puntloos

Quick update: heating guy said he did indeed miscalculate and 80 is correct, will need to get different provisions than the MVHR for that cooling. @joth regarding the absence of supply spigots, apparently it stems from my wish to put the 1st floor FCUs in the loft (since 1st floor has no proper void). This meant the fresh air connections are connected directly into a return air plenum fixed to the FCU. The return air plenums are also connected to the two return air grilles by ductwork. If the FCU is off, the fresh air travels along the return air ducts into the bedroom below.

That was certainly my base plan, yes. That can still conflict of course. Hence the idea to have it 'all mitsubishi' so their single 'MEPcloud' app could control it. To be clear I'd probably go for loxone or KNX as the true brains (since I'd also have awnings etc) but the basic idea is there. Fair, but well, I think *normally* only one or the other device would work so the total running time of either would be split in half. I know that doesn't fully mitigate extra maintenance cost, complexity itself also means more stuff can fail. Good shout, hoping that the mitsu melcloud app would handle the 'simple situation'.. Yeah, it's a fair shout. It's funny how you end up in a place sometimes. - Start with standard boiler. Want AC for those hot days. - Learn about ASHP. OK, ASHP+AC - Learn ASHPs can cool. Nice. ASHP in reverse and done - Probably need a split ASHP since I was planning to put the device in the far garden, and water-based coolant runs are more lossy over distance - Hear tons and tons of people overheating in their cleverly designed passivhauses. (also- learn about 'global warming') - Hear cooling ASHP has a bunch of theoretical issues with condensation if not handled very carefully. - Hear joth and others have Fan Coil Units. Maybe that's an approach. - Learn that coolant-based FCUs are much more efficient than water. - OK so then I need a split ASHP that can handle a few FCUs too. - Nope, doesn't exist in UK market since I want R32 or better coolant (there is a R410 setup). Guess I need a separate device. So A2W ASHP and A2A ASHP. I guess? And here I am. Not saying I am in the right place necessarily but it's a logical path, no? ?

Ah! Interesting, yes, very much worth checking then. The math seems straightforward enough in theory (but completely haven't wrapped my head around it yet) - let me peruse your thread there. Oh sorry I guess I misread that part, I thought you figured the FCUs had to permanently be on, but either way, yes it's somewhat complicated but I currently feel there's a certain elegance in that both systems can work together or separately. Fair, thank you for taking a very close look.. Absolutely, that was the idea, in fact I would only tender for teams of "M" and "E" so also the programming of the 'smarts' is done by effectively the same team.

Small addition, the heatguy proposes https://library.mitsubishielectric.co.uk/pdf/book/VL-CZPVU-RL-E_PI_Sheet?model_query=VL-500CZPVU-R%2FL-E#page-3 (the 350 seems sufficient.. 500 probably better for buffer..) "Lossnay" - sounds like the real name is NLoss. Pig latin? People here seem more fond of Zehnder, but (so far) I'm an all-Mitsubishi farm. Not sure if there are huge benefits to sticking to one brand but as @joth noted, having all heat equipment talk the same language might prevent some battle royale while one thing is heating what the other is cooling etc.

So my heating guy says that it will require the MVHR to move 8L/sec to take away 1000W worth of heating whilst keeping the closet about 10C above living temp (aka say 32C), and on the other end it will supply 8L/s. Yeah, I've been aiming for 3ph I'm a bit confused, liter, as in total contents of the UFH pipes? Yeah I needed to be taught this (yesterday) that indeed doors are not airtight (I assumed so because of fire regs..) and you extract in wet rooms and put air into dry rooms. I was thinking the same but when I asked the guy said it was already done, perhaps in a more subtle way. He's been trying hard to hide most pipework in unobtrusive locations - under eaves etc, so I'm pretty happy with his designs for now. My suspicion is that the loft FCUs might actually be used as supply (an unpowered FCU, I assume, is basically a pipe, and there's one located in every spot where you drew your spigots..)

