SBMS

It seems Aerobarrier themselves recommend doing after plasterboarding. I guess if the system is designed to find air paths under pressure you want the physical model to be as close to the finished one as possible. Doing dot And dab would create a service cavity that changes the airflow And would potentially create leakage paths which weren’t present pre PB??

Okay fair enough (and you’re right my cracks comment was a bit stupid!)…. But if it does all that does it matter if the plasterboard is in place or not? Still Can’t see the benefit of doing it after boarding rather than before if all first fix is done?

Understand that first fix needs to be done (but this behind the PB typically).. but if we PB first then AB that puts the AT layer at the PB layer. If there are any cracks etc in plasterboard later then that’s a path that AB will miss? But if the AT layer is behind PB then boarding (with full perimeter dabs) can only increase airtightness? Or am I missing something

So AB after dot and dab? Would have thought having AB at the block layer would be best so pre PB?

Indeed! Think I might have a go myself with soudatight and see where I get?? Any other aerobarriers out there? What did you do pre aerobarrier

Not yet but am not sure what it would tell me. I’ve seen case studies that get airtightness from 6 to 1.0 so if I blew 6 today would that mean I should still crack on with aerobarrier? I worry that aerobarrier gets you a great result on the day but does it persist long term? I know they’ve tested longevity of the material itself but presumably this is fairly controlled. Does it cope with movements around junctions well for example 🤔

Am considering aerobarrier… so far we haven’t done any airtightness detailing for - window junctions/across cavity - slab floor to wall junctiob - liquid membrane/parging of internal block work (traditional masonry, 200mm cavity with eco beads) I have implemented a Tony tray and done airtight board in room in roof with taping.. Does aerobarrier negate the above entirely? Or should I do it (was thinking of using soudatight and parging with it as well). do I need to? I know that aerobarrier gets good results for air blower but does that hold up over time? Eg does it deal with the movement at window joints that tape/liquid membrane does? And if I go around with liquid membrane do I then need to shell out £5k on aerobarrier? I wonder if it’s diminishing returns - the difference in heat loss between a 1.0 blower test result and 2.0 For example is about 150W!

I wonder if anyone on here has ever managed to find the minimum heating capacity/modulation figures for the Aquarea M Series range? I've tried searching the whole of the Panasonic Pro Club and can't find any technical information? Part of the reason I wonder is because the 12kW and 16kW are exactly the same dimension. I remember that two of the larger vaillant arotherm models were actually the same hardware, with the output software limited... so I wonder whether panasonic does something similar but have a similar modulation floor?

Thanks everyone for your input. Have already got swim spa sorted and appreciate the advice John but the spa comes with a pump included and don’t want to confuse the spa installer and the heat engineers so will keep them separate! I think I’m going to go for the 12kW but I have also asked Panasonic to do a full heat loss calculation as well so interested to see what they come back with. Both mine and heatpunk predict 9-10kW so I think a 12kW will work. It’s £1500 less for the heat pump as well - not to be sniffed at. I did hesitate momentarily because I wondered if the cooling load could end up above this… but I’ve had a very lengthy thread elsewhere with @JohnMo where he said my predicted level of cooling was mad so 12kW cooling through fan coils should also be enough for the hot days…

Thanks John. I did account yes, it’s got An insulated cover 95% of The time but also the room it’s in will Be a bit warmer as well. it sounds like you would err on the 12kW side. One frustration is Panasonic don’t seem To publish their modulation figures for these machines so I don’t know what they would typically modulate down to. If they both modulated to a similar level I probably wouldn’t be as concerned. My upfront cost is a bit more for the bigger machine granted and if I didn’t use the extra kW it wouldn’t matter… but if for some reason I’ve undersized it I’m a bit stuck. Sound logic? the installer says they haven’t come across a build that’s averaging 19w/sqm before and think they’re nervous we will be cold. They’ve used higher air change figures in their calcs I think as well (as per mcs).

no - the spa has its own heat pump. It’s basically a big hot tub so a closed system driven from its own a2w pump. We are going to put some insulated plasterboard to reduce bridging of the steel lintel…

Going to answer my own question here.. I guess my heat losses is worst case rare day not the average…. has anyone else ended up oversizing? Or tracked whether their heat pump was oversized?

