joth

Your numbers look right. MCS uses an "Air Change Factor (W/m³K)" of 0.33 which is basically your 1.25 kg.m-3 * 1 kJ.kg-1.K-1 in watts. Then multiplies that be (volume x delta-T x ACH). The empty MCS calc can be downloaded here if you'd like to play more 😄 https://mcscertified.com/wp-content/uploads/2024/12/MCS-Heat-Pump-Calculator-Version-1.10-unlocked.xlsm Basically, it's a very big room.

Agree -5°C seems low for a design parameter, but also I can't see how it's consistent with other energy loss rates from the same table. E.g. for the external walls we have 99÷(0.15×20.5×2.3) = 14 K delta T. Which yields is 7°C OAT What gives?

OK super useful to know. I'm about to pull the trigger, but want to confirm that i can get export with them too. Looks like I should be eligible for the 16.5 "Next Export Exclusive" which is 1.5p better than I have with Octopus https://www.eonnext.com/electricity-and-gas/smart-export-guarantee clearly EOn on a major customer share land grab; I'm sure these prices will revert in a year or so, but seems worth making use of in the mean time. I've looked at the EV again... about 10k£ to upgrade for a similar estate car to our ICE (well, definitely downgrade in performance, 280 down to 160bhp, and lose AWD and a foot of boot space) which will take 8 years to payback, as we only use it ~5000mi per year. Hmm

This is very interesting. I'm on Octopus Go, which recently increased from 4 to 5 hours, but 7 at a lower rate again would be very useful. I can almost certainly stop driving the heatpump so hard during cheap rate and still meet daily requirement from the cheap window. How strict are they about EV ownership, and how do they verify it? I fully intend to get one someday but it never seems a priority or justified.

Yeah, if the ASHP is driving ufh only then you don't really need mixing valve. Is it adjustable? Else you're just stuck with whatever it is set to

This comes up every few months. Probably more now it's winter and working harder Here's my experience Despite all the advice to the contrary, after trying everything else I just disabled the flow sensor dip switch and it's seemingly been working fine ever since... I'm trying to get hold of a replacement sensor to swap in and confirm if it's the fault. Unfortunately they're expensive and hard to get hold of 🫤

You can't use a double check valve or similar as there's not guaranteed to be enough pressure in an overflow situation to open it. Drains normal stop back flow using gravity, that's essentially what the standpipe is for in your setup, and in a washing machine outlet, and the tundish mentioned above is essential the same idea. The problem is water softeners don't have much vertical drop hence the very crammed standpipe and risk of it filling up and syphoning back. Our softener is installed on a meter high pedestal to give more drop

Just to clarify, I also think it is condensation. This normally forms at the coldest spot on the wall/ceiling, and a thermal bridge is most likely cause of such a cold spot - hence my question. (I wasn't meaning to suggest there's a penetration that moisture seeps in through, just any break or simply a thinner patch of insulation would be prime cause of a slightly colder spot )

Are there any penetrations through the kingspan that maybe creating a thermal bridge? How is the membrane and plasterboard supported? You could get THERM modeling done to identify thermal bridge condensation risks, but that's normally pre build activity. A thermal camera maybe quicker and cheaper at this stage, especially with some nice cold days coming up

No refrigeration pipework makes self install much easier

For ground floor install that makes sense but I think a lot of attraction on the DIY install is that can be done on any story of a building with no external works needed. (I'm struggling to remember how the external grill is installed and made good from inside, but pretty sure I saw video of it being done) Then just plugs into a wall socket.

Normal method is to search for a socket with three cables, but yes old house it maybe a hidden junction anywhere. An existing FCU should be obvious, as you'd need it accessible to replace said fuse should it pop. I think safe to assume there isn't one. Even if you can't find where the spur is Tee'd off the ring you seem confident to know which socket is first in the spur chain? So you can put a FCU co located with it.

How far is it from the consumer unit? If you're decorating soon then getting a new cable chased in from CU to head of the spur, to convert to a new radial curt, before you decorate would be best. But obviously only works if it's near enough CU to be practical. Else a short term fix would be insert a fused spur box (or even 16A MCB) at the head of the chain to protect all the cabling downstream from that point. Still far from best practice but an improvement on what you have.

Have you got two-way audio setup with the reollink? I didn't know this was a thing. Apparently Reolink is the main (only?) device supporting it over open protocol (WebRTC, integration via go2rtc) https://docs.frigate.video/configuration/camera_specific#reolink-doorbell If your issue is reliability of their wireless chime maybe you can work around it using the visitor event in home assistant to chime a convention hardwired ding dong chime? https://www.home-assistant.io/integrations/reolink/ For 76 squid their PoE doorbell looks great value. Just lacks the NFC/fingerprint tech vs unifi Protect

.... which is much less effective than dumping cold air on top of the body. EDIT to add: in addition, blowing air gives will windchill effect of its own. So even if the air it ~same temperature as the room it can still create a cooling effect.