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All walls including studs Did ours yesterday

Agreed - it's don't sweat the small stuff territory.

+1. I don't see those things pointed out as issues at all. I think it looks really nice.

Or just need to get people used to operating the heating system as one or possibly 2 zones only. Then there is no need for a buffer or any form of indoor unit, just a 3 way diverter, to the heating system and the DHW system. Run on weather compensation or a modified curve to use almost a batch heating style in the shoulder months to overcome short coming in the modulating range of the heat pump.

The 600m of FTTP ducting put in for my property was 54mm grey duct which you can buy online. https://www.drainagepipe.co.uk/bt-duct-54mm-x-3mtr-grey-p-BT54/ They wanted to put a telegraph pole next to the boundary and then on the final install run a cable from the pole to the house but instead they agreed to leave me the 54mm duct and I dug for and buried it myself plus they saved a pole. You also have to install a pull cord (2 is better) for them to pull the fibre through the ducting.

It's a pretty rare ground floor window where the floor level inside is 600mm + above the external ground level. So normally the requirements of part K apply which says you need guarding if a person can fall more than 600mm. So, if your floor level is say 200mm off the external ground level then the cill height of a window can be at any level as you cannot fall more than 600mm..... If you want to keep to 800mm high cill heights at first floor level, restrictors will only work if the openable area with them in place meets the requirements of the openable area needed. Otherwise guarding will be needed.

Our heat pump, will follow a heat up curve, it's a matter of being able to take away the heat effectively, otherwise the you move heat around a system and it doesn't get to where it needs to be. That's why it's best to limit zones etc. in the heating system. But boilers are the same, it's just that gas has been traditionally very cheap, so really bad installs go unnoticed, by the owner. Another thread today mentioned oil boilers are 93% efficiency, but in most installs with loads of thermostats and an oil boiler limited or none existent modulation, short cycling is the order of the day unless running against a large thermal store. Would expect in this installs 50 to 60% efficiency if your lucky.

Appropriate flow. A 3, 5 or 7 degC dT (probably the same dT both sides unlesss primaries are particularly long?) at the target power output ought to give optimal COP improvement for minimal pumping power increase. You can't run at part part part load though. And not do you necessarily want to run at 11/10ths either.

I would measure from existing floor level upstairs to the underside of your soffit. Then subtract 388 to 400mm for the following.. 150mm - upstand for flashing the flat roof to the wall. 25mm - Waterproof layer and 18mm OSB. 50mm - Ventilated air gap 150mm - PIR Insulation between rafters. 1mm - Vapour barrier 12mm - Plasterboard. Total 388mm See what that gives you. If its less than about 2.25m you might need to look at trading off headroom downstairs by lowering the first floor so there would be a step down from the bedroom into the ensuite.

Well we may rethink the bricks, just won 3 pallets (36 sleepers) for just over £350. We only wanted 20 so I'm thinking now of creating a shape around it with the sleepers....

You will need a compacted sub base to stop gravel migrating into the soil, if your soil is compacted enough then a membrane is required to stop stones disappearing into the soil. yes the dust and smallest particles will settle to the bottom leaving the larger, cleaner stones on the top.

Gravel goes downwards. Why you get dust at the bottom of the cornflake packet. Charles Darwin did studies about rocks in soil.

Yup, good enough is good enough. Better is still better, but can be sold as a business case led upgrade. They already can. Check out the Vaillant R290 units - flow temp goes to 75C. One wouldn't necessarily design for this, its almost certainly preferable is to retrofit a PHE to the existing cylinder to increase the 'coil' area without having to rip out the cylinder yet still allow the flow temp to be 55/60. The technology for mass retrofit is here now; we need fit-for-purpose regulation (or better still scrap MCS altogether) fit for purpose planning rules (PD requires MCS and excludes most if not all 2-fan units. MCS-rules-based over sizing drives installs for larger retrofits to a 2 fan unit, LPAs then object to the noise even though it meets the PD noise rules so legal install becomes impossible or impossibly difficult a fit for purpose system design industry By the time the UK has those, the technology will have advanced even further, perhaps to the point where our under-educated construction industry can cope with it without completely messing it up. There are no excuses left, its all within UK control.

It's ok, I really just used what I already had. Used really as a proof of concept, the thermal store is only 180l so there isn't a big reserve of heat for DHW. If it was an UVC the concept would be better. PHE is really the wrong side of the diverter valve to use for defrost. Trouble with the heat source it just wants to make dT correct all the time. If the dT is low it just ups the discharge temp to compensate, so you soon get to max discharge temp and the heating cycle stops. Then you are into short cycling. Without a pump in the system the water transfer via thermosyphon is not controlled and likely to be too slow.

