistor heats up, to ensure I get maximum utilisation during the cheap rate (even though this reduces COP, it works out cheaper due to the tariff)

LOL. I bet it's a website error then that they never intended: no longer checking partner status before offering the prices. h/t for posting in the Google group, that's where I heard this from

So Loxone are back selling direct to consumers again https://shop.loxone.com/enuk/ Not sure what to make of the policy flip-flopping, but this is good news to me as if anything does ever break I know I can order it direct from them for delivery ASAP if needed.

Just to check, do you need a CO alarm? I.e. you have gas appliances? We went all electric and didn't bother with a CO alarm

OP says water already switched to electric and implies the ASHP would only be for space heating. I assume this installer's 10kW guess is just for guideline pricing? If they do an MCS supply and install they're obliged to do the room by room calcs so would in theory find any shortfall and upsize the unit then. But I personally would not have any confidence in that 50W/m2 guess so would get some more quotes first!

Is the FiT managed by Octopus too? In my experience getting the data through to the online dashboard (on Octopus and Ovo before that) was a bunch of work. The in-house display, the dashboard, and the billing systems all seem to be independently managed.

What SEG do you have for export (if any), and is it with octopus? We're on Octopus Outgoing and Octopus Go. Our in house display hasn't worked for years (since we asked for a meter move that they did as a replacement but never paired the display). But the online dashboard shows both import and export. However, I don't get paid for export automatically. Every so often I email their support and they manually copy my export numbers to the billing system and credit my account. Apparently "Octopus Outgoing and Octopus Go" is not a supported combo, I should never have been signed up into it, and hence the billing systems don't jive together

To clarify, the OP doesn't own a ASHP yet so this is not empirical data from measuring an installed system. The OP's method is to calculate the output heating energy demand per day (80kWh) then divide by the COP (assumed a hypothetical COP=4) to get the primary energy demand of 20kWh per day. This is the integral of voltage * current over the day. so it could be 10amps at 200V for 10 hours, or 1 amp at 20,000V for an hour, or any other mix. It would depend on the specific ASHP selected and installation environment. (obviously 20kV heat pump is ludicrous but the point is for this stage of the paper exercise, the specific current and voltage don't matter, so long as the integral of power over the day can meet the goal)

Very close, your maths seems good but your units are garbage 😅 There's a serious difference between kWh (energy) and kW (power) and you can't interchange them. LMFTFY: boiler is 17 years old so assuming 80% efficiency and read 1L oil approx translates to 8kWh of energy so 10x8=80kWh? So I need an 10kW ASHP on for 8 hours or 16kW for 5 hour’s continuously? ASHP has a ratio of 4to1 so cost would be 20kWh a day

A quooker tank is about 10W heatloss at 100°C I think very approximately this means the 7L version looses about 1°C per hour (when near boiling)

It depends what material you are talking about. In terms of kWh I agree turning it off overnight has little difference, but as I say I do it to shift time of use to lower cost (both financial and CO2) times of day which does have a (small) material difference

Our one (Quooker Combi) doesn't have an on button. I just power it on at the mains and it's ready to deliver. (Obv not 100ºC if it's been off a while). My only motivation was energy/money saving, and it was very easy to do with the sensors etc already in place. The biggest saving would be when away on holiday, except there's someone in at least once a day to feed the cats so it still has a daily boil regardless. ---- I could easy program the automation to remain off during holiday periods or ignore the cat sitter's keyfob code for this purpose, except it's a combi tank so provides the kitchen hot tap too - or they might what a cuppa. I'm sure the legionnaire police also approve

Congratulations on moving in, and bigger congratulations that this is the biggest issue on your mind!! It must have gone well Our is controlled by the home automation so it only turns on when people are in the house and moving around. I also give it a burst at 4.20 am (last blast on cheap rate electricity) and whenever the solar is above 5kW or something. It is nice opening the door when coming home to hear the click of the kettle going on and the whir of the water mains stopcock open.

The channel for them was already routed into the frame, just outside the baffle. Lathems supplied the strips on request. Yeah we figured easier just to install them than argue about their pointlessness.

We bought some intumescent seals and installed inside the door frame. And an autocloser. Took photos of the lot and sent to BC and that was that.

That's exactly what my friend has. Basically same as me (same installer, even the same Oso geocoil UVC) just one size up ASHP.

Interesting, our extract vents don't have these, I should probably look into this. Is there anything specific needed to hold them in place or do the just sit loose above the adjustable vent? How do you replace them without messing up the vent position/balancing?

I asked a friend with the 11kW ecodan. Their house draws less than 100W average overnight and they can account for majority of that elsewhere, so certainly not seeing a high demand from the ecodan.

Welcome! The question is not just if it's adequate in practical terms, but also if it meets building regs and your stated goal of being as eco-friendly as possible The problem with old-fashioned vents is when it's windy outside they allow all the heat to be blown out of the building at an uncontrolled rate. Further, if you build with PIV and vents then there's no point investing time and money into building the rest of the house in a highly airtight fashion, being you'll have uncontrolled heat loss all over the building when there's any wind at all outside. That heat will need replacing by burning up wood at a greater rate than you otherwise would have, thus far from being as eco-friendly as possible. But if you build an airtight house, PIV simply won't work, and won't be signed off. And PIV requires an electrical motor running 24/7 so in terms of technology and electricity dependence you're already more than zero, so why not recover the heat too? I'd keep an open mind, you're very early in the process to be trying to optimize away a couple lengths of ducting.

Partway through there you jumped from talking about kW to kWh. Which do you mean? The line graphs don't help explain much as they are (non accumulating) kWh against time which is mathematically befuddled

My inverter (SE8000H) is the correct family to support the DC coupled battery, but needs a FW update that they've not yet released. (Currently only works with inverters up to 6kW, rumour 8kW support being added in the next ~month). Charging from grid during Octopus Go cheap rate is my main concern, but I'll report back here when I find out!!

Welcome! You're in the right place! You'll find plenty here to help. Definitely this! The main thing my smart home does is deal with excess heat (automatic solar shading, automatic stack venting). All the energy saving is achieved via high quality fabric first approach, no smart-controls needed.