SteamyTea

Welcome. As Gus says, do a basic heat loss analysis, and if you know how much coal you have been using, and when, the amount of energy that supplies can be estimated. I would be very surprised if Octopus actually supply 100% renewable energy, I don't think they have the generation capacity, more a case of trading with REGOs and double counting their generation capacity. They have a habit of buying existing generation capacity or partnering with other companies (Tesla being one of them, which boosted their share value). I am starting to think they are not very moral.

Have you read the work of John Richard Gott III. He claims to know when things will end. Gotts_Doomsday_Argument.pdf

Now I am home can show you mine. Going into bedroom now as been away 10 days. House is at 16⁰C, so not too cold.

That is my whole point, it is not the materials, per sec, it is the techniques that out them all together. Within 2 miles of home, need milk.

This 'letting buildings breath', where is the moisture coming from? A brick, or block, or even a bit of stone laid in the same fashion as sometime in the past, will have the same problems. As far as I can see, it don't matter what sort of concrete, render or mortar us used, if the damp us getting into the structure, stop the damp. Usually good, controlled, ventilation is all that is needed. Re the windows. My windows are old (34 years), I just changed the glass to ones that had 16mm gap instead of 4mm gaps. Just about to drive 300 miles home, so shall ponder more on the way.

Welcome. Your current DHW setup, and lifestyle are similar to mine. I have an E7, 200lt cylinder, but most of the time I could get away with 100lt. Now I very really need to top up my cylinder because it runs out of hot water. And I only heat mine to around 45⁰C. If I do top up, because I have friends staying, I just turn the top element on. 30 minutes and the job is done. So I would wire the PV diverter into the bottom element, and out the top element on the E7, but with a secondary timer set for the last hour I.e. 6AM to 7AM. I use a pumped shower, it works well. Cost 100 quid for the pump, and not much for the tap with a shower takeoff. With the RCD and pipe and stuff, less that 200 quid. That was 15 years ago. Spend all your money on insulation and airtightness improvements. The only bit of hi tech you need is an energy monitor and logger.

Was more a general comment for all jobs. Molegrips as well.

I think the idea is that they are under the scrutiny of the correct organisations. One of the problems is that the product may then be used incorrectly. What we don't want is a system that take decades to develope and approve all new products. Medical licencing is like that. But it is all irrelevant as we will be lowering most standards now that we are not shackled by the EU.

Angle grinder and a cutting disk. The only other tools you need are a hammer and a screwdriver.

@Iceverge I have to agree with you in this. What I did and in my second year halved my energy bills. Starts to get harder after that, but down to about a third of what I used to use. But. If changing a DHW system anyway, worth looking at something like an Ecocent, especially if it can be fitted in, in part, with the MVHR i.e. take some if the exhaust air and pull the energy our of it (why don't we already have MVHR systems that do this, we have them with cooling HPs in them). There does come a point where energy scavenging just becomes that, scavenging. A Cornishman is just like a Yorkshireman, but with all the generosity squeezed out.

Short of hydrogen replacing all mains gas, and that would cost about twice the electrical price per kWh, we are phasing out gas. Just design your house to use an ASHP from the start. If your architect and builder disagree, asked them to do some long term projections on energy and technology prices, or tell them to stick to drawing and placing bricks in place.

How easy is it it to make an isolator that will stop power going back up the line? In small circuits Zennor Diodes are used, is there a larger scale equivalent? The trick is to still allow incoming at the same time as discharging the home grown.

I can ponder for decades.

Can't you plumb something into the CH circuit. A store and a plate heat exchanger.

Why not fit one. Probably a lot easier to fit, and cheaper, than batteries.

Yes, and if it starts discharging though the export side of the meter, you would probably be breaking the terms of your FiTs. The Spanish had a habit of running diesel generators though the export meter at night to claim extra cash. It does all depend on the set up though. But if you are already exporting 75%, get some diverters.

Yes, but not easy to do I suspect because of the safety and quality of supply. Most battery charging follows an exponential curve, so as the battery gets 'fuller', the rate of charge diminishes. Trouble with PV is that you cannot guarantee that when you want a lot of power, it will be there, and when you don't want much, it won't be there. This is why they are grid tied, it improves the quality of supply i.e. consistent.

Fairly complicated, but no more so that diverting excess PV to a water heater. You may need to isolate the battery system discharge until it is dark, but that is a simple light sensor. First thing to look at is how much, and when, you actually export. If you are not exporting much, it is not worth it.

Makes a new module less than 2p/W more expensive. Before VAT and delivery that is.

What do you actually mean by 'heat'?

Have a look in the user manual, they often write it down in there.

Bipolyol. Unless they are Welsh, then Dipolyol.

It does depend on the absolute flow temperatures and the outside air temperature, and if the auxillary resistance heater kicked in. Getting 2.5 times the energy input seems OK to me. And it is kWh, not kwh.

It is to do with the way the chemicals react and cross link. I never remember which is which. I think PIR reacts more during formation as the cyanide group reacts with itself, rather than just then polyol group. It is a fair few years since I played with them in Castle Donington, was fun though, had a brilliant chemist there that was excellent at explaining it all.

https://en.m.wikipedia.org/wiki/Coefficient_of_performance