Iceverge

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.