joth

Ideally a TIA CAT6a certification test (while drawing full load on the electrical equipment sharing that trunking, which if PV might mean doing it on a sunny day lol) But if this wasn't in the original contract I can see them at most giving you a basic cable verification (buzz) test https://www.fullcontrolnetworks.co.uk/questions/copper-cable-tester-your-options/

Late reply, but that trunking is not ideal for CAT6a cable feeding the whole house, as a) there's not going to be much space in it if you have 96 cables as some here suggesting LOL. (Or even 50 cables) b) it's generally not considered best practice to run data and mains together in parallel Not strictly a regs violation and CAT6a should be shielded to minimize interference issues so you may be fine, but if anyone designing from scratch I'd recommend splitting mains and data to separate trunking

What is the heat source? Gas combi, oil, ASHP? What are the floor finishes? End of day if you don't care about increased running costs go ahead and install it per contractor's recommendations. It'll take many years of reduced bills for the huge cost of dig out and reinsulate to pay back. Using minimal floor finish like amtico will promote as much energy as possible to come up into the room, and is less prone to damage from the higher flow temperature you'll need to run. But keeping with radiators will be much cheaper to run.

Yes, I made this mistake too - thought 4x2m would be plenty for plant+washing/util+cat feeding but it's way too small. Having 2 doors into there (access through to garage) doesn't help. Also I think I'd push a bit harder to get the laundry in the upstairs fam bathroom (or adjoining it). In addition, I regret going with plasterboard and 25mm service void in the plant/util room. It would have been much better with ply-lined walls, no service void, and have all services in surface trunking. I've tinkered with so much of the ASHP since install (3 years ago) this would all be much more robust without crumbling plasterboard. Finally, putting more effort into coordinating the layout of manifold/UVC/ashp pumps etc - The installers put the all in rather haphazardly again not making best use of the space. Other than that, the main thing I'd do differently next time is demolish and rebuild rather than deep renovate, perhaps doing something more ambitious with planning like upside down house, if the plot suited it. (Our current house really would work nicely like that, enclosed bedrooms on GF and nice views across road to the common on the FF). This is not so much a regret of the last project: on balance I'm far happier we cracked on when we did rather than drag out a couple more years on the design and PP for a rebuild, but if doing it again, a clean sheet rebuild would be the main motivator.

Hmmm well 10 weeks running it with the flow sensor disabled it seems to be performing just fine, so I'm still inclined to think it's a sensor failure. Ideally I'd borrow a replacement to test - they're not cheap, and a bit of a pain to get hold of. I only really need it to get more accurate energy delivery estimates from the controller.

Welcome! Another Hertfordshire based self-builder here. I did a deep retrofit in Harpenden in the pandemic, and been helping with M&E and home controls for a number of friends on self builds since then - happy to have a chat on local options for this if you're nearby, feel free to DM me. If I am reading this correctly, from the elevations this is a 3 story build but includes plans for 4 floors - It looks like the first and third floor plans in the series are alternative options for the "middle" bedroom floor: one with w cavernous placeholder "storage util" room, and the other with it built out as a cinema and safe room. So in fact it's a slightly more modest 4-5 bed house?

I'm using a Carlo Gavazzi SSR with phase angle switching (0-10v comtrol) driven by Loxone. Runs cool and no issues so far 4 years in. I see they even do versions with modbusTCP control which would be even easier integration to home assistant

My experience for passivhaus (N=4 now) is 1/ never plan for "no heating" - seen this in one, the regret (and cost and disruption) of not laying UFH pipes is real. (I advised they should but by the time I was formally employed, the floor was already poured) 2/ a building wide model (e.g. PHPP) is just fine for heating - so long as the heat emitters are sensibly distributed through the area 3/ room by room is more necessary for cooling requirements than heating requirements - especially bedrooms

Wet UFH everytime Worst case is you don't need it, but it's relatively cheap to install the pipes anyway during build vs virtually impossible to add them when you find out you should have done later. This logic holds regardless of sap, phpp etc.

