ProDave

A "why has this suddenly gone wrong" question is much easier to answer if you ask the question "what work was done in the house immediately before it went wrong" And you have your answer. Who fitted the sockets? I would be VERY worried in their competence if they mistook a thermostat cable for a ring main cable, so it is more likely they disturbed the thermostat cable either pulling it out of it's connections inside the thermostat, or they drilled a hole through it? If you trust their competence now, get them back to sort it out. for free of course.

I will be interested how they implement this at flats and inner city builds with no off road parking.

It is hard to buy land that is not for sale. But I managed it. the plot we nowhave a house on was empty for years. I by chance met the owner, and asked if he wanted to sell it and the answer was no. Over the years I asked several times and the answer was still no. Then I had resigned myself to buying a plot that was for sale but not in as nice position and further away, so out of courtesy I phoned him one more time and told him of my intention to buy this other plot. His reply was "give me 24 hours" and he phone back next day to say I could buy it.

Yes, my idea is aimed at how to mix the very hot water from surplus PV heating around a bit. What I find, is when I get this temperature step thing and the ASHP comes on because the bottom of the tank is cold but the top is still piping hot, is the ASHP does not run for very long, less time than you might expect. I am convinced that once it starts heating, this sets up convection currents within the tank that draws the top hot layer down and helps with the mixing process. Just speculation.

I was surprised just how little I wasted. ALL the offcuts were staked up in size order in an empty room, and when i needed less than a whole sheet, my first place to look was which offcuts can I use up first before starting a fresh sheet. Some offcuts remained on site for many many weeks before getting used.

What I am talking about is something to stir up the water in the tank so instead of having 70 degrees in the top half and say 30 degrees in the bottom half, it mixes it around a bit when it senses a large stratification like that and ends up all at say a nice even 50 degrees. Thermostatic mixers ensure nobody notices a change in water temperature. To make an accurate "fuel gauge" for an UVC you would need several thermometers all the way up the tank, hence if I were ordering again, I would have got at least say 5 thermostat pockets evenly spaced up the tank.

that basically means your PV generates more power than the house uses each year.

Thanks for that. That looks possible. I will be interested in the cost. Remember that word I mentioned, Compromise? the compromise here is thinner insulation in that bit of timber frame and ditching the insulated plasterboard.

We only have one such joint where the door to the bedroom balcony joins to the bedroom window. This was fitted by our builders. I believe there was some form of flat joining strip supplied, it was very thin and not visible when completed. Lots of sealant was applied before offering the 2 halves together, and the builders hid the fixing screws by removing parts of the door frame that the locks latched into, drilling and fixing through behind those, and then re fitting them, so all fixings at the joint are completely hidden. No daylight visible, no draughts ever noticed, even when the house was depressurised for the air tighness test.

The problem is not much better with a conventional unvented hot water cylinder. The ASHP uses the lower of the 2 thermostat pockets to measure the tank temperature. Near the end of a sunny day like today it is reading69 degrees. All that lovely heat courtesy of a bit of sun, some chemistry and some electronics. BUT from watching what happens next, there is "room for improvement" Someone takes a long shower (far longer than necessary, but they blame the duration on the amount of products needed to be applied to their long hair, a problem I do NOT have). The water at the top of the tank is still coming out piping hot, but what has happened is the hot water in the tank has all just "moved up a bit" and at the bottom replaced by cold. As soon as the hot / cold transition gets above that lower thermostat pocket, the ASHP thinks the tank is cold and fires up, and I am there shouting at it saying why the b****y hell do you want to come on? If I were designing this system again, I would specify a whole row of thermostat pockets up the tank, and I would specify an extra tank tapping near the bottom of the tank, not far above the cold inlet tapping, and I would have a circulating pump that could come on to stir up the hot water in the tank to even it;s temperature out a bit, and hopefully avoid the ASHP coming on when not really needed. but I can't see a way to retro fit that with no tank tapping low down to circulate the water to.

Well done. Much the same for us, our air tightness was 1.4 though we could find no particular leak. I was disappointed but the tester was nearly wetting himself with excitement at how good it was. We achieved an A94 so you beat us. But it is a smug feeling having an EPC A and no improvements suggested. In spite of SAP supposed to be accurate, it still managed to estimate out heating load as way more than practice actually says, and in fact in that respect Jeremy's simple heat loss spreadsheet was more accurate. Our EPC A is printed and on the wall next to the consumer unit. I think our BC inspector at completion remarked it was the first EPC A he had seen.

If the frametherm goes right to the apex I don't see an issue. Put any cables in e.g. for lights before you close it all up.

Cut the PIR edges at an angle to match the roof pitch and there will be no gap?

I think the example in the photo works, because it is just 2 doors, and one slides each way, meaning just one door sliding into a pocket. There is it much easier for that one door to seal to the pocket both open and shut. I also note in that picture the bottom storey of that wall gets thicker than the upper storey, presumably to give a wider cavity for the pocket. If you could compromise and have your door as just two, that would be a better way to think of it, but your right hand section of solid wall would need to be wider to accommodate a pane sliding in there (effectively meaning you doors would be narrower), and one very long steel to span that larger opening width.

If you are going to pursue this, there is one word you need to understand. COMPROMISE. If you slide all 3 panes into a pocket on one side, that will take up a lot of the width of the frame of the house. Much of that width would normally be filled with insulation. By leaving a gap there (that is what you are doing, leaving a great big open gap in the wall occasionally filled with the doors) you compromise on the amount of insulation so that part of the wall will be cold. You might look at making that section of wall thicker to get that insulation thickness back? But the big one for me is air tightness. If as in your example photo just one pane slides into a pocket, then you might be able to design the window frame so it makes a reasonably air tight seal whether that pane is slid into the pocket or slid into normal closed position. But you want all 3 to slide into the pocket. Just how do you think you are going to get anything like an air tight seal around a hole in the wall 3 panes wide, when they are all shut, and only 1 pane is filling that hole? Find a real world example of 3 panes sliding into the same side and come back and show us how they did it.

That would be putting the heater outside under a rain canopy.

They are in Scotland for 5 days I think. Why was the system drained down? What did the pre sales enquiries say about the state of the heating system?

I would say get those waders on. Be careful you don't end up with those bogged down in the mud, sticky "seabed" mud is lethal stuff (literally in some cases) Or work from a boat?

I am now exporting about 2kWh per week. That is mostly mid day when if nothing else is running in the house, the PV generates more than my immersion can absorb (it's actual power appears to be 2.8kW) and it's too hot in the house to dump any to the 700W convection heater. I do say out of spite I will just move that dump heater out to the garage.

I much prefer ground floor option 1. Option 2 seems a bit disjointed and does not flow as well. If you want more direct access from the side create a corridor from main hall to side door through what is currently plant room.

But at the times when the sun is shining and you are using surplus PV, there won't normally be any lights on (except in a basement perhaps?)

No it will be more like 700W

I will watch this with interest as we too have a "balcony pending" but ours probably won't be done this year. This years money is being saved up to get the driveway finished and surfaced properly. The difference in design, is ours, the support pillars (there will only be 2) will be at the mid point of the balcony, not the outer edge, so almost all the weight will be on the pillars and the attachment to the house wall is just to stop it falling over. And we hope to use glass ballustrades.

It's a bit like watches. Ask a man with one watch what the time is, and he is sure. a man who has several watches is never quite sure. If you measure a gap with one measure, then mark the bit of wood with the same measure, all will be fine. Work out which one is missing a bit and throw it in the bin.

you mean the other half filled with everything to had to move to make this half look tidy? Looks very good.