JohnMo

Ours is similar, only once battery is fully charged and the PV has no where to go but export, does the CT clamp pick up and divert to immersion.

Thermal inertia prevents this. A passivhaus or one close to it doesn't change temperature quickly, also we are talking specifically about UFH not radiators. UFH systems are ultimately a huge buffer of heat store. The only way to prevent temperature overshoot by a simple anyone can use, low hysterisis thermostat. A normal thermostat will give an undershoot (in our house) of 3 degs and the same overshot. So a 6 Deg swing in room temperature. The 0.1 hysterisis is closer to 0.3 swing in 24 hrs, with heat pump running cycles and long off cycle. Through practical experiments I and many other have proven this works. Cooling I use the same thermostat set to cooling mode, mine is in the hall, but every house is different. You get temperatures in different rooms through balancing the UFH. UFH cooling isn't the same as Aircon, which cools the air. Underfloor cooling,room air temperature stays warm, but the room feels cool because the floor is sucking the heat from you. It doesn't have to, I paid £1300 for mine. The rest you are talking extremes, that makes no sense. The fact is you can set the target flow to any temperature you want, the heat pump would struggle to get there due to the floors thermal inertia. The heat pump sets it's actual flow temp based on return temperature first, to manage dT. Once dT has started to reduce it adds to the flow temperature... I have done the maths and the experiments. The facts are Anyway you heat the floor, the floor settles to approx 1 to 3 degs warmer than the room air, depending on the house heat loss (delta between inside and outside). Otherwise you overheat the house. The closer the room temperature is to floor temp, the less heat that is given off to the room. So if the floor is at 23 the room cannot get any hotter without an additional heat source. You set flow temp via calculation and experiment (combination of flow rate and mean flow temp).

Nearly all Scottish builds are dry lined (not skimmed). Joiners do the plasterboarding, and generally make a good job of it. I have lived one new build that was skimmed and all can remember is the huge amount of cracks after a few months. This house we are in now, was dry lined, nearly all our walls are over 3m tall and all ceiling vaulted so lots more joints than a normal house. Good job has little or no issue with finish. Dust - anyone doing it properly, will use a sander that has a hoover attached with HEPA filters to limit dust. But as with most things, do what is normal in your area. It's no use saying dry line and you can't find a decent dry lining company. Same with skimming. Get that sorted first as you line the walls differently with either taper edged or straight edged plasterboard.

You know there is only one way to answer that on an open forum, so why ask?

I didn't post it direct just in reply to another post. Been looking and I didn't photograph anything either.

Thought you building a passivhaus or close too. Sounds like you are being quoted for a ventilated shed.

What heat pump are they buying that costs £10k for a new build? And yes it is normal for any trades people not to pass vat to yourself. We had materials way in excess of £10k plus vat. If you are paying stupid prices like that get it MCS certified and let them claim £7500 back from the government. No idea what they do about vat returns don't really care. They aren't allowed to pass on vat to yourself under vat rules.

Don't see any issues our shower is twice that distance away. 8m and a rise of about 3m isn't much. That seems odd, was he a plumber or a random person off the street?

Don't need MCS for anything solar. Unless specifically asked by a supplier, keep quiet. It may get complicated otherwise.

Front of shed. Rectangular box is where pipes exit shed to go underground, the come back up by the cream watering can.

1. Sounds ok 2.yes and yes 3. I built my own insulated pipe, 110mm flexible hose, 28mm Hep2O and 25mm wall thickness black closed cell foam, had loads of aluminium tape, so taped over the insulation before inserting into flex duct. The ends of the Flexi duct I used stainless steel mesh foamed in place to stop rodents etc. About a 1/10th the price of bought stuff and does just a good a job. I placed mine ASHP behind a shed (insulated) and log store, so ran some of the distance in the shed, and the power supply etc were all housed in there. Near constant flow of air through the log shed help get the wood super dry. Back of shed

Really not even sure you need to use weather compensation on a passivhaus build, ours isn't and it just added no value running wise. Also found that even though the heat pump can deliver 25 degs, you actually have to run 28 to 29 as the floor doesn't cool enough to allow the hp to restart after a heat cycle. Two options 1 Batch charge floor on time of use tariff, set flow target about 30 to 35. 2 Run with a low hysterisis thermostat (0.1 Deg) such as Computherm Q20RF as a single zone flow at 28, the low hysterisis will stop overshoot and undershoot. Both I would do on a fixed flow temp, or a slight WC starting at +3 Deg add 3 degs to -3 to compensate for defrosting. Simple is best. I started with 7 zones, now have 1 Had a buffer - now I don't Had a mixer and pump - now I don't

