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Very good example in the first post. But I think dogs are a very expensive method of heating Way more than direct electric! My boss makes a point of inviting guests most weekends to his house in winter. I think it must be to get free heating I did a similar thougth experiment with my house design to prove the level of insulation it required to not need a conventional heating system. Of course, this means the house will most likely have an overheating problem when south-facing glazing is considered - hence the ducted air conditioning throughout. (It heats efficiently too.) There's quite a saving in complexity by not having radiators, UFH etc, especially when you consider MVHR requires ducting anyway, and with proper sizing and design the A/C and MVHR can work together with virtually the same amount of ducting. The main driver for my build (300m^2) is indeed air tightness, and we are taking great pains to minimise this with the SIPS supplier - getting this right ought to give us another 3 months per year of no heat requirement.

The not-quite-matt, not-quite-gloss finish. It always seems to conspire to look slightly dirty. It's probably in part predjudice from my first flat in London that had been badly decorated with eggshell before we bought it. But as SiBee says: Opinions eh.

The very paint I dislike the most!

I've yet to find a modern white paint for wood that doesn't go a horrible yellow or have a nasty rough finish.

I have lived on the Island for 20 years. It's the first question when buying anything. The current bath was a gem for this. Free to Southampton or £300 from Southampton to East Cowes. I liked the look of the Rationel windows, don't get me wrong. But I have a desire to not have too much maintainance. (I dislike painting windows even though I can do it reasonably well)

Their website indicates they make exactly what I want - UPVC or aluminium frames with decent opening sizes. But I read on other bits of the web that they haven't in the past been easy to deal with. My architect is suggesting Rationel, but I am not so keen on timber/alu so we are exploring alternatives. And does anyone have other (not silly cost) suggestions? Thanks

It is an interesting offer, especially for me at my current state of build. But they aren't giving much away are they? I suppose the argument is that they are servicing it for 10 years. And they are designed for a different usage profile. Peak currents are very different between battery based energy storage for houses and the use (or abuse in my case) batteries in an electric car see.

I'm with you on that! Instant is horrible. I like my Aeropress. I can move it between work and home easily, and it's sailed nearly half way around the world with me. And all things considered, it's cheap, even if you do need to use a kettle. I like my espresso perc pot too (a habit I too collected on holiday in Italy), but it's too much effort most of the time.

Thanks! That's really useful to see. (and it's nice to get confirmation of not being totally crazy!)

I have a site with lots of oak trees on high shrinkage potential clay, so I have opted for a pile and ring beam foundation with a beam and block floor. I seriously looked at a passive slab, but the costs associated were prohibitive and there's very expertiese here for such schemes. I am seeking to achieve a very good level of insulation - my target for the floor is a U value of 0.1m/m^2. If I use traditional beam and block with 150mm of kingspan on the top I can achieve this. I then looked at a scheme called "Tetris", that promised a very insulated floor, dispensing with the blocks. (There are loads of this sort of product, this is just one example.) I looked at the specs and found that if I used Tetris it would sit 150mm above the beams (the same as the Kingspan) but only achieve a U value of 0.2w/m^2. So near double the thickness and half the insulation. I could get to 0.13w/m^2 by 75mm of additional insulation but why would I choose this over the simple traditional method? Am I reading the specs right? It doesn't seem right somehow - where is the advantage in the new method, other than not having to lift loads of concrete blocks?

Not something I would want to do either. But if we ended up with something that would pass then it remains an option. I have done such things at work for very low volume stuff. There's no wonder defence equipment is so expensive... Definitely an "open" project. But we aren't calling it an "open dump controller"! The idea would be to get a good flexible circuit board made with plenty of the right sort of I/O so that it needs a little work for the particular installation, but the tricky soldering is done so you were pretty sure of getting something that worked. I worked on an open source engine management system a few years ago and this scheme worked out pretty well. Totally agree here. I'll have a think about a cardinal point specification when I get a few spare minutes. I'm thoroughly worn out tonight after an afternoon of tree surgery. PPE is unpleasantly hot in this weather. But more pleasant than the alternative of course.

I know this is quite an old thread but I'm still catching up on what's available in the market place and what things people have done. I've done a fair bit of microcontroller work, mainly WinAVR targetted at Atmel ATMega chips (same chips as Arduino use, but for a lot of my designs I couldn't afford their library overhead so I never bothered with it) and it's usually been enjoyable, apart from chasing that rogue interrupt that you mistyped that makes the whole thing do something really odd... I wondered if it would be worth "productionising" a solar diverter design a bit based on the @ProDaveand the @JSHarris designs. It wouldn't take me long to draw and manufacture a double sided PCB and populate the tricky SMT components for this project and it shouldn't cost too much if there are more than 3 boards made. (The electricity meter chips are mostly SMT these days making them less DIY friendly) It could have a few standard interfaces - either industry standard or we agree them here - and a number of useful outputs (DHW and battery charger switching is probably enough) plus data collection to say an SD card. We would then have the advantage of sharing a common architecture so that we could all contribute to developing the design - the idea is that what helps one will help all - and of course we would all know exactly how it all worked.

Physics is not a problem. I have a couple of qualifications there... It's having to back calculate all of the manufacturer supplied data to find their definition of an apple and seeing what simplifying assumptions the tests allow/force them to make that's annoying. For instance SAP ratings aren't really helping at the end of the scale I (and others here) want to work to.

