SteamyTea

You can get a water cylinder with a heat pump built in, that may be the cheapest to run, though the most expensive to buy (the Ecocent is just a branded Chinesium model at 4 times the price). While an E7 DHW system is cheap to run and install, it does mean that your daytime electricity is expensive, that will negate much of the savings if the A2A heating. Instantaneous water heaters are good, but need to be high power i.e. 10 kW or more. This may mean updating the consumer unit. You may need a water softener as well. So really just a case of booting up Excel and working it all out.

May be micro inverters on the back of the modules.

You can get PV diverters. These units are designed to turn on a remote load i.e. water heater, when they sense power being exported. There is usually a minimum generation they can work down to, so good for resistance loads, not so good for inductive loads like a heat pump. Heat pumps don't like being started and stopped too often. The usual way to 'run' a heat pump from PV is ti take the statistical route i.e. max generation is around local noon, so a couple of hours either side. You will still be importing energy during these times, but less than usual. You have to balance that with whatever you get changed for you importing energy, it may still work out cheaper to run the heavy loads at night, only you know your tarrif. Depending on what you get paid to export, you may find that the cash generated is a better option.

Or a water pipe with clear ends.

Can you run a Mac OS on it?

Did I get it the wrong way around, they are fixed current devices (I think LEDs are the same).

I am not sure about this (as not an electrical engineer) but I think that PV modules are fixed voltage, it is the current that varies with solar intensity. If that is the case, then as long as the module voltages match, there should not be a problem. If that is not right, then maybe individual module optimisers can overcome the mismatch.

3 metres

Feel free to improve the code and post it up.

"The build starts with lovely weather but by the Thursday most of the UK has a yellow weather warning for rain, we had 23mm of rain Thursday, 14.2mm on Friday and another 27.7mm on Sunday." When I moved into my current place in 2005, it rained every day for 66 days. Plan for constant rain.

Be interesting to start a thread on here about getting data out of heat pumps. There are enough people, with different heat pumps, and a few people with good IT skills, should be possible to create a few basic packages that run on basic 'computers' and can store data. Leave the analysis up to the people that are interested, just create some text files of say electrical usage, run times (with timestamps) mass flow rate, flow and return temperatures, room temperature and outside air temperature.

These seem to give mixed results, especially with the electrical input numbers, which are critical.

With a raspberry pi. Some cheap 1wire temp sensors, a flow meter and something to read the electoral power input (see my blog).

Look for any sources of liquid water. These could be water pipes, gutters, down pipes, ground level above a damp proof course. Condensation is generally caused by a cold internal wall, so may be low levels of insulation, or very high humidity, as in a bathroom.

Have you thought of making your own?

@Colink Will be here be enough room to fit pipes, and insulated them in a false cavity? Many people think that it is not worth insulting pipework unless it is also used as cooling. I disagree with that (not the cooling) as you just end up overheating an area with lower thermal resistance to outside. The whole idea of the vapour control layer is to stop warm, moist air condensing in a cold cavity. If you do get to 0 ACH, then you have a nice problem to deal with, just fit mechanical ventilation and heat recovery. Your son really will wish that he removes all the old plasterboard, increases the stud depth, fit his news central heating pipes (properly insulated, a well taped VCL and new plasterboard (possibly in resilience bars). I is very little extra work and will be a lot easier for a much better job.

Thanks, just leave out the odd indices, then it becomes a lot shorter

Integration, in mathematics, is continuous addition. So I suspect that it works in a similar way as a heating controller. It keeps adding, or subtracting, until the desired outcome is reached. The outcome will be one of at least 3 bounds, the other two will be minimum and maximum output if the unit. The unit controller will probably have an initial set point (in the middle of the performance curve) and then is manually set to add, or subtract 'degree minutes'. Degree minutes are the product of the temperature and the time it is delivered i.e. multiply flow temperature by how long the system is delivering (it may be the difference between flow and return as that is the energy delivered). The same can be achieved by simply switching the system on and off for varying amounts of time, but that is inefficient with a heat pump (but works well with a resistance heater).

I don't think so as there is only a tiny amount of hydrogen produced. If aluminium and concrete produced lots of hydrogen, the worlds energy crisis would be over. I would think that the biggest problem is liquid water, it is not called the universal solvent for nothing. This will, in time, break down near enough all materials, with polyurethanes being one of the faster ones. I don't think this is a problem for housing though.

The wiring goes in 'safe zones' so check with an electrician. Plumbers tend to put pipes all over the place, so check with a plumber, though you will probably only need standard 15mm. Don't confuse the lower flow temperature with lower output, it is more complicated than that. As for insulation, basically the same build-up, but thicker. No need to use a foil backed, or insulated plasterboard, the VCL does that. A VCL (it is usually a sheet of polythene that is taped to make an airtight 'bag') is to stop moist air migrating to a colder area and condensing, it is not for improving wind tightness. Wind and airtightness need to be dealt with separately and go on the cold side. They are vapour 'open' to allow moisture to evaporate away to the outside. Basically the warm side i.e inside, is the most vapour proof, then as you go towards the cold side i.e. outside, you allow more vapour open materials. This allows any moisture to evaporate to atmosphere and not cause condensation related problems.

Don't listen to that tosser, he just likes spouting off.

Assuming that internal space will not be compromised, just remove all the stuff, existing plasterboard, VCL and insulation. Make the sheathing as airtight as possible i.e. perfect. Then increase stud depth, reinsulate, VCL and all plumbing and wiring that needs changing. Sometimes it is just easier and cheaper to start again.

I have never measured a sheet of foam insulation across the diagonal, how accurately are they cut. Most 'foams' will shrink over time.

If the roof is sloping towards the south, have you considered solar, either PV, ST or both? PV is the easy and cheap one and could part charge, and sometimes fully charge a 100 lt DHW cylinder. But as you already have a 10mm cable, you can run a 45A load with very little losses ~1V. My DHW is a simple gravity fed, 210 lt, Economy 7 cylinder with a 3 kW heater in it. I pump both the cold and hot and have a good shower.

Not really, because as you rightly point out, our infrastructure is now out of date. Eventually there has to be some individual responsibility to help out the rest of society. It is why we have laws. If you take an easy, but poor argument, using a motoring analogy, I have never had an accident when travelling over 90 MPH, so why can I not always drive over 90? Even if I do have a catastrophic accident at high speed, the sum of the energies would still, probably, be less than all the lower speed accidents I have had. So on balance I would do less overall damage.