PeterW

Ahh ok ..! I know the GHG was initially only to 2021 but has been extended. Didn’t know RHI had also been extended

That is the green voucher scheme that they have now extended for 12 months.

Can you draw a rough plan ...? How far from Rayburn to thermal store for example ...?? TBH if you want to just warm the place, a single pipe running from rad to rad would be fine as it will be easy to install. If you want the ability to isolate rads then you’re better running a pair of pipes for flow and return. Thermal store shouldn’t need expansion as it’s either built in or the expansion tank should be above it (or it’s just become a very dangerous sealed unvented cylinder ..!!)

I’ll see if I can find the curved wall photo I took ... 4ft radius curve on the outside and a 45 degree wall on the inside ..! Was enough space between the skins to stand in and they did nothing with it ..!!

These guys - they also do the adapters for the valves as some may be non standard threads. https://www.radiatorvalves4u.co.uk/trv/radiator-valves-accessories.html

Some you can, some you can’t. The Wunda ones are good value as they have interchangeable connectors so you can mix and match hence why I suggested them.

Don’t use lightweights as they absorb water like a sponge. Get the cheapest nastiest concrete blocks you can find - lay them all on flat unless you can get 150’s as single skin of 100mm at 2 metres high is very thin and will catch the wind.

Just use the builder cheap $h!t between the rafters and then put the decent stuff on top. You can stand on those rafters - they really will take your weight ...!! 250kg hot water tanks only get spread across 4 rafters for safety factor, they will comfortably sit on 2 with no issues and that’s a permanent load. Just don’t jump between them..!!

OK ... First layer should be between the joists and you just need to put cheap clay plant pots over the tops of the downlights to stop them overheating. Next layer of 200mm goes across the joists and covers up the first one. Last layer of 100mm goes across the joists but staggered over the previous layer so it stops any gaps straight through. Get it tucked to the edges but not too tight so that you get the benefit. Don’t think you’ll need more than a couple of big rolls - £12 or so in Wickes.

I have 400mm in mine and trust me it works !!! Yes it would have the same fluffy stuff, it is around 1/3rd as effective as PIR for the same thickness hence needing about 3 times the thickness. Your issue is the big stone walls - they are sapping the heat so every bit of insulation elsewhere is helping. They need to be your next project to get the walls insulated and the gaps for the wind to whistle through blocked up.

Not too difficult - should be a link in the box below where you are typing with the paper clip next to it. Click on that and you’ll get some options Select from your photos on the iPad and then click Add at the top of the photos (or use the camera) and then the photos appear below the editing box To add an image you’ve uploaded, put the cursor where you want it in the text and click the “+” button, if you’ve uploaded the wrong one just hit the bin button and try again Simple as that ..! And welcome aboard..!

Polypipe manifolds are crap... and expensive crap too ..! Save your money and buy from Wunda or one of the other online suppliers If you’re having a manifold that will be controlling / supplying each radiator, why do you want rad valves at the radiator end ..? Flow control will be done by the actuator and the flow meter so you don’t need valves. These would be fine https://pswtradesuppliers.co.uk/brass-compression-fittings/78-16x12-male-elbow.html

At two cuts a minute, there is probably 4 weeks work solid cutting 13000 bricks down.. and a couple of blades ... and a lot of ear plugs ..!

Armaflex or Insultube are the two nitrile ones.

Just for info, Climaflex isn’t rated for outdoor use - you need a nitrile rubber insulation preferably with a jacket or coating.

Have them inside not outside.... just put a pair of connections through the wall

I’d just make the B1/B2 en-suite into a Jack and Jill and make it a touch wider - sink next to the loo, shower in the alcove and doors opposite each other. Lots of wasted space in the main bathroom - skim it down and use the space in the B4 dressing / en-suite. Don’t like that you have to walk through the kitchen to get to the utility and it’s the only way to the outside at the back. Flip the stairs and look at how you can get the downstairs loo under the stairs - there is a window there already as the architect can’t draw as currently you’ve got a square window (right of the rear utility extension) smack bang in line with the first landing of the stairs.... I’d flip the kitchen to the dining end, would work better with the layout. Dining then is lined up with the lounge area assuming they are open plan ..?

Looks like that is too close to the wall (min 300mm) and it is also out of balance - wonder when the fans were cleaned last .? Noise will be amplified by the wall and the fence - quickest fix is turn the ASHP 90 degrees to the wall(s) and it will reduce the noise substantially and probably improve the performance too. Out of the box it’s 52dB so it’s definitely louder than the agreed level but that install doesn’t look good.

Fluffy roll, yes. PIR, No... as you don’t have the access down the sides of the skielings to insulate them and join it up so fluffy roll Is your friend. Get a big plastic sheet to cover the floor too as you don’t want it in the new shag pile carpet as it’s a nightmare to hoover out.

7kW isn’t that big - radiators or UFH for heating ..? How long are you running it for and how big is the house ..??

Let’s take bets that the builder put 100mm of fibreglass across the rafters .....

And then another 200mm on top ... ? @zoothorn where is your nearest Wickes or B&Q or are you only able to go to Jewsons..?? Ideally, you want 3-400mm which is 3-4 layers of 100mm, but you can get it in rolls of 200mm thick. First layer goes in the gaps between the joists, then the rest goes straight over the top up to the edges. It doesn’t need to be neat, and a 3m length of waste pipe is ideal to shove it into the edges where you can’t reach. More the merrier, just don’t block all the edges completely tight to the white membrane. I’d you’re clever you don’t need to get up there apart from to put some plant pots over the downlighters as they shouldn’t have insulation directly over them. You can do that by kneeling on each of the rafters as you go.

Even more important is that as they get closer to the target temperature the water returning from the floor is warmer - the delta reduces so the heat input required is modulated down to hit the target flow temperature. The issue is that a heat pump has a minimum flow and minimum water heat input, go below either of these and it will shut down so blending valves allow for longer gaps in the shut down (less short cycling) and less impact on the ASHP. It’s called basic system design. It is the review of the requirements such as combined flow rates, number of concurrent showers, peak flow demand etc, and the space heat requirements of the build to get to an optimum target design. There is however a common myth that combi boilers give “mains pressure hot water” and that equates to a high flow of hot water. I can assure you they can give mains pressure but they can’t give “mains flow” as they all have flow restrictors so that you can have 3 Bar of pressure but only 12 litres per minute - and flow is what customers want for showers. Couple that with the issues of requiring low energy houses, PV to meet SAP scores with no FiT so looking at self consumption, and you’re into a realm of big stores of hot water (welcome back to the 1970’s of hot water designs..!!) with low density heat input sources ..! It is a minefield and it’s no wonder that it is badly executed - combi type performance from a heat pump without resistance heating to boost flows is the holy grail !!

Drill a few holes just above the DPM on the outside and let it drain using some of these if you are really worried. Get a DPM over the cavity to stop any more rain ingress https://www.ebay.co.uk/itm/Cavity-Wall-Round-Drill-Weep-Vents-Refurbishment-Retrofit-Various-Colours-/184213149281?_trksid=p2349624.m46890.l49292

Thanks Mike - I may do that ! They list it all as PEX now which is what I thought - will see if they have any certificates for it now as need to specify those normally.