SteamyTea

Yes. It was just a guess, no idea what it really is, though a few people on here have data from their MVHRs that could work out a seasonal average. It is part load that can be a killer to efficiency, not so much of a problem with DHW heating though.

Negative exergy maybe.

Did it cause and extra noise in the MVHR vents. I have wondered about one of them for my place (50m2), but was thinking it was probably oversized. Though down here a bit of extra ventilation is not such a problem as the mean winter OAT is pretty high.

Your old place was quite large I seem to remember, is that right? I like the idea of energy scavenging, but it is just that, a scavenge, and a rule of diminishing returns. Also, to get the right efficiency gains reported, one must use the absolute temperature scale, not the celsius one.

You can get Exhaust Air Heat Pumps to for hot water. @Gone West had one I think. Down to the more fundamental point though, it is down to the amount of air you have to shift. 0.85 m3 of air weights a kilogram (ish) and has a specific heat capacity of 1 kJ.kg-1.K-1 (ish). That is 0.00027778 kWh.kg-1.K-1. So say you need 3 kWh of hot water and there was a 1K ΔT. 3 [kWh] / 0.00027778 [ kWh.kg-1.K-1] = 10,800 kg Even of there was a 5 ΔT then that is still 2,160 kg, 2.2 tonnes of air to shift out your building, via the MVHR and into a heat exchanger on the ASHP. If that was done at a constant rate, day and night, it is 92 kg.h-1 and could be a lot higher in reality if you need a more domestic hot water or a faster heat up time. Would work in a larger volume house, but not so great for a smaller place.

Polypropylene lined. Get a great finish at a low cost. (I used to make concrete moulds, Reigate junction on M25 was one of mine and a flood defence in Swansea)

You raise the marketing budget and I will be the technical director.

Easy enough to make your own mould up and cast yourself.

I have often wondered why a clip together, melamine faced plywood/MDF/other substrate is not used. They work well in shower rooms, can be fireproof, and relatively easy to DIY. And you can screw into them without a Rawl plug.

My electric supplier (EDF) uses UTC (GMT in old money). Have you checked for that?

Right. Then should be OK. Will loose about a watt per degree temperature difference, and as you say, will stay mostly in the building. The MVHR will suck it away and redistributed it.

Is that missing a 0. Rethink radiators.

I seem to remember that when I did my Part P, to get legal cover I would have had to join a trade association and pay a fee. Think it is similar with gas. So we already have two systems that work reasonably well already, I am sure something similar could be set up for low temperature domestic heating systems. Would not stop all the cowboys, they just do whatever suits them, and then vanish, but some 'quality of service', policed through Trading Standards is needed.

Where the median age is 17, compared to the world median of 30. Or are you thinking about the hounds living in kennels.

Wales has Penrhys. An architectural and building marvel.

Welcome I act neither my age or my shoe size.

Hard to tell from the pictures, but you may be right about the drainage. It also looks like someone skimped on the materials. It could be a mismatch of resin types, but that is an unknown now. But most likely, as @joe90 says, it was initially laid up onto something that was damp. You could try recoating it, once cleaned up, with one of the polyurethane systems. They have good reports. @Onoff did his roof with it and it seems to have worked.

You are.

Or in parallel but with polarity reversed.

Yes, was all peaceful and very civilised today. The shit happens come the next bank holiday, then the relentless months till November.

Not today, he was in our restaurant and hour ago.

Every couple of week I pass International Plywood near Gloucester (I am on the M5). I often wonder if they are as good as International Rescue (a 60's puppet show).

The crack may well stay the same. Trouble is that water can get through the crack, then onto the GRP substrate. Normal polyester resin, when consolidated with glass fibres is not intrinsically water proof. So once water gets between the acrylic shell and the GRP, failure has started. A similar problem happens on boats, they call it osmosis, though this is not really the correct term.

I am guessing this is an acrylic vacuum formed shell, then reinforced with GRP. Replace it. See if it is covered by your house insurance.

When I was a kid I found some of those green brazing goggles. Popped them on and was quite fascinated in how they made everything green. Guy stopped in his car and said 'hey, just think how great everything would look whizzing along in my car' I said 'I only found these, I am not really a (expletive deleted)ing nonce welder'