Spoke to my heating guy today. We seem to be mostly on the same page. Network and Projector cabinets You're correct, the idea is not to 'push' air into the MVHR - so no active fans added to the mix, but let it do its work normally - the only difference for it would be it would receive very hot air. I pointed out that perhaps 1000W is a bit much and he agreed it might need some more careful planning, will get back to it. Hot water buffer (A2W ASHP -> Buf -> UFH) Indeed, this will now be added, how big is such a buffer? Anyone have a link for the one they are using? (debating putting it above the DHW - since I have a high ceiling) Yes, we're aiming for the 8kW one as well. It's interesting apart from a minor price difference all of the sizes seem to be about the same cost, am I correct the only downside of having an 'oversized' one (say the 11.2 one) is that in low mode the minimum the inverter can run at is about 20% of max, (so 2-ish kW) which especially in the 'just heat a tiny bathroom tile' case it will turn onoffon? (plus you probably need 3-phase power, butI'll likely have that anyway)? A2A cost, value for money In my heating guy's view, it should be "about 2500 per device- supplied and installed" - so indeed the extra-over for my 6 devices (5 FCU, 1 A2A SHP) is 15,000 (and a bit for the planning approval..) - will see for tendering if this estimate holds up but in my mind if the extra cost of A2A is - say - 25,000 I would need to have a think but it still feels somewhat ok given the amount of extra flexibility, reaction speed, precision of heating location and overall redundancy. Fresh Air MVHR everywhere I don't think this is entirely true, in Bed 3 there is a supply, and I think there are often only one supply room and the other rooms are only extract rooms - only bed4 has no extract at all. (and the garage, arguably too..) My current understanding is that you would want to be able to draw a line from the supply through 'most places' and then into an extract, and with the exception of bed4 and garage that's the case? Hot water return We'll go the 'Joth' approach and put it in, but perhaps not open it up (and/or experiment) to see the pros and cons.

No - fair callout. But, to be clear, the work he is doing is quite limited, this is pre-tendering only, so this is a guy that came highly recommended by 2 separate sources and his only job is to do a rough design that provides a good idea to tender off of. Also, don't forget this is me 'channeling' the guy, and probably doing a poor job. So far his work seems solid if perhaps somewhat conservative.

Guessing here but I'd say that since the water gets pulled from the top of the tank, having the hottest water available for use makes calibrating a bit easier? Isn't this the principle that mixergy tanks claim are a good idea? And do you have a full hot water return?

Obv since this is not our own house I'm not sure what I can do here. I wonder if perhaps adding some rubber spacers might help with my particular problem. The creaking... interesting one. I suspect the landlord might want to retrofit this house once we move out. Sounds like a solution that could work, but there are also downsides to plastic plumbing, no? (not to mention health of water leeching chemicals in?)

Btw the reason my heating guy says no 'default hot water return' is that it could ruin the hot water stratification in the water tank. Seems .. somewhat logical? [edit] - looked this up: https://doi.org/10.1080/014576300271040 - the conclusion seems to be that if it's less than 3-tanks-a-day the disturbance should be minimal.

Doesn't sound daft at all, seems like it's omitted. Not sure why.

Not sure the designer likes asparagus. More of a broccoli guy myself. OK that's enough dad jokes for the day. The designer seems fairly sensible and at least came recommended. His entire quote on pressure: "Pumps are only allowed on the water mains if the water passes through a tank first (water regulations). This pump set is called a ‘cold water booster set’ and they can be quite large and expensive. I normally specify ‘Dutypoint’ https://www.dutypoint.com/ because they make compact sets, but even their kit is quite big. I recommend taking a wait and see approach, the water pressure is probably not as bad as you think."

Most water runs in this house are below 6m. The master ensuite has a loop at 12ish. I suppose it adds complexity. One silly question I have but the hot buffer is only for UFH I assume? Or will the buffer also buffer DHW?

To be clear, this includes your shower and bath taps? Do you get enough water pressure? My designer figures the added complexity and noise of pumps might not be worth trying to add pressure mechanically vs letting the mains do the work. Do you all have pumps to increase tap pressure?

