jack

Bad maths, meant a quid.

That's a 3 kW kettle element for an hour a day, or about £0.30 a day at current rates. Doesn't seem wildly excessive given the volume of water being heated.

I believe they only module down to a certain point though. If that point is too high, you could have cycling problems.

That seems high. Was that the building regs calculation? Our house is 289 m2 (with 2.85 m ceilings downstairs, a double height area, and 2.5 m ceilings upstairs, so probably higher volume than average for the floor area) and I think the BR calculation was 180 m3/h. In general, the BR requirements ventilation rate is far too high imo. I know that several people on BuildHub have cut that rate by half (or more) without any issues.

I generally run the MVHR at a fairly low default setting (80 or 100 m3 per hour, from memory) all year round.

Following on from my earlier comment about being surprised that it wasn't sweltering upstairs the night before last, I had the same experience last night. Back-to-back hottest days on record after a week of high and increasing temperatues, and it was still only a bit warm upstairs. Perfectly comfortable to sleep with a pedestal fan on low. I can only assume that by getting the underfloor cooling on early and leaving it running 24 hours a day for the last handful of days, the temperature upstairs hasn't had a chance to get out of control. It's a puzzlement.

Crazy. It takes hours for underfloor cooling to bring the temperature of the whole space down. 24+ hours would have been a better test period. Well here's the funny thing: I hadn't been upstairs during the day, and guessed 30+ based on the temperature the night before and the fact we had an incredibly hot day yesterday. However, when I went upstairs last night, I was surprised to find it only warm, not ridiculously hot. If anything, it felt like the temperature hadn't moved at all from the night before, and I'd be surprised if it was 30 degrees. Best guess is probably 26 or 27. The only things I can think that might have caused this are: it was overcast here a lot of yesterday, meaning solar gain was lower. I've had the underfloor cooling running 24 hours a day for the last three days, and that's having some impact on the temperature upstairs even though it's only directly cooling the slab downstairs. There'll be a small amount of cooling from the effect of cold air from downstairs mixing in the MVHR heat exchanger, but that alone surely can't explain the difference.

I run my UFH at 25, and it's only that high because I can't turn it lower. I have a small amount of weather compensation dialed in - from memory, I think it starts kicking in at about 7 or 8 degrees outside temp, and ramps the outlet temp to 28 or 29 degrees at around 0 degrees outside temp. I'm sometimes curious about what it would have been like to have radiators rather than UFH in an airtight and well-insulated house. That said, I certainly don't miss having big lumps of metal all over the walls!

I haven't watched the whole video, but how long did they allow the house to cool before deciding it didn't work that well? I don't have temp sensing, but at a guess it's currently something like 20º C downstairs, with a 16º C outlet temp from the ASHP. Coming in from outside feels like walking into a deep, dark cave. It got to 37º C here earlier today, and it's got to be over 30º C upstairs. Perhaps the cooling effect won't be so pronounced in a bungalow, given you have a warm ceiling immediately above the cooled floor. That said, even if you only get a 5º – 6º reduction, that could easily be the difference between a tolerable 22º C and an uncomfortable 28º C. I know which temperature I'd prefer to be sleeping in!

Ah, that sounds like positive pressure ventilation. Try putting this search term in google: positive pressure ventilation site:buildhub.org.uk Incidentally, positive pressure ventilation isn't considered MVHR, because it doesn't include heat recovery (= the HR in MVHR).

It's different for different people. For example, some think the forum is about unpaid volunteers giving up their time to help people. For others, it's about snapping at people trying to help, just because they don't like the answers they're getting.

I've never heard the term "insufflation" used in the context of building ventilation. Is this some sort of positive pressure ventilation system?

Looking at the manufacturer's code in the tech spec drop-down, I'd be surprised if there's any difference other than length: Odd that they're described so differently.

The surface area of the pipe exposed to the sun is less than that of the pool as a whole. You might be better off putting thick black plastic in the bottom of the pool, and maybe some bubble wrap on top of the water when it isn't in use. The heat is directly transferred to the water, so fewer losses and no need for a pump. Plus more surface area, so more energy. It might be more effective if you mount the pool on the PIR.

I half-heartedly looked into exactly this when we were thinking about how we would heat our house, but quickly stopped when I saw the results of the initial calculations.

I've always used: uk-water-softeners.co.uk Good prices and they do their own deliveries (although the delivery area is limited because of this).

I doubt you need to break solid rock down to the full depth, but there's likely to be a minimum depth of hardcode to ensure load distribution. Only the engineer responsible for the design can confirm.

I doubt you're the only one who thinks this, but I disagree. "Battery" has a long history of use in relation to thermal storage. Chemical storage devices of the type you're referring to are only called batteries because they're formed from a battery of cells.

Any home automation system that requires you to get your phone out more than once a week is a poorly designed and/or implemented home automation system imo. I rarely use my phone to control anything. All lights are on physical switches (but some of the switches do different things depending on time of day). Blinds are mostly automated based on time of day (except in the bedrooms), but also have switches for manual control. I've had similar, but generally waving your arms around was enough. It's worse in a large office unless you're willing to install lots of presence sensors. I mainly haven't bothered within presence sensing due to cost. Decent ones cost tens of quid, and the insane payback time means it makes no sense for me to install them.

Make the delay an hour or two from the last motion. You shouldn't really be sitting completely stationary for two hours, and a decent presence (not motion) sensor doesn't require you to run around the room to be detected. Another approach is to program the lights to briefly dim a couple of times shortly before turning off. If that happens, you can just wave your arm around to reset the timer.

Exactly. I think a lot of people don't realise how flexible home automation can be. For example, I have lights in some rooms set so that they behave differently after dusk (the HA system tracks the changing dusk time). If I'm turning the lights in the bedroom on during the day, it's generally because I need a lot of light. At night, the same switch just turns on the bedside table lights, because I almost never need/want downlights on at 10 or 11 pm (but can put them on with about 10 seconds' effort on the phone if needed). Even in the small number of rooms with just downlights, many are set so that the downlights come on at ~60% at night and 90-100% during the day. I personally don't have any lights set to come on automatically as a result of motion within a room. If I did use motion/presence sensors, I'd be more likely to set them so the lights still need to be turned on at the switch, but automatically turn off after some period of inactivity in the room.

Oh yeah, completely forgot about that!

Standby mode (in which energy is intentionally consumed to keep the components in the main signal path warm) is definitely something to watch out for. I have no idea how much power is involved, but I'd be surprised if it's less than a few watts per channel. As you say, across several channels in a home theatre amp, this could add up to a lot. It's true that non Class D amps are inefficient, but most amps are rarely if ever used at anything like their full rated power. Unless you're using inefficient loudspeakers and/or listening at very high volumes, you're unlikely to be using more than a few percent of the rated output most of the time. To be fair, this has completely changed since Class D amplifiers started making inroads a few years ago. They run at very high efficiencies, and when designed properly can sound excellent as well. Also, more expensive amps are more likely to use Class A output stages, which are less efficient than the Class AB output stages typically used by cheaper amps. Class A means higher power consumption for a given power output.

You had me going for about 2 seconds...

I believe there were several documented problems with the Immersun unit, at least in its older incarnation. Its design may have been updated since. Mine (bought about 7 years ago) died in less than two years, and wasn't covered under warranty because the original company had gone under and had its assets bought out in the meantime. My electrician installed several Immersun units over the same period, and then stopped recommending them after several failed in service. I think it's a little narrow-minded to reject an entire product category just because of historical experiences with one particular product. In the right installation, some units have a payback period that's shorter than the warranty period, so you have little to lose.