JohnMo

As far as know anti freeze valve are basically anywhere in the outside pipe work. I would place close to the ASHP though. I know the advantages of anti freeze valves, but I chose to just install 20% antifreeze. Worst case for me was, I was away, anti freeze valve opens, heating system depressurised, wife can't, repressurise heating system, so heating remains off until I get home. Me in dog house. Strainer should really be inside not outside. But accessible for cleaning. Same for fill valves. I have my isolation valves direct to heat pump. But depending on pipe length outside, they could be immediately inside house. Remember you need an expansion vessel. What's the pressure reducer for?

View in front of panels, looking SW.

Just re read my first post PV panels are 280W not 380W so 3.3kW total. Yes correct. My existing array gets 99% utilisation in summer, but stops producing anything meaningful at about 3pm. With the additional panels my summer output should stretch out to about 8pm. Yes I do, miss out on huge amounts of unpaid export in the summer, that was accepted, as I really wanted to maximise winter generation, to offset ASHP running where I can. December monthly generation goes from 30-35 to close to 80-85kWh. View directly above array.

PV panels will be circa 60m from house. 2 PV arrays to one inverter. Inverter can be located indoors or outdoors as long as it has a rain cover over it. So question am I better to locate the inverter next to the PV panels and run 3-core 6mm2 armoured cable, to consumer unit? or run DC (4 core armoured) to inverter located near the consumer unit? If DC anyone know what size cable? In both cases the armoured cable will be surface run, except for a short section under a path.

Forgot to add cost of posts and postcrete. Circa £400. 8 x 2.4m and 8 x 1.8m posts and 24 bags of postcrete. Screws etc are just left overs from other jobs. Unistrut, 42 X 42mm x 6m, 5 off required, M8 spring nuts, £300.

Decided to add to existing roof array. Roof array gets quite a bit of shading from trees and especially in winter ends up with a very short solar day. It faces south east. New array will be ground mounted vertically, more optimised for winter generation than summer. The vertical is also to protect from bits that can fall from overhanging trees. So doing it on the cheap and myself, except the electric hookup. Panels 12x 380W, 2 years previously installed life, bought for £700, plus a 3 hour drive each way to collect. Inverter (solic double mppt) again previously installed for about 12 months, bought for £150, collected on way from work. Isolators AC and DC, generation meter, stickers and MC4 connectors, £99. Mounting frame being made from 4"x4" posts and unistrut. Which is mounted on the hill behind the house. Posts will be postcreted in. Made a start on the frame. One half will be SW facing and the other half SSW facing.

That depends on your starting point. So old house, there are many areas that need attention first, before 3G makes any sense. New build, where airtightness, wall, floor and roof insulation are already taken care of (better than building standards) 3G can be beneficial as its impact is bigger, but it all depends on what you want achieve. Looking at u values alone, 1G has U value of around 5, double glazing latest spec about 1.4, 3G about 0.8. We have a lot of glass with 3G it represents about 45% of the total heat loss of the house. With 2G it would have represented about 66% on the coldest days. But on a strictly cost repay, maybe not sensible. Also it depends where in the country you live, far south have much shorter and milder heating seasons, than the North of Scotland for example. 3G reduces the noise transmission. We have 3G passivhaus certified roof lights from Roof Maker.

I bought my pipe from the farmers sales outlet place (where they sell tractors etc). 200m roll, I think, is the longest they do in blue pipe. I needed 100m, it was 1/3 the price of Wolseley plumbing merchant.

And there is another place they go for typical build pricing, which is way off, its good for planning stage, as it keeps council planning application cost down, but miles off for actual house building costs.

Not worth the court case if a panel was to be pulled of by the wind or "just" fell off, damaging something or someone. Use mechanical fixings. If you go this route use the correct filler material (mig welding wire) for corten, mild steel welding wire is not the correct material and will lead to premature failure of the welded area.

If you "need" to open windows to ventilate with MVHR there is something not right. My boost is 25% over the trickle vent rate, the MVHR has humidity sensors and very rare for it to auto boost. I will occasionally boost if doing a fry up or feel it needs after a long shower. To measure flow across those grilles you need to take velocity readings, say 10 across the grille and the average to numbers, the use the cross sectional area to get to flow rate. Or make a cardboard filler piece with a hole in center to close of the opening in the wall. Then you can use a normal flow meter to get the flow rate. Was that level of detail followed? With the grille how do you change the flow rate, do you have orifice plates at the manifold end?

But a sip on block and beam, looks nothing like the marmox drawing.

Just noticed the limited light available to the Au Pair room - not good

Sorry don't like at all. Exterior marmite. There is so much wasted space - let's make it huge. But lounge is just long and no depth, kitchen is way out of proportion is just too big. Top floor, just strange. Hope you don't need something out of the pantry when at a meal, everyone will be finished by the time you have got back.