I assume it's a loop too really, just that it will be only turned on by that movement detector, so to avoid the losses of a continuous running loop? But does your loop pass past some, most, or even all of your taps? Do you have any design example for that? Agree Yeah, it's tough to strike that balance. I'm perhaps over-steering on getting things done "while it is cheap" (e.g. during build time) rather than having to possibly retrofit things. One thought I've been having is to make sure the house could do without the A2A and do everything except actually put it in. But as above, I think the amount of benefits of A2A are fairly substantial, even if everything goes well and I could do without it theoretically. I'd love to have a price tag to the "A2A option" so during tendering I can forego it if I have to.

One further thing to point out, I wonder if people had opinions on: Rather than have a full hot water return - which, as I understand it, is really a loop of hot water circulating around 'your entire house' - the heating eng figures that 90% of my taps are local to the hot water cylinder, so instead he put a PIR sensor tied to a pump in the only remote ensuite to make sure that one starts pulling hot water the moment I enter that bathroom.. It does sound like a useful simplification of the design?

Fair shout. I think i'll just try for a buffer, as @joth pointed out a bunch of other smallish(?) reasons I think the small benefits are starting to add up whereas the downsides seem to be managable. I wonder if I can somehow have that buffer in my loft rather than try to crowd it in the under-stairs. Would it be a problem to have water go up 2 floors, then down again? Or would something more elegant be doable?

Mainly 'thinking ahead' to prevent it in the future, but.. My current rental house generates 3 types of annoying noise - anyone have suggestions on how to avoid this? 1/ The boiler - very recently replaced if that matters - apparently sometimes works on such a resonance frequency that it generates a very audible resonance upstairs in the master bedroom (yay.). 2/ Creaking when people walk. I'm sure it's all wood-on-wood (haven't bothered to lift the carpet). 3/ Expanding/compressing pipes I guess. Again when the heater's on, there's all types of 'tick tick tick tick' noises that I attribute to things heating up. Are any of these avoidable? Fixable? (for example I imagine I might have to put rubber spacers between boiler and the wall?)

Remind me - does your house already stand? Either way would love to see some designs if you're willing to share. You'd think! (below more) That is indeed similar in many ways It's an interesting point. The cost of installing (or at the very least provisioning for..) a secondary system is certainly non-zero. I guess I am expecting an extra-over of 30,000 when all is said and done, for the A2A. But doing it "now" is certainly cheaper than retrofitting, and on this forum and elsewhere I've heard many stories of overheating houses. Perhaps those were 'passivhaus teething problems' but I think part of these design choices are me making absolutely sure that particular situation won't happen. Am I right about that 30,000? the actual devices perhaps make a grand total of 10,000, so 20,000 to add the pipes, add the extra programming to the 'smart home'.

Interesting point. Yes I think it is the former (into void only). I will ask to clarify. Perhaps the FCUs are intended to run permanently but even with the heat/cool off that sounds less than ideal. Indeed, I'll inquire. The assumption is the ceiling void can be opened. But it will need to be designed to allow this of course. (and as.. I think you pointed out elsewhere) - I also need to make sure the downlilghters are designed around the FCU sections. will need some careful planning. My understanding is that yes there is rockwool, and we need to understand how much air it will let through, and work out those details. Thank you for your comments, these are all very worth figuring out today rather than later...

To be fair though, the network closet doesn't either. (nor the projector). But I take your point. Yes, not too expensive to oversize somewhat. I tried quite hard to find one of those devices but of the 4-pipe units that I could find, 90% were too big (20+ kW) and 10% were R410 only. Huh, I didn't realise ecodan does 'different things' for heating as it does for .. heating.. ? Yeah the guy mentioned defrost cycles. Yeah that's .. shocking really. I don't quite understand why? Did you ever find that out? The devices themselves are in the area of 1000 quid.. and while of course there are subtleties it's not that much more than bolting the thing to your ceiling or whatnot? I guess it sounds like the old adage in building: 'if you dont want to do it, charge an outrageous price'? It's a fair shout. Clearly we can't have both systems going in 'dumb mode' where they just turn on when temp below the setpoint (or for a2a, turn on cooling when temp above x). Short answer: no plan yet. Longer: I've spoken to a few installers that said they wanted to do it in KNX. I don't think I have the willpower to teach myself KNX or loxone beyond beginner level, but the idea is that this mech plan is really mostly a "draft for tendering" where I have 3 M&E teams who can ask a price for the pair, where I'd expect them to supply M, E and the programming of 'E'.