>To be honest what mostly let's us down is the gym/garage door That's not so surprising then, although what is more surprising is that the garage was included inside the thermal envelope at all, at design stage. As a garage you certainly wouldn't and even as a gym, I wouldn't expect it needs to be at the same temperature as the rest of the house. Can a more airtight boundary be made between garage and house - especially around any connector door? While it may not make difference to the bottom line airtightness figure, it may make a big difference for heating efficiency in practice. The thing about needing to know to do 2 tests is something every architect / builder / TF supplier / MVHR supplier _should_ know and convey to you. It's just a shame very few would. But to add to others already did say - very impressive build and such a strong attitude you both carried through it. Not easy to come through it unscathed - I know!

This isn't compliant with part L though is it. That requires at least 2 zones (and recommends one per room, which will be where the OP's installer is getting that from)

Yes, as 2 zones, the ecodan FTC6 controller manages all this, you can set each to a different flow temp and (with the correct electric mixing valve) it will temper down zone 2 e.g. for UFH. Although if it didn't, I have Loxone home control system and that can manage a mixing valve too, to make effectively unlimited zones of different temperatures. (I'm using Loxone to calculate the flow temps using weather + load compensation, and it pushes them to the ecodan FTC over modbus)

Note the wires don't need stripping before inserting as the crimps include simple insulation displacement. So you just need enough flex to strip off an inch of the outer jacket But my suggestion is also partially tongue in cheek, it's the cheap and quick potentially weatherproof fix (the gel is like vaseline in keeping water out) but clearly a bodge. Almost most of the BT copper wore telephone system runs on them...

https://www.google.com/search?q=Gel+crimps not the toughest google... I normally get the tlc ones https://www.tlc-direct.co.uk/Products/GPJC2C.html you'll need 8. you maybe able to find a little waterproof junction box for the lot

Snip the connectors off and splice the cables together with gel crimps

Reflects my experience. Originally I ran the FCU on its own, to "blast" the bedroom cold before bedtime. This had to be below dewpoint flow temp (below 7) to minimise the ASHP short cycling. But it still did a bit. I then added the volumizer in series with it, and programmed Loxone to run as much ufh loops as it can (ie in all rooms except any that are too cold) and for a longer runtime, and it doesn't have to be below dewpoint. But, I've insulated everything that needed it so I can run it extra cold if necessary (in a heat wave, and it's not been running for some random reason). But still I prefer not to run it cold as even with all the insulation I find random corrosion on the pump case bolts, the water diverter, etc. basically all the standard UK wet heating ancillary components aren't designed to handle condensation.

I know it sits uncomfortably as a tech consumer, but for ASHP in my experience it's much less about the brand of the equipment (within reason) and much more about the quality of the install. If you can find a reputable installer in your area that can do the design and come back a year (or whatever) later and do a high quality install, then yes, trusting them to select the actual kit used is probably going to be just fine. Also in the timelines of most (self) builds, the "best" option can actually change as ASHP is still fairly fast moving. pretty sure this is a new company from some of the fragments of the old Enhabit team (before it was acquired by GBS) Yep... Patrick Chester is the director of the company, same name as the chap that designed our MVHR install at Enhabit. Kasper who used to do their ASHP designs (and did one for also, although we went elsewhere in the end) also has his own company now: https://www.nextstepheating.co.uk/

** ..and lots of insulation / condensation management... Good luck, however it goes!

One challenge with this is it will require high voltage DC (i.e. higher than 50V so not SELV), which while not a problem in theory, is a bit of a grey area for most installers as they just won't know what regs apply. Camper/Caravan gear seems most likely place this would emerge but it will be a challenge as they tend to be only 12V or mains AC. I found this: https://coolmach.com/roadmap/ - if it gets beyond vapourware stage, then delivering 4kW output would imply around 100A @ 12V input (COP of 3.3), which just doesn't seem practical. It's unfortunate camper leisure batteries don't typically get installed at 24V or even 48V. Or perhaps camper architecture will change to collocate leisure batteries with the aircon (and water heating) gear which would enable this better.

I run the condensate drains into the nearest bathroom waste stack. Put it through a dry-running trap and down the drain it goes. Not sure why you'd want it in the plant room specifically. However, as said above if you run the ASHP just above dew point and can still avoid short cycling (e.g. by running UFH+FCU together no zoning) then you can probably skip the condensation drain altogether.

If you are happy to self install (or can find someone else competent enough to do it professionally) this will work, just bear in mind if doing it above dew point it's much more of a low-and-slow cooling power rather than the icy hurricane-on-demand you can command on an a2a. And always run UFH+FCU together to minimize short cycling.

