Conor

We've similar heat load in a 315m2 house and have a 9kW heat pump and does fine (even now, only on 7hours per day to keep the house at 18-19c). On paper a 5kW would do the job but tbh it would really have struggled in this cold weather. In your case a 5/6kW pump would do the job, if you hit the PH standards.

I can't remember, partner took care of it. All I remember is it cost twice as much as normal underlay! It might sound drastic, but you could look in to putting insulation in your celing void and doing some filling work where the joists enter the external wall. You might end up with a lot of ceilings to patch up and paint, but you'll reduce you heat loss and get more out of your UFH.

I think you've summed it up well, lots of heat going down in to the ceiling void and then going tho knows where. Was the carpet and underlay rated for UFH? We have that and heat transfer isn't an issue. MVHR won't make a difference, all extract air goes out the building through the heat exchanger and then fresh air in to the house... So the air tha is distributed is slightly cooler than the average temp of the extracted air. So want warm anything

I've has several dud no nonsense foam cans from B&Q/Screwfix in the past, some so under gassed that nothing comes out of the can. Returned for refund.

Were the joints sealed/taped? Is be surprised they would become disconnected. Possible blockage?

Our passive ish house is about 1c over 14 hours when it's hovering around 0c, so less than 0.1c. hard to really know tho as the UFH comes one every night regardless. I'll have to get some monitoring setup.

What are the details of both 5hw damp issues and the proposed solutions? If it's a below ground level wall and floor, then it needs external drainage and tanking. If this was never done then an internally applied system will not work unless the water has somewhere to go. Get three quotes from different suppliers, regardless.

What's below the vent at ground level? Paving, grass? You could just locally lower the ground level as you suggest, backfill with pebbles up to 150mm to reduce splashing. What's stopping you from doing this? It would only need to be 200mm or so wider than either side of the vent. Drainage needed tho or it'll fill with water to ground level during heavy rain. Photos?

I had a couple of those. Just used the 5" grinder with a fine blade and went round it. I'll have to touch up the paint on the ceiling tho!

We would get the same if the trickle vent is left open. Cold air falls in and causes condesation at the top of the frame. If it's closed, nothing, except a bit after a got shower. But a 10c ambient temperature hints at some serious heat loss / air infiltration.

Everything should have been zero rated. It's debatable whether the diversion works for the pipe can be zero rated. It would be classed as modification of existing infrastructure so not eligible. Tho from reading here over the years, seems people have had utility modification works zero rated.

I think this is a miswording. In theory you need planning permission for PV panels in a conservation if visible from the highway. We included ours in our application and wasn't an issue.

I got a full package from coolenergy, heatpump, buffer, 300l HWC, carel controller, glycol, the works. That was £6300 after vat reclaim. I then got a team of plumbers in to do the whole hoise, from memory they spent about three days between connecting up the heatpump, plumbing the cylinder, commissioning the UFH (connecting manifolds, installing pumps, valves etc). So that about £1600 and that included two days of the G3 guy. Then there was 28mm pipe, pumps, connectors, brassware etc. So another £300 ish. Then there was the spark for a day, he couldn't get it all done so brought his mate in fro another half day... No bill yet but reckon £300. That brings it in at £8500. Is the valiant unit a split or monoblock system? If it split that that brings in extra costs.

Stalker.

Plenty of choices on Screwfix. How far from the wall is the pipe? If there is a decent gap, you can fit a clip /munsen ring to a small piece of 12mm ply, slide in behind the pipe then screw in either side of the pipe. Had to do that on a few of my ventilation ducts after they were fitte and I realised they weren't supported enough. But with this one it should be easy enough to fit to the pipe insitu and screw directly to the wall.

Just don't dab, set a full board across the block wall and stud. Use hammer in fixings on the blocks.

Similar size and spec to our floor slab, ground works, drainaged, stoning etc were 4k... But that was a lot of digging... Shuttering and mesh laying was two guys for nearly a week. I think you'd be looking at £8-£10k.

Nope, not a good idea. Do you think your insurance will cover you if somebody gets electrocuted? And will look interesting on your site risk assessment 🤣 Getting services on to site is a ballache. Get started soon as possible. Approach your DNO and get a tempory supply put in to a kisok. Then you get them back to bring the remaining cable from the kiosk to your perm meter box. It'll cost a little more than a single application but it'll make life so much easier. Other option is to ask can you do without electric at all until you've walls up? Get water and sewer sorted as well, these can all take 6months +

Basic question... But is the pump facing the right direction? I.e. pumping the same direction the boiler pump is? If it's the opposite way round that would account for the abismal flow rates. Same for the valve. Reason I'm asking is that you'd normally have the flow on the top rail, and return on the bottom rail.

Developer build or self build? A lot of noise comes in from around frames, trickle vents, other little gaps. What's the general build quality like?

What construction / era is the front door? 90s first generation PVC? Solid timber?

Ah, didn't see the solid wall. Looks like there's no brick course on top of the door and side window? To install a proper roof, you'd want a lintel / course above the door to take the roof joists. A flat roof would work well here as you can reduce the fall to 1⁰. But you'll not get much insulation in it. Is this part of your heated envelope of the house or outside? Sounds like it's separated so any insulation a bonus, not a need. And I don't think you'd need building control either. I'd phone a couple local builders and see if they can come round and price up. It's a pretty straightforward job.

MVHR nothing to do with UFH or ASHP so don't be going to a single supplier. Is this a new build or renovation? Lots of factors to consider and it helps to have as much as possible detailed before speaking to different suppliers so you can better compare and contrast quotes.

You don't have the fall for a tiled roof, you'll have to go for a flat roof of some type. You'll likely need to build a new structure to take it - at the very min a couple steel posts and beam across on the glazed side. You'd replace the glazing while your at it. Gets expensive quickly if its done right! That's also probably why the existing roof is leaking water isn't clearing fast enough and it's getting through the joins.

Sounds like an easy case for DIY. You'll have a single, small unit, two manifolds and no more than 12 ducts in total. No reaon why you can't get the job done for less than £2k. Assuming no strange beams stopping direct routes and a central ish location for the unit