I have an external PHE connected to heat a vented thermal store. It takes water from the bottom of the store and it is pumped through the PHE to the top of the store. Heat is provided by a 6kW ASHP. The PHE works in a similar/same principle as a mixergy one does. The thermostat located about 40% up from the bottom of cylinder is set for about 42 degs. Heating cycle goes something like this. Cylinder PHE pump starts, and ASHP starts DHW. Cylinder becomes unstratified, overall cylinder temp drops as water from bottom and top of cylinder mix. Heat pump gradually ramps up temperature of its output to maintain a 6 deg dT. When it gets to about 55 deg the thermostat is made in the cylinder. The heat pump stops Over the next 20 mins or so the cylinder re-stratifies with a temp of around 50 at the thermostat. If I reduce the PHE pump speed heat transfer is not as effective and the ASHP cannot heat the cylinder to satisfy the thermostat set temperature.

You'll never get that. It'll be 18-20c almost all of the time, through every room in the house, regardless of what heating plan you have. Our bedroom is always in that range. We just use a light summer douvet all year round, and sleep on top of it a fair bit. It's different mindset and you kinda have to live it to understand. I wear shorts and t shirt most of the time inside, all year. Only in the office room I'd need to stick a hoodie on for in the winter as it's mostly glass and doesn't have heating, so would be 16c in the morning. And all this for about 1/4 the heating cost of a "normal" house.

Knock it down and start again.

@jon3 The house I grew up in was regularly 12deg overnight. Icy noses and fog from your breath, mould on the walls and everyone always had a cold. The only practical way I can see happening for a modern building is to make an uninsulated "storage space" in the attic, plasterboard it out and use it as a bedroom. Ensure you have a huge amount of ventilation however as it'll quickly get mouldy otherwise.

The beauty of oak is that it weathers to a silver colour and doesn't need any treatment. It's quite acidic - you need to use stainless fixings, A4 rather than A2 if it's not too expensive. I like to do things only once - so I used oak for our raised beds etc. If you paint then you'll be painting every few years, but if you insist then I would use Bedec 'Barn Paint'.

welcome. as above turn-key is generally the most expensive way of self-building. we had quotes from ScandiaHaus for our build as turnkey and it was super expensive. so much so that we're hoping to bring the build in at less than 2/3rds of the cost they quoted. but we've been very hands on and done a lot of the work ourselves and it's taking a long time as a result. remember the triangle of building. time, cost, quality. you can have 2 of those at the sacrifice of the other one. so we want low costs and good quality so it's time that is losing for us.

You are looking at a turn-key build, nothing new but usually the most expensive way as you don’t do anything apart from say what you want. loads of info on here by searching old threads

OK just to report back - for anyone else needing these kind of services. I used these guys: https://www.fiverr.com/quark_visuals - and they we're professional and reasonably priced. I was careful to write a 8-page brief specifying my objectives and the exact viewpoints and another 7-page brief on materials (lots of images in both of these). They were careful to do quick mock-up images to verify the content / viewpoints etc which I thought was professional. I supplied the CAD models from Fusion (actually in sketch-up format) and the block plan drawings for positioning. The objective wasn't to make the whole thing 100% photo realistic (actually better so the split between what is rendered and what is original image is clear) but to demonstrate what the casual viewer would see looking at our proposed build in relation to the farmhouse 'heritage asset'. There was a bit of flexibility on both sides - I asked them to add a driveway and adjust some colours and I put up with some small image artifacts (which are inevitable with this kind of image manipulation). I chose to build on top of Google street view images (which were fortunate as they were taken on a sunny day). These are not the best quality, but it does allows the LPA to verify the images. Here's the kind of thing - our proposed building is on the left:

I like to think of it simply. Coil for heat pump, coil for solar thermal. Set ASHP Stat as suggested at 48/50 degs. Base case, ASHP heat tank to 48 deg. If solar heat availability is there, have a separate thermostat, to allow tank to max heat the cylinder will allow. You can achieve this with an unvented cylinder or thermal store. Next question is do you need a buffer for your heating? If so, this could use the volume of water within the thermal store as part of the heating circuit. A two port valve and pump controlled by your central heating thermostat. Your heat pump only has to heat water in tank, no sanitiser program required, as DHW flows through a coil in the thermal store. Why do you need to monitor water temp at different heights?

It is why I very really mention price when talking about renewable/low carbon generation. But if you take the drastic costs reduction that has happened with PV and Wind Power, and how it has happened in a decade. Heat generation won't be far behind. I hope so, only go tot look at all the countries that are suffering from the exceptionally hot Northern Hemisphere summer this year. USA, Southern Europe, Central Asia and China. If we think it is expensive to fit a heat pump, wait till the costs of crop failures and migration take hold.