Iceverge

Single A2A and direct 300l UVC here and pull cord heaters in the bathrooms. Pros. Very simple to control. Daikin app for a2A and time clock for UVC. Spacing heat is cheap. Cheap to install. Heating the UVC to 70/75 on immersion allows it all to be done on TOU tarriff. Simple to repair. Cons. A2A sounds like a fan. I can't fix or install the A2A, needs an f-gas man.. DHW uses 10kWh/day. Vulnerable to elec tarriffs. It works just fine, add a few PV panels and I reckon it's the cheapest thing you could have over a lifetime. Next time I think a monoblock A2W, cheaply bought. A 300l UVC. Simple UFH. Under tile electric mats in the bathrooms. It'd be as cheap to run but be more luxurious than the blown air option I have. Allow a 70mm blanked duct through the wall and a fuses spur for an A2A for cooling if ever needed. Ps. I'll take suggestions of "simple" UFH. Could a single 100m loop be enough. I don't know enough about these things

That's fair.

Go the whole hog in that case. Take the insulation and airtightness line outside the attic space and a regulation staircase to access. Design dependant though it can be much much dearer. In our case making the footprint bigger or a garden shed was multiples of times cheaper. Suitcases in the garden shed or be sensible and just take hand luggage. MVHR should be inside the heated envelope, I've seen issues with vibration and noise when in the attic. Care is needed. Also you need to get at them to replace bearings and filters. House battery should be away from the house entirely in my view given the severity of Li cell thermal runaway. Kids toys should be sold on eBay unless they're being used. I'd have loved a trainset as a lad but couldn't get any cheap as they were all hoarded in some geezers attic......

I was dead set against it from an air tightness and hoarding point of view. I have never seen anything in an attic that didn't belong in a skip. I even found a timber box of gelignite explosive in my parents one from the 1950's. It's a place where people who can't organize their brains stick their crap. Rant over, I did include one, only for access to inspect. I might visit once a year to check the roof and to say hello to my insulation. Airtight(ish) + insulated(ish) attic hatch and 500mm OSB upstand to keep the cellulose in situ. I added 500mm of a PIR "plug" that fits into the OSB upstand box to keep in the heat. I reckon it comes with a U value of 0.05W/m²K. No storage allowed thank you very much.

Seriously though. Could some flat steel plate be sistered to the joists to add strength. Painted black noone would notice.

Paint the underside of ply with the underside of your favourite BBC radio4 personality . Far more of a talking point.

I think @Gus Potter mentioned before where he put ply above and below a floor to make a it stronger. Do you have enough head height to make this happen?

An interesting project and I'm sure I'm not alone on wanting to see more of it at some stage. Agri barns are good for their job. Providing economical shelter for agricultural goods, livestock fodder machinery. However making one into a house is monetary madness. It's often cheaper to knock and rebuild a new barn for farming rather than repair an old one not to mind making it habitable. The rules on this are idiotic.

What are you building, I'm invested now?! This lovely builder will horrify you. Framing with fresh sawn green lumber! https://riversonghousewright.wordpress.com/about/25-riversong-truss-system-home/ Can you not just get a pallet of timber delivered wrapped like these ones here?

I'd would prefer nothing there than that layer of poly. It will be far too resistant to vapour to allow any drying back into the room and your roof rafters will get damp. Intello or some other low sd or variable sd membrane or nothing What's being constructed is a recipe for rotting your timbers.

Most of them will grind out if say, there'll be little big aggregate in the humps anyway so it might be straightforward enough.

No but they do let me suck on the beer mats for free. Is there any reason we don't use air heating and cooling? Surely it's an ideal fit for situations where active cooling is required. Laying an A2W on top of an A2A system seems like unnecessary duplication. A stand alone ESHP for DHW would eliminate compromising heating the house from heating your bath and visa versa too.