Those are great diagrams of a simple concept I've explained many times in words and bad pictures haha Do you have a link to this knowledge base? Thx

Ha OK actually read the OP now, rather than just the post I was tagged in @G and J is this a 2-story building, with bedroom(s) on the 1st floor? Don't underestimate the effort it takes to add one FCU to an otherwise simple ASHP+UFH install. If you run the FCU on its own, it will have a much lower emitter size (and water volume) than the UFH so you're very likely to create short-cycling on the heat pump. Further if you run it as 2 zones you'll now need 3 circulation pumps, low loss header and electronic mixing valve (per Ecodan MIs at least, fairly typical) vs just one pump directly driving the UFH. And you lose some amount of cooling when the system switching to DHW and back. And you have to meticulously insulate all the ASHP pipework to avoid condensation (or only run it at 15+ degrees, which looses a heck of a lot of the cooling capacity which in turn increases risk of short cycling) If doing it all again I'd look very seriously at adding a separate A2A system for the bedroom. While it maybe a bit more in materials, it really isn't that much, and the installation cost may actually be less simply because it's such a well known process to install a mini-split a2a. Can still use the ASHP for slab cooling, but this is then a very simple control system. And this way you get two separate systems so still have some heating/cooling even if the other breaks. Worth a look at least

That quote about Mitsu vs Panasonic is 5+ years ago so no idea how it applies today. I've worked with 4 different Ecodan 8.5kW installs though, so can vouch it works fine for cooling. Another Daikin option is now available here: https://www.oceanairuk.com/product/daikin-fwp-2-pipe-medium-static-duct-fan-coil-unit-2-61kw-6-47kw/ It's actually the FWP-CT now, not -AT. (I swear these manufacturers much change model numbers more frequently than they sell units lol.) This is the MSRP for the naked 2-pipe FCU, just takes mains input and (I believe) a 0-10V signal to control speed -- it's inverter driven so very fine grained controlled over speed vs the old 3-speed coils, which is great for anyone like me integrating it with advanced controls (e.g. Loxone). Per JohnMo comment, I put separate thermistor on the flow pipework to shut off the fan if there's a slug of warm water in the pipe (i.e. when switching from DHW reheat back to cooling) But agree with Dave Jones that putting a concealed ducted unit is a lot of extra work, and especially so if retrofitting them like I did. If you can figure out a plan for the condensation drain and don't object to the aesthetic, wall mounted is a much more sensible way to go. The unit is actually inside the room being serviced, so ~100% efficient whereas the ducted ones always loose a bit of efficiency to air leaks, and the pipework and heat exchanger itself sitting inside a non-serviced space.

Was on glycol but added anti-freeze valves a year ago and I believe all glycol will be out of the system by now. I've had to drain and refill it several times due to other things going on. (Adding FCUs, adding volumizer, adding more bleed valves, probably something else). When I washed through the system filter (fernox tf1) the discharge was perfectly clear looked just like tap water. When I last filled it up last (Nov 2023) I put some misc inhibitor in (Sentinel X100) as there's no glycol to act as inhibitor. That's rated down to -2.5°C. the water never drops below 10°C so can't see that would be causing an issue. But, the gradual decrease in flow since May does corelate to the start of cooling season. If I can limp through to autumn it'd be interesting to see if heating-only mode undoes the problem. Otherwise I'm wondering if there's a strainer somewhere else in the system that has got clogged. Maybe on the external flexi pipes. Also to clarify the flow sensor (and the L9 error) are just on the primary circuit, which consists of: ASHP, pump, filter, 3-port valve*, LLH/UVC So issues in the zones (UFH and FCU) shouldn't impact this flow. * - the 3 port valve is a mid-position valve - yuck. I bought a diverter valve ages ago to replace it with, but when I went to fit it last week I found out I'd ordered 22mm but need 28mm. (The UVC is in 22mm which I measured, not spotting the reducer right where it enters the valve). I've just received the correct size 28mm diverter and plan to install, but this was mostly to reduce my suspicion that DHW/cooling switch over was losing efficiency due to a sloppy mid-position valve change over. I don't think it physically could be the cause of a reduction in flow rate.. But who knows.