As mentioned above materials installation etc by a trade company are zero rated for vat. You get the bill just the same as anyone would, but everything is zero rated vat. Same is true for labour only. Material only you pay vat and claim back. On our build I did all the plumbing except gas boiler, which I supplied, plumber came and was a time for labour only bill. They had no responsibility except gas safe compliance and initially commissioning boiler. If you want the plumber to 'design' and install, you really need to let them also supply also, then it's their fault if things are not as expected, any other way it's your fault because the stuff you supplied was wrong... Or design yourself and supply and the plumber is just a pair of hands doing labour.

If you store at Heat pump temps (48 deg) your standing losses are extremely low. Your boiler efficiency improves with lower return temperatures, actually heating the water up 5 degs will drop boiler efficiency so be careful on that side of things. The UVC cylinder will require all the G3 bells and whistles, as the volume in the cylinder is a trapped volume, so will be pressurized to incoming water pressure. Because you are feeding to an additional heat source doesn't change anything, with respect the design premise of the cylinder. I would use the cylinder as a normal UVC and let it supply your DHW only, set your boiler as priory demand hot water via the central side. To keep things simple just up the central heating flow temp a few degs at a time until you get the cylinder up to 47/48 degs. If you feel you have excess PV during winter pass the return water though a simple Willis heater. Why, 1. central heating not on in the summer when you have lots of excess PV so everything excess can go in to DHW 2. Preheat to return leg of the boiler will drop boiler efficiency throughout whole heating season, when not much excess PV is available. If you do have plenty of the PV in winter excess, use a simple Willis heater. 3. Even upping the central heating flow temp to allow DHW heating with keep boiler inside condensing mode. 4. You need to do G3 regs so do it for proper DHW. 5. Preheat water requires additional diverting valves to stop boiler firing every time any hot water tap is opened. 6. UVC cylinders are way better than combi for water delivery time and flow rates 6. Its simple

No sure how your attachment is done, but it does not open.

Not sure how it sets flow temp or if it can? Optimised start and stop is available on a several thermostats (Salus SQ an WQ series for example)g, so not really seeing any advantages over a £60 thermostat. It saves x% is meaningless rubbish in rubbish out, with facts to back it up. Weather comp or batch charge on time of use tariff, for good running costs

Tell him to as per drawing nothing else, if he has to redo at his own expense, that's his issue - he should have read the drawing. 2 layer of 100 and 50mm on top is ok. But do vcl it as per drawing.

What do your drawings specify? - he should be building to the drawing not make it up as he goes along.

Or fan coils, more expensive but you never have to run above 35 degs and you only need them in the main living spaces, design bedrooms for 19 degs not 21 and a smaller radiator will do.

They may not be more energy efficient as far as frames are concerned, so make sure you know what you are actually buying. A good frame with a good double glazing unit will be Uw 1.2 the same glazing unit in a bad frame could be Uw 2.0. They will quite two figures Ug and Uw the g just covers the glazing - W covers the whole window heat loss. We renovated an old house in a conservation area and we were not allowed to install uPVC. So check before you buy.

So you got a G4 then.

Basically you need a new EPC or SAP report when you first build or then go on to alter the fabric of the building. Nothing is blindingly obvious. A lot of SAP reports can be shite in, shite out, so make sure they use the correct assumptions i.e. check. Not sure what you mean by a '4' as EPC ratings are A to E?

I hope it doesn't burn in my Durisol blocks also, surrounded in concrete and woodcrete (which doesn't burn)

Cooling may not be very effective with radiators as the water just stays at the bottom of the radiator. A thermostat when in heating or cooling mode just switched it's own logic for call for heat. You need a setting change in the heat pump to make it cool. I would reset to your original settings, those settings are for heating, I suspect the 25 degs is min flow temp. When in cooling mode the parameters change to ones suitable for cooling. Some heat pumps are sold without cooling as standard, but all can do it, some need additional bits to make it work. Mine needs a zero volt switch to move it from heating to cooling.

I did a 50mm service void, so just a big standard one for plasterboard.