Boost should be about 25% more than normal flow. Double the flow rate in the bedrooms is excessive. Doesn't look that well commissioned. Did the flow rates actually get setup with a flow meter?

I think you need to step back and look at what you are planning for the whole house ventilation wise. As once the fireplace is sealed up (assume the chimney will be ventilated from outside, not inside), your ventilation for the rest of the house will be compromised; as the open fire places are really your ventilation at the moment.

If you have open fire places you are going to getting high ventilation rates already. So I would just go with humidity controlled trickle vents. No electric usage, limited energy usage heating room. Humidity levels and CO2 levels are closely linked, so the only likely time for humidity to rise, is if you have a few people in room for a few hours and during the drying out phase after building. So - High humidity in extension, trickle vents open, small cross flow across room out of one of the chimneys. Humidity returns to normal vents close, cross flow stops. Cheap enough to install, passive activation, no electric required. Vents only when needed.

I've assumed as an extension and your are asking about dMVHR etc, your existing house doesn't have MVHR. Yes trickle vent - auto humidity controlled trickle vents, so should be closed most of the time. Replace one of the existing vent fans in a bathroom or toilet with dMEV fan, ideally in close proximity to the extension.

Other variables are How many bells and whistles you want Such as, home automation, flash lighting schemes, etc etc. Single storey or multi storey have different cost profiles. Your ASHP can cost upwards of £15k plus your heating system, so about £25k, or you can do it yourself for £4-5k for ASHP and full UFH. How much work you are doing or willing to do yourself or paying others to do. Are you project managing or going to someone for a turnkey house, or actually building yourself. Can you design the internal space or do you need someone to do it for you? How difficult is site is to work with, you may have huge amounts of material to get rid of, and it huge amounts of landscaping to do once you have built the house. Or neither on a small site.

I just used 70mm PIR around the whole perimeter of the house, including at the door thresholds. Which confused the tiler somewhat, as he never seen so much insulation apparently. You get close to linear metres per sheet at 300mm wide. Our slab is 25m long, without any expansion joints, and have had no issues so far, 2 heating seasons later. Did calculate the expected expansion and it was super small, but generally floor is only varies between about 19-20 when cooling and 22-24 during heating.

You do need access to the installer password, I just went direct to the manufacturer, they were good and gave them to me, I just said I was installing and needed the code. Had to find the installer manual online, to get all the codes for different parameters, in total 18 different parameters needed some input. Most were basic, like setting up DHW from a switched thermostat instead of PT100 probe, heating and cooling curves, enabling summer/winter switch. There were only two real running parameters to change. They were the fine tuning of the behaviour of when the heating/cooling cycles stops and starts up again. Out heat pump ran for 20 minutes, then stopped and basically say idle for about 4 hours. So for anyone interested this is what happens. You have a demand flow temperature let's say 26 degs. Heat pump will slowly bring the flow temperature up to 26 and try to hold it there, once the demand temp has been exceeded by "X" degs the heat cycle will stop. My original setting was 0.1 degs, so at 26.1 degs the heating cycle stops - I bumped that up to 0.5 to give a longer run time. Once the heat cycle has stopped the heat pump will resume heating when the return temp has dropped to flow temp, less target delta T, less a value "X", this being set at 2.5 from the factory. So return temp required to drop to 26-4-2.5=19.5. my lowest return temp was alway higher than this so I reduced the "X" parameter and ended up at 1.6 instead of 2.5. As we have seen many times the installer doesn't put in much work in to the controller side, does the most basic so he can walk away. In my case he would not changed the the settings mentioned above, he would have set the flow temp to 35 instead of 26 and left cooling switched off. Just had a look at my electric input over the last 23 days and my average is 6kWh per day. This includes 9 hrs slab cooling (4 to 6kW removal rate) (190+m2) and DHW heating to 2 people each day, electric mostly from PV.

2 x 4x2?

And if your not careful with the design you could still have a cold bridge. Do you have a drawing you can post of the current design?

Room sealed, means it doesn't take combustion air from the room, instead all combustion air comes in via the outer annulus of a concentric flue. It doesn't need to be in a sealed room, you could mount it on an outside wall if that suited you and it was frost free. However - The exit point of the flue through the wall does require sealing to prevent combustion products getting in to the house. Also what was the purpose of the air brick does this need to be replicated elsewhere?

Your return leg tee, placed close to the boiler rather than further away. So at loft level. Would be my view on it. Design by an UFH heating company? If your boiler min turndown is circa 1.5kW you could be fine, anything more than that you will have short cycling with one or two zones on and the rest off. You need about 50L of water engaged to allow 6kW of heat input not to end up short cycling for example.