SteamyTea

Get a proper heat loss calculation done? Are you in Cornwall as you mention Kensa.

Starting with your DHW, if you have a ΔT of 20K i.e. heat from 30°C to 50°C, that will be 5.8 kWh, call it 6 kWh. If you use that amount every day, with no reheating, then that will be ~2.2 MWh/year, you have around double that figure, which seems reasonable. Your 10 kW at -2°C is about right for the MCS minimum temperature (supply 99% of the time). See chart. You can work out your heat loads from the minimum temperatures and how long they are likely to last.

It may have to in the future, these houses often get battered by the sea.

I am surprised that you have never modelled it. Plotting thermal conductivity against thickness produces an exponential decay, similar to Newtons Law of Cooling i.e. rapid decline at first, followed by slow decline as the thickness increases. The line stays the same shape, regardless of temperature differences, just that the power losses change in proportion. So taking the two extremes of Styrofoam (0.033 W.m-1.K-1) and concrete (0.92 W.m-1.K-1), you can see on the chart that even adding 0.01m (10mm) of styrofoam, will always outperform concrete. So the best value, for poorly insulated buildings is to add insulation. It is only when losses though air leakages are greater than conduction losses that the algorithm has to be changed. The trouble with solving air leakage is that many 'holes' will be in places that are hard to get at i.e. under floors, and if airtightness is significantly improved, then mechanical ventilation must be used to control humidity.

Do a couple more and it will become very easy to do, once.

It is why they say turning down your heating can save 20% on your energy bill. It is, in part, to do with incidental gains i.e. passive solar, cooking, bathing etc. It is also, in part, to do with external temperature variations, which follow, quite closely, a normal distribution curve.

Probably the same people that bleat the loudest about green taxes, energy companies ripping them off, and have never read their meters.

Not really the way to look at it. The idea is that energy usage is reduced, preferably to a level where domestic PV, a long with HP technology can balance each other. It is not to do with the actual cost, complexity or return on the insulation required.

There are roof integrated PV mounting systems that can also take Velux windows. Do a bit of research, i.e GSE system, and see how the module and tray sizes fit in with your design.

So does using descriptions like suitcases, for heat exchangers, and relating a heating system to holding a camera on a film set. If you want to be taken seriously, learn how the system works and take advice when it is offered, it has to be better than shooting the messenger.

Women and walnut trees eh

Poor (expletive deleted)er having to deal with this.

Pick another fluid. https://www.engineeringtoolbox.com/fuels-densities-specific-volumes-d_166.html

By pointing out it has been done before. And there is an assumption that most people look the other way.

Just imagine paying a man to fit, before FiT, some panels to your nice south facing roof, then having an Architect move in next door. An Architect that wants to win an award, wins it, then moves out.

Yep. It is hard for people to understand why a small shadow can make such a large difference.

Have you used a manometer? Then worked out the pressures.

What does this mean? If you have chimneys, dormers and other odd things getting in the way, PV may not be worth it.

Yes, and it can quickly highlight a problem, like when my fridge went permanently on. I saw the rise in usage and got a new fridge within days. Was also useful when the element in the water cylinder went, could see that it was only partially drawing power as it failed. I use basic storage heaters and a 200lt water cylinder. I just control the times with secondary timers. I did muck about with removing elements from the large storage heater (21 kWh), but decided that using just timers (cheap from eBay and have lasted years) was easiest, and can get them to fit in with times of low emission generation.

Let us know how you get on with them, I made my own.

Do you have an electrical energy logger?

Mine are similar. I have disabled the late evening times as I only need about 3 hours. That way it heats the water later, or closer to when I need it. As long as I use it after the shut off time, I reduce the standing losses.

I am with EDF and never got offered 5p for night rate, not even 20 years ago.

Which is near enough 5.1 kg/m2

Not if you use a large tap.