Is it not likely my heat losses are bigger than calculated not smaller? As they don’t account for inaccuracies in installation, thermal bridging etc?

Hope I’m going to use all of it! I’m the idiot putting an 8x3 in ground swim spa in so that’s a fair chunk of the floorspace as well

I’ve done my own heat loss calculations for our new build. Verrrrry roughly the spec of the house triple glazed windows 0.76 average 200mm cavity with eps beads at 0.15 Doors averaging around 1.0 Floor averaging around 0.1 roof has 304mm blown cellulose 0.12 going for high level air tightness mvhr the build is big - gross floorspace over 3 floors is circa 490sqm. We are going Panasonic aquarea. Wall mounted fan coil cassettes upstairs, UFH on ground floor. We have selected the Panasonic m series tcap because it natively supports dual zone (useful for cooling) Crunch time - I need to now select the heat pump. My calculations are coming out around 9kW. Heat punk is around 9.5kW. MCS installer is coming in more conservative around 12.1kW. I suspect we are somewhere between 9.5kW and 12 but we do have some unfortunate thermal bridges such as a big piece of steel over 8m of sliding doors. These thermal losses aren’t accounted for in my calcs. my dilemma - do i go for the 12kW model and hope its enough or jump up to the 16kW model?

Same here. Made a formal complaint (it’s not lawful for them to keep the money if no closure occurred I found out during the process). Received a full refund.

Easy: build yourself using ChatGPT. easier: use jeremy spreadsheet. easiest: https://heatpunk.co.uk check each. They were all within a few percentage of each other (which is good enough for heat pump sizing to size to nearest pump).

No. But there are wall units that are basically the same as the a2a units they just run chilled/warm water as opposed to refrigerant. https://www.aircon.panasonic.eu/GB_en/product/aquarea-air-smart-fan-coil-wallmounted/

We are Doing this but driven by the heat pump instead of a separate air con. for reference - the cost difference to install fan coil units upstairs (7 units) with fully lagged pipe work (allowing us to run the fan coils at 9degrees when cooling) is around £7k (over first and second floors). This is only a bit more than quoted price for UFH for those floors. This is much less than price of air con and means our heat pump isn’t sitting idle for half the year. Fan coils are also pretty efficient at running at low temps as well. I hope the strategy works, but in theory it makes sense??

Thanks. We’ve got 254mm joists and would only put 100mm pir in between but still fiddly not as good as all on top etc…

Agreed. Their analysis looks sound - and they don’t account for mvhr which probably helps even more. Even still.. I feel a niggle…

Why?

In two minds… about to start on our flat roof. Originally had planned for 200mm PIR as a warm roof. Due to a number of design issues we are looking at reducing this down and potentially looking at a hybrid roof. have had an interstitial analysis done by Unilin. By their reckoning if we put 100mm between joists and 140mm on top that yields no risk of condensation.. My thinking is whilst aesthetically we can reduce the parapet wall by a course (60mm) to improve aesthetics… is it worth it for the ‘risk’ perceived with a hybrid roof? Anyone else done this?

Probably not answering your question but I spent ages going round in circles on this and decided to go wall mounted fan coils upstairs. Panasonic aquarea system. Means we can do heating and cooling. 2 Temperature zones (natively supported by the system) so can run UFH and fan coils at different temps (low if needed for cooling). I’m not sure the cost of UFH upstairs is justifiable but I do think the cost of proper cooling (AC level cooling) is justified - the way our summers are going. Got Panasonic coming out in a couple of weeks to provide a technical assist on the system design if you had any questions

Am using UFH - why is this not ideal? Sorry I am not the OP re the large garage/ pool. Mine is a 10mx6m pool hall with a ln 8x3m in ground swim spa in it.