I think that's the point, yes. Producing heat at night is somewhat less efficient, which might not outweigh doing it on-demand? Ah fair. Yeah a buffer doesn't seem too expensive, the concern is mainly location..

Yeah I was wondering about this, but the guy said he accounted for it but I forget the detail. Let me ask. Well, on the other hand e.g. cooking on a powerful hob would also generate an additional heat for a longish time. But yeah I will ask. I think for A2W the ecodan 6.0 kwh is planned - PUZ-WM60VAA - very similar to yours I seem to recall? Yeah it's a bit of an exception to have the only thing that's needed in the house is slightly heating the UFH and nothing else.. eh.. dunno..I'll ask but the guy said that It isn’t wise to only run the heat pump overnight, it wouldn’t produce enough heat even if you could store it all. As you said, maybe electric UFH is a solution but eh, it's a bit iffy for various reasons, efficiency, reliability etc.

Yep, well insulated, and every window has either awnings (downstairs) or built-in blinds I've anonymised (please let me know if I failed, don't want to expose the unwilling) here: Heating: https://drive.google.com/drive/folders/1Fe7iriAq7vHQfj5WMB9FdpUKOJFZSO9O?usp=sharing Their comments: - Most houses in this country have around 24kW (or 24000W) heat loss, your house only has 3kW heat loss or 12% of an average house. As a rough idea at current prices you should be able to heat your house with an air source heat pump for less than £4 per day even in the worst winter weather. - Passive house criteria heating load is 10 W/m². Your house is 350m² with a total loss of 3200W which works out at 9.14 W/m² or better than Passive house standard. The EPC may not give you A+ because there are probably a few boxes you didn’t tick, but it is bound to be B+ because you are doing the most important things. SAP: https://drive.google.com/drive/folders/1lKLovkY0_JCoSo4P_6OJEZSbPDAtu1_U?usp=sharing - SAP rating: 100 A - Environmental rating: 100A - CO2 emissions: -0.31/year All in all, promising sounds, I seem to be hitting what I was hoping for, which is "near passivhaus" but not caring too much about hitting every checkbox just for its own sake. Would love to hear about anything that sticks out, for example if any of the materials can be replaced by anything more substantial. My main challenge is that I do have a few cold bridges that bug me, I was planning to post the final designs - I'm expecting them soon..

So - it has come to this. As I indicated a long time ago I wanted to be *sure* my house would not overheat, and I don't think I can safely do it with UFH (condensation) so at the end of the day, attached is my heating plan.. Would love to hear some feedback. There are a few things to note: - 2 ASHPs side to side in the garden, one multi-split A2A, one A2W. Both mitsubishi. - MVHR in loft, 5 FCUs that each can move about 2.5Kwh - UFH everywhere too (eh why not) - Solar is there but not indicated - 400L standard tank - gledhill heatpump lite (I was debating an OSO but the 40W less loss amounts to like 1p a day.. not worth my while. - Service shaft actually turns out not to be too used - Both my boxed projector, and boxed network rack have dedicated air lines. Tied into MVHR (heating guy says it will not be a problem to beam 400 resp 1000W (peak) worth of heating into the MVHR - No hot/cold buffers currently since these inverter-based devices can just run 'as much as needed' rather than alternating on/off but I could be persuaded Looking fwd to hearing any further thoughts Full plan - all floors, drainage etc here: (sigh, can't upload more pics) https://drive.google.com/file/d/18N3Pk5uOxdq9G9GJAT6txxETgGfLQw5I/view?usp=sharing