MikeGrahamT21

Ducts definitely need insulating, or burying under the insulation in the loft. I think the manifolds have a small amount of insulation in them for acoustic purposes, but not sure how much it provides for heat insulation. I suspect if you can build a box and insulate it around the manifold, this would probably be the best option for minimal heat loss, this is what I plan to do, just becomes a bit of a pain taking it all back out in order to do any cleaning

I dont think it would matter either way, it'll be virtually the same temp. Almost zero heat input from interior of the house, some roof membrane and tiles isn't going to hold the temperature that much higher than external.

Yes you do need a lot of them, but maybe not as many as you think, and it doesn't take long, but its worth it to do a proper job. And the load they suggest is more to do with the ceiling joists than the loft legs themselves, its called covering their backs. I have loft boards up there, which are a quarter the size of full sheets, and there still wasn't that many legs for the area. You talk about the loft as being somewhat warmer than outside...when you've packed all that insulation in, it'll be virtually the same temp as outside, as thats kind of the point in doing it.

I think they can be a weak element, from an airtight perspective, but I think the angle of the glass has something to do with it as well. Maybe a more important thing is that they are well balanced in terms of energy value, as they let potentially more energy in than they let out. In terms of pure glazing value, compared to a normal window, they are a weaker element, hence why we are seeing 4G and even now a 5G from Velux. I have some older 2G (probably around 2.0U) Velux, and newer 3G (1.0U) Okpol windows, and the difference is immense. All south facing, but the frost stays on the 3G for considerably longer than the 2G. Also measured glazing temperature in the summer, the 2G can be 20C higher than the 3G panes. Quick measure on temps now, with outside around 5C, the 2G panes show up at 17.7C internally, 3G panes at 19.4C and the internal room temps are at 19.9C

Kingspan use purlins as its required for structural purposes. Oh and you'll probably find that they use insulated panels which sit on top of the purlins, and screw down onto them, i.e. removing the thermal bridge.

Just use loft legs, far better at the job and designed for the purpose. Metal is one of the worst thermal bridges possible, you may as well not bother with the extra insulation

I would say 0.15U target will be a cause for concern on the structure of the building, needs calculating very carefully to avoid any risk of condensation. Do you have any option to do External Wall Insulation?

+1 for MLCP Pipe. I got 16mm pipe, manifold with 16mm eurocones, and eurocones for all of the radiator ends, and ran full lengths from manifold direct to rads. No joints at all, so no ability to leak in horrible hard to reach spaces! Using plastic pipe can be a bad idea for radiators, as the integral oxygen barrier of things like JG tend to only work up to 50C, which most heating systems will run above. MLCP has an aluminium liner, so doesn't suffer from this, so overall things should last a lot longer, and as a bonus, if you have any mice knocking about, they shouldn't get through aluminium.

Yeah loft legs are brilliant, i've just done half of my loft out with loft leg XL which allows me to get 400mm in there, they're a small premium over the standard legs.

I'm sure you'll check it less once the novelty has worn off, i've been the same with heating controls and solar generation, but its dropped off more recently. Really interesting hearing people talking about how the MVHR helps greatly with holding temperatures, an effect i didn't realise would be so pronounced. I'm considering installing a unit here next year, or possibly year after depending what happens in the coming 6 months, though i'm not expecting such great efficiencies, as I'm far from airtight at the moment (Only 2 rooms and a hallway is truly airtight at present, another 5 larger rooms still need doing, though only one out of those is really poor for airtightness).

I haven't got MVHR yet, but I also plan to get to radial anti-static and anti-bacterial ducting. I have read articles in the past in building magazines about nasty bugs being found in ducting of MVHR due to the temperatures which run through it, so I would say its critical personally, and for the little extra outlay should be worth it. Anti-static should prevent dust from sticking to the inside of ducting in theory, it will still get there, but should be much reduced. I too keep looking at fancy controllers, in fact i've actually made it one of the things on my wish list, but in reality I dont think they are needed, I'm pretty sure a good MVHR unit should be a fit and forget solution, which shouldn't require controlling if its setup correctly, many have sensors built in to handle differing conditions, I suppose the only thing which is useful is the filter change reminder, but you could set a reminder on your phone as its based on operating hours. Perhaps a unit which connects to your phone rather than has a control panel may be a better option, but these are hard to come by at the minute.

Angle is definitely a huge influencer. Length of day again a massive factor.

Go with concrete every time i'd say. I have timber joists in ground floor, and though i'm very thankful with it being 1960's, that i don't have to dig up old concrete to insulate it, you always have thermal bridging with timber, which you wouldn't with concrete, plus the thermal store as you've said. With timber there is also the element of ventilation to consider, which you wouldn't with concrete, and depending on what timber they use for it, the chance of insect attack, woodworm is horrible!

Pop the control panel off of the wall, should be a screw or two underneath, and it'll just lift off, couple of seconds then put it back, that should do the trick.

If I remember right MVHR units use old fashioned COM style communications, these generally require that one end is powered on and operational before the other end is switched on. I would guess that the MVHR unit needs to be on and fully booted (give it a couple of mins to do this), before the control panel is turned on, essentially so it has something to connect to, it may only try once and then fail if it can't connect.

Have you checked seconds and co for the insulation? You may be able to get phenolic insulation at a much cheaper price than PIR, and it tends to come in pretty much perfect condition, could save you a small fortune. I recently bought 21 100mm boards for a little over £400, retail these would have been astronomical.

I’d say just some plastic sheeting to stop the water getting in will be the best thing, it’s the combo of wet and freeze thaw which has potential to damage them

Since presumably you are installing Solar PV for environmental reasons, then go with less panels which are better, as they will have less embodied carbon, and all of the other chemicals and rubbish which get created during their production. And if nothing else, its less bits to go wrong!

Thats a real shame it requires planning permission, i can understand it for a proper bay, as it will have foundations, but didn't think this would need it

I'm going to keep an eye on how this turns out, very interesting. I currently also have a bow window, but would like to replace it with a normal flat window, which is hung further out of the brickwork, partly to keep it a little more in line with external wall insulation, and partly to keep the deeper cill. I'm curious though, would this type of thing have to go through planning permission? I know for a proper bay window conversion you have to have planning, but I wonder if this would be covered under PD?

I did the utility with 20mm plastic conduit, and then got an electrician in who used singles, he said it would have been a lot easier to use 25mm conduit, and thats what he would have installed. Even so, the conduit houses sockets cabling 2.5mm and a lighting circuit 1.5mm, but it took them a while to thread so i'm guessing it was tight. I'm not sure if this helps, more of an observation, i put another run of conduit in for ethernet cables, and managed to just fit 4 of those down, so you don't have a lot of room to play with

Yeah good idea, I’ve got smart TRVs in each room to do the same job

Yeah I think I’ve one Blu-ray which has got it, a Harry Potter if I remember right, there is a lot of simulation stuff as well though like DTS Virtual X which is meant to be really good. I think for £99 it’s a sound investment. Glad to hear it works well in a real life situation too so thanks for that

So the IC600's were a bit bigger than anticipated!! Think I shall be returning them for some IC400's tomorrow.

What rate do they pay the export tariff at for new installs these days? I just got £27 export for the last 3 months on my 4kwp system