That seems to be the really hard part about this whole house building thing! The wife pretty much does that. An insulated bath can be enjoyed for hours apparently...

I think so. Or at least the option is there to do that if you put enough energy in to it.

Do this around the outside of the bath too. The wife won't complain about it. I wonder if you could arrange for a 2 compartment airing cupboard? Although it might be too difficult at a late stage in the build... Something I could think about though.

I a similar one in the solar thermal thread. If I used twice as much water, solar thermal became cost effective in my DHW model... But let's not open that one up again. Nice plan with the E7 use. I was looking at writing a control system that looked at what the likely morning water use would be, took a guess at how much sun there would be and then heated the tank accordingly. If it was wrong then it would correct itself by using high cost electricity to support the evening water use.

So why does a UVC come out so much better than a thermal store? Is it simply the temperature doesn't need to be as high to deliver the same water? Or are they built to a better insulation standard? If I'm feeding the UVC with the same inputs and using the water at the same rate, why are the losses wildly different? (Assuming equal volume and surface area of course) Either way, UVC or thermal store, it doesn't matter how much insulation is put in if the heat can't be removed eventually. Hence the idea of extraction. Sunamp is a strong no at the present time. In my opinion the technology needs time to mature for it to become properly refined - there are far too many subtlly different options to pick from and they are probably all the same inside, but for a (no doubt very expensive) bit of software on a microcontroller somewhere inside. And they are an expensive way round the problem right now. Once they get cheaper I would certainly reconsider.

Thanks. Those losses do seem really high compared to your usage. I estimated the family usage quite a bit more than that (but perhaps it's more people and more teenage daughters...) It would seem the losses are trying to model heating with a system boiler and then using the water shortly afterwards - making the test temperature much lower as you say. This isn't the way a store would be used in any sensible low energy house. So the plan has to be to insulate the tank as much as possible. I should ask the SIPs people to bring the larger offcuts with them - there's bound to be some scrap pieces that would be big enough to make a thermal store cupboard. If I can use the same stuff as the roof I might be able to get losses down to 0.5kWh/day.

Thanks. Just the sort of thing I am after, That's just less than a 100W light bulb in there on the whole time, assuming 1.95kWh/day. It sounds like it is an over estimate to me, although it depends how well insulated the cupboard is.

Not the main cold tap. It fed all the cold taps in the house except the kitchen. I got mightily fed up with having to descend 2 floors just to get a drink of water at night. The current house had so many plumbing problems that you wouldn't believe possible (It was built in the 80s recession) and the silly water softener was the least of the problems. Things like the pipes from the cylinder sitting 20mm above the floor joists! Essentially, I hate the water softener. I can fill it up with salt easily enough when I remember, but there must be a way to design out needing one since it only does half a job and causes other annoyances in the house. Descaling one side of a single heat exchanger once in a while seems a much simpler idea. I understand that. It's not the question I am asking. I want to know that if a manufacturer says a product loses 2kWh per day, what were the conditions of the test? Are UVH and thermal stores tested with the same standard test? Can I believe the manufacturers claims or is it designed to allow them to claim good performance but not actually deliver it? (You know, like car MPG figures used to be measuered) And above all, does the thermal store (or UVC) meet the manufacturer claims in the real world?

I have a water softener in the current house. It is annoying to keep it topped up and it makes the water taste bad so I had to re-arrange the plumbing to put it on the feed to the boiler only. And it doesn't eliminate the problem - it merely extends the intervals between having to put the boiler heat exchanger in the untrasonic tank! This is a side issue - I would primarily like to understand heat loss measurements from thermal stores and UVCs to decide what I need to design in to make the DHW efficient.

Reading a few threads on here suggests that thermal stores don't have a good track record for having good insulation and low heat loss. I would like to understand how bad this is because as far as I can see, it is going to be the single biggest cause of my new house overheating in the summer. (In the winter I could be persuaded to install an extract vent to the MVHR in the thermal store cupboard to heat the whole house! ) The lack of insulation is not necessarily a problem if I know about it now and allow space to build a cupboard with additional insulation in the design. But the key thing here is why can I seemingly not believe the manufacturer data for heat loss? Is it some obscure test where the thermal store is tested when it is only half-warm? If I could understand the test then I might be able to use this to design the additional insulation. Or, even better, does anyone have any real data about how their thermal store lost heat? Note that I live in a part of the country where the water is hard, bordering on agressive, so this makes me think a thermal store might cause fewer problems because the bulk of the limescale is contained in only one heat exchanger rather than spread throughout a cylinder.

And this is the whole point of smart meters. It's certainly not for our benefit!

A quick update: I spoke to a local business and their initial response is that I can achieve the desired result, and if one of the major suppliers were to market a product that does this, they would sell loads of them, The sticking point is the control issue. We both believe this to be a soluble problem even if it proves a bit tricky involving some form of building management system. We went over duct and terminal sizes and air flow requirements and found that my air flows for the heating and cooling were substantial over-estimates. This is good because it allows the ducts and terminals to be reduced in size and substantially narrows the flow difference between "just vent" and "purge with full heat". We even found a few tweaks that should help with efficiency and comfort - more on these later if they stand up to scrutiny. They are fairly comfortable with being able to get something that doesn't need motorized dampers (the "simple usually wins" argument) but I would like to have the option for zone controls, even if they are not fitted when the detailed design proves them unnecessary. These would be located in the plant room on the ground floor and airing cupboard on the 1st floor.