JohnMo

You may be able to polish it back, but be prepared to end up with a thousand pieces, if you go to fast or get unlucky. You will need a diamond coated disc. But if they got the measurements wrong take it back. If you got them wrong...

You heat pump will have an air release valve within the monobloc. It will also have a air purge cycle, where it runs the circulation pump in a pattern aimed to move and release air. If you have a buffer you really should have a bottle air trap at the top of that. So fill the loop with water and initiate the purge cycle - you will need to read the manual on how to do that. Then let it pump to the buffer and back. Cycle will be 10 to 20 mins The high point in the system should have an air trap as well.

Is this a wood burning stove? If so get the people in that sweep your flue or service your stove to repair it.

similar price to PIR.

I was previously talking about the combined AC coupled inverter battery from Sunsynk, that was G98 approved. I suggest 3x units. They are G98 approved and the only possible options are to allow export or not allow export at all. @Dillsue said that wasn't possible to couple several units together and retain G98 certification, which I am not convinced is correct. The bigger G99/G100 hybrid inverters, you can set any export limits you want. But @Dillsue is concerned your kids or his kids will mess with settings and you will shutdown the local grid. Not sure about that either.

No I don't or didn't, but why would you be exempt? You could the person making the most noise!

Why would you let your kids f*CK about with stuff like this? But with the Sunsynk inverter you can set export limits, it's either allowed to export or it's not, there are no settings for 1kW or 10kW, just the default G98 setting

Why? The units I spoke about are only parallel at the battery, so no different to adding more battery capacity, that all DC. The other connection is a CAN connection. The unit already has an inverter larger than 3.6kW, but is still certified as G98. With a master inverter you only have one inverter controlling stuff.

We have 13kWh, with a 6kW inverter, all electric house, with ASHP (6kW). Last year we were on E7 tariff and for about 300+ days the battery got us through the day (charged on low tariff plus PV) the other days we imported peak electricity for some of the day. Now on Cosy (3x cheap periods) and expect to get closer to 365 days per year on battery without peak rate import. Some other things to throw into the mix Most hybrid inverter in a power cut will only power a couple of dedicated UPS circuits, not the whole house. AC coupled battery inverter will continue to run whole house without interruption (make model specific - GivEnergy AIO does for example). Inverter size matters, to small and you import peak tariff rates. For example 3.6kW inverter, if draw is above 3.6kW that excess comes from the grid directly. So need to understand functionality that is important you. PV yield by month (summer stupid high, winter stupid low). Loads of PV may not make sense if your inverter just limits generation 6 months if the year. Do you have power cuts, if no no benefit having something that powers whole house.

Playing devil's advocate, not saying this is right or wrong - if you can set export to zero, such as all Sunsynk inverters, do you need to tell anyone anything? You aren't influencing the grid your system is off grid for exports, only importing to charge battery.

You pay a fee for the to due diligence on your install. You have to pass on documents about the electrical install and anything structural to prove it's fit for purpose. Once that bit through the register you export. So way cheaper than paying an installer the MCS tax. Octopus are the only company I could find that does this.

Better comfort compared to running radiators at 70 yes, but doing lower flow temp radiators, no should pretty similar. Damage risk huge, payback your grand kids may see some.

Not exactly sure, but you cannot have a G98 approved inverter that does G100 management - can you? If it's G98, it's G98, not something else as well. Otherwise it's a G99/G100?

I thought that for a long time, after doing a self installation. But in the ended paid out £250 to octopus to get paid for export. No off set my bills with export payments. You will be surprised by how much slips to the grid even with active management to prevent it.

Just takes about a hundred times longer to form. Our last house 1830 still had original roof - zero moss. House before that moss starting to form after 2 to 3 years - concrete tiles.

Another option is Sunsynk LifeLynk X - 3.6kW hybrid inverter, 3.6kWh LiFePO4 battery & 4.5kW MPPT - SM3.6KWLL - G98 Approved These are AC coupled inverter battery with PV input. The can be run in parallel configuration with one acting as master and others as slaves. So you can run any number of these and should keep the G98 certification. Each inverter battery will take 4500W PV input. So for around £3k (+VAT) you get 10.8kWh battery storage and more than enough inverter capacity for you PV etc.

Is this for two properties? As you seem to have two plans that are different?

SunSynk 3.6kW AC ECCO, has a 7000W MPPT and a rated AC output of 3.68kW and is G98 approved. So no need to tick the G100 box, you have the G98 box ticked instead. Solar Input - 3.6kW Ecco Hybrid Inverter Max power input – 7000W Max DC input – 500V Max current input - 2 x 13A MPPTS - 2 MPPT range - 150~425V

G98 is a notification, you do after the event, you are just telling them it has happened. There is zero option for them to say no.

Here are some numbers comparing PIR and 0.032 mineral wool. Ca vity insulation Underdraw (PIR) Rafter spacing (mm) U-value (W/m²K) A 150 mm PIR + 10 mm foam infill 50 mm 400 0.113 A 150 mm PIR + 10 mm foam infill 50 mm 600 0.110 B 150 mm mineral wool 60 mm 400 0.144 B 150 mm mineral wool 60 mm 600 0.136 B 150 mm mineral wool 70 mm 400 0.134 B 150 mm mineral wool 70 mm 600 0.128

Not really always correct - Frametherm 32 has an R value of 0.032 and PIR 0.022W/mK so 50% difference not 100%. There is no shrinking with mineral wool, and you are not bridging with a lower R value expanding foam.

Just use a heat pump cylinder 400L you easy get a 4-5m² coil in. Even a 3m² would give quick recovery. And possibly stay in condensing mode for most the reheat if you set it up well. But if you have room for 400L cylinder 2x 210L slimline heat pump cylinders would give way more flexibility and faster reheats and you would get 6m² coil out the box.

I would just do mineral wool something Rockwool Flexi or Frametherm 32. Then under-draw in 60-70mm PIR. Easier life, as good U value on paper and likely quite a bit better in real life. Better decrimant delay.

Slates. A copper strip on the ridge..

Sort of Use the heat-loss formula: Q=U×A×ΔT where U = floor U-value (W/m²·K) to the underside/cavity, A = floor area (m²), ΔT = temperature difference between the warm floor (mean UFH floor temperature) and the space below/crawlspace/ground (K). So you need to use your average UFH flow and return temperature. Average winter temp is around 7 degs (void space temp), air is a good insulator if in a closed box, but your void will be ventilated, so not good. Best case U value will be building regs, it can be worse and compensated in other areas. But we will use 0.25. Flow temp likely to be mid 30s so 35 flow and 30 return so 32.5 mean. 0.25x100x(32.5-7), so 640W. 640 x 24 x 220, so about 3400kWh At 8p that's £270. If your flow temp is higher your losses get higher. If you can flow lower well done but I doubt it. The above is based on average temp, so milder days less losses, design day losses double. So on a -3 day your downward losses alone will cost £2.30.