Passive class house here. I made every decision based on cost as I'm so tight I lick the drips out of the milk carton. No central heating to begin with. House too cold, 17-18deg. Nicked this from my parents shed and plugged it in (anywhere downstairs was fine) . It broke after 2 years so I went to the dump and pulled another one from the scrap electrical pile. (True story) Then electric prices doubled so I put an A2A unit in the downstairs hallway. It squirts enough calories into the house to keep it all toasty. Haven't tried cooling yet as that would unnecessarily disturb the spiders in my wallet. Bathroom was a bit chilly on my man boobs so I put in one of these in one bathroom. It cost €30. The kids had to make do without sawdust on their gruel for a month. It hit the spot but the tips of my ears were hotter than the tips of my toes and that pisses me off. So then I bought one of these for the downstairs communal bathhouse. €60, Christmas has been cancelled until 2030. It fluffs up my curlys excellently and delivers a beautiful Saharan breeze to my eyeballs. Better than the 2 bar fire above. Best of all I made sure to hang it on a stud wall so it makes a racket and you never forget to turn it off. Total capital ofheating........... ~€1600....... Annual heating usage 2025 for 186m². That is excluding the twiddly bits (~30kWh) for warming my titty bits in the shower. Like @TerryE says do da numbers y'all..🇺🇸

Swap straight out for bathroom extractor fans.

Wall mount. Or make a raised floor for the MVHR oN rubber feet or springs or hang from the rafters. Otherwise the vibrations on the joists will annoy you. No, exhaust condensation is taken care of by a drain under the heat exchanger inside the unit. Long term maybe better. You could put MVHR cowls where made most sense for the system then .. Add another roof hatch somewhere else? A cheap one that you can just tape up to air seal once the unit is in place. Otherwise there's slimmer MVHR units available. Flexi pipework is woefully compromised. Stick to rigid if you can. One thing to consider is how your house will behave in a fire. If you have a fire now in a room with a fireplace is it possible that it could travel to the attic?

Jebus .... Recirculating loop on a PIR I imagine is the way to go.

55m!? Is that a typo?

Could do the sums on it....... 150l of DHW water heaters to say 50 deg is about 7kWh. 30m of 22mm looped pipe and a room temp of 20deg and a water temp of 50deg is a heat loss of 250w. Say you run it 24hrs a day and you get 6kWh. Put it on a timer or a PIR sensor and you'd probably half it. Of course you might have less flushes in the first place. Your mileage will vary. I reckon it's still nothing compared to running a 10mm pipe run radially from the UVC. Will do sums later ...

My fear is that a gale would send those tiles to the next parish but I suppose it's not as windy where you are. A vent in the fire would be a good start. Others any rain or damp that finds its way in will never dry out.

I was being frivolous. Suggesting it might be less hassle to just use more energy to stop the ASHP cycling like Tadje Pogaçar on Alpe d'Huez rather than chucking it entirely.

I meant in the winter........ Save the heat pump having to cycle...

You could just have put the MVHR on summer bypass!

If you're set on crimp fittings and mlcp I'd run 12mm to everything hot except showers and baths and maybe the kitchen tap in a radial fashion. Colds can be Teed off within a room and 16mm. You shouldn't need 20mm pipes unless you have a gravity system. A hot fill for the cistern could easily dump 150l per day of DHW down the bowl for a family. It's be less wasteful to just run the tap while you used the toilet until its hot. However....just use Hep2O. Don't insulate anything apart from the hot at the cylinder, it's a waste of time. I have a thread about my woes somewhere.

Why the change from your 6kW unit?

EPS can soak water but that's typically only when fully immersed and then worst case is only 5% or so. The amount wicked up by capillary action from damp ground is typically negligible as the capillary network between the EPS beads is far larger than brick or soil. If you're concerned, a capillary break like a shovel of gravel below the EPS would certainly solve it. On the other hand if you have some XPS to hand that would work equally well in this situation if it has sufficient compressive strength.