PeterW

Yeh I moved (not even installed ..!!) some 1200 x 1200 for someone and they were a 2 man lift and when they installed them they used some sort of crane / sucker system as they were 60kg each.

Lose the sand - it’s pointless. Slab is also a mildly contentious issue with a few people too as it is a hang over from old build methods. With UFH do not lose the insulation or you’re just heating slab and ground below it. 100mm is bare minimum for UFH. With 55mm screed you’re in liquid screed territory anyway - how big is this space ..?? and do you really mean tiles that are 8 ft x 4ft..??!!

You need to read the requirements of L1B as that (assuming England/Wales) relates to conversions not new builds. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/697629/L1B_secure-1.pdf You will need to file plans showing how you’ve met the requirement - with your build the elemental method for uValues will be easier and more appropriate. In terms of lighting - just use LED fixtures everywhere as it is easier and simpler. Fire safety will be your other main concern with a conversion - check carefully how you build up the structure.

Ok that’s a UFH issue as the heat pump works for the hot water. Can you take a photo of the pipework leaving the outdoor unit and the manufacturers plate ..?

System boiler already has the controls for over pressure built in to it so you are always best having the buffer direct connected. Any reason for using the coils as most also are open volumes unless they are on ASHP and you’re trying to reduce the antifreeze volume.

Start by reading this ...!! And they move the heat exchanger unit into the house so can be noisy. OK so you need to protect it somehow as you need to use UV stable external insulation and also need to stop the local wildlife picking at it. What size are you looking at ..?? You can get vertical fan units that are smaller than their standard equivalent as they pack more fins into the box - the air/fan coil is the issue with size.

Welcome to improving a SAP score ..!! We have a new development with them near us and two of the houses have them on NW facing roof slopes so they will generate naff all but help the house get a “better” SAP score...! Agree about installing - the US did something similar with their 1m solar roofs initiative, but the cost in the UK far outweighs any benefit. A single panel will generate about 250kWh annually in a perfect installation so around £40 of peak electric - at current rates that will be around 7.5 years to pay back just its install costs.

@Dcc does the heat pump provide the domestic hot water ..?? You said this is getting to 50°C so it indicates an issue with the UFH manifold not the ASHP. Unless this is split system, there would be no need to take the gas out unless it was leaking. Is this all outside the house - there is no internal unit..??

Should say costings not coatings although I can’t see how much you’ve got in for that ..! Insulation and that sort of thing will chew £40/m so that could be £7-8k. Your issue with piling isn’t that you “only” need 30 sqm, it’s you need piles to stop the building rotating about its middle wall. You’ve got to basically load the cantilever to keep it from rotating and you’re going to need a huge spine wall to do it. That point load will need a lot support and you’ll need to ensure the building is balanced. All the steels will need to be very big too, wouldn’t surprise me if the structural cost was £60-80k on top of a £50k foundation cost. Then add in the walls, insulation and that could cost you another £30k with scaffold and access etc. @Gus Potter whats your thoughts ..? Feasible ..?

Split system ..?? That changes the whole game ..!! That needs refrigerant pipework so you need a duct not water pipework. Ideally it’s an open duct so you can drop the insulated runs in (can’t just bury them). The engineer will have to install insulated copper refrigerant lines and they need to be installed carefully and you can’t pull them in easily so it’s going to be expensive. And these units can be noisy internally. Any reason for choosing a split ..??

I reckon your costings are about 100% out ... sounds harsh but you have a difficult site and finishing this for less than £1500/m is going to be a really tall order. Piles and steelwork are going to be easily double - what about services such as drainage and water ..?

Yep pretty much. Long time to get heat as pumps don’t run that fast and the larger the pipe the lower the flow. Would suggest a buffer tank in the house too.

No as the ASHP would throw an error with gas over pressure.

Are they all gold plated ..??!!! That’s eye watering prices ..!! I would be getting them back as that definitely is not working correctly.

That points to the blending valve being at fault. Heat pump is getting to temperature. What did they replace when you say mixing valve ..? I’ve seen them installed upside down before ...!

Ok but a Cat scanner can be 900-1500mm off line - how wide a piece are you trying to claim...?

Would need to be 28 or even 32mm pipework and very well insulated. You’re probably talking 40-50 litres of water just in the pipework, it will take a fair while to get decent heat through to the house and cost a fair amount in insulated pipework.

Nope. Max output on a panel is 300W at peak, with losses it’s probably 85% output so 270W or with an inverter a little over 1A. Even a 5kW heat pump will draw 1.5kW so 6A min so it would be permanently drawing from the grid.

Cat Scanner then. Mark the ground above and then dig to prove it.

Mouse on a set of rods and a Cat scanner. Horizontal accuracy can be a little suspect at depth but how wide is this land we are talking ..??

Is this in a kitchen ..? If so, and you have no plan in the future to move the layout then it doesn’t go under the units. It can be simpler to just lay it everywhere and some suppliers do that as a matter of course. Is this supply and fit or supply only ..??

They all leak power - some worse than others. They also state they need minimum load when switch on which could cause you issues running the transformer without load.

Welcome..!! Wet Wales or Sunny Scotland ..?? Lots of knowledge on here of old buildings and the problems you’re experiencing so ask away.

12/24v is classed as SELV so is allowable in any zone. You can switch the DC side but beware your transformers will be always on and may not like it.

Yes - Osmo Top Oil. Brilliant stuff