Nickfromwales

Service battens affixed to every stud prob easiest. Maybe a sheet of 9mm OSB / ply cut into strips if you don't need to run cables down those walls? That's a proper PITA of a detail which the architect should have designed out IMO. 2x studs could have been sistered together for each rising strap, with the affected stud reduced by 6mm and its sister left flush for boarding. That's OK to do retrospectively tbh, so would be my favoured option here just to bring the wall forward to clear the straps and screws. Maybe consider horizontal 25x50mm battens at 400mm OC? A ball-ache any way you 'cut' it, as the shortest PB screw is 25mm.

Yes but you hadn't reduced the 4:1 figure which I would imagine is optimistic for heating via rads plus UFH, if keeping existing rads. 4 hours on Octopus? What will you do before that kicks in? If the system has already heated up via 'other' the HP will have very little to do, so deffo smaller HP going flat out imo. Noise for the neighbours may be a consideration, if you have any? Can you introduce a sizeable buffer tank? You could use those 4 hours to heat the system plus the volume of water in the buffer, then for the HP to shut off after the 4 hours expires. The heating would then consume the stored energy before needing to draw off oil again. If your home is very well insulated and has such low heat loss characteristics, then it sounds like this would ( could ) be a good option. Any HP will suffer short-cycling if the house performs very well and the heat demand is very low and steady ( eg after it has been initially brought up to 'comfort' temp ).

Do the hot feeds to the wash hand basins in 10mm. I do this on every job where running an HRC to an outlet is on the borderline of being overkill. Plenty of flow rate even with mains which are half of what you have there. Its just one more fitting each end, so an extra £10 per 'leg'. Chicken feed when you pay nearly £3 for a cup of coffee........

Pipeline Centre should carry stock. This is the best option here, but the OP would still have soldered joints to make at each end. @cwr, you could get a 6m length and have a commercial plumber form a mechanical bend at each end if this is really keeping you up at night. You seriously will be fine with a soldered joint. Any good plumber can solder this in their sleep.

Some manufacturers say the first 800mm - 1000mm in copper, in case the boiler overheats and sends super-high temp water out for a few seconds. Plastic pipe and fittings have very low pressure ratings at very high water temps.

Hepworth do a 6m length in a straight run. LINK People have been soldering pipes longer than they have been pushing fittings onto plastic pipes I've been plumbing for nearly 30 years, and I would use copper in this instance over plastic for sure.

So what is your rain screen going to be then?

A very rough check would be to run them at 40oC flow temp from the gas setup. If the house won't get up to temp, you're going to need bigger rads. You may also need larger bore pipework to get a higher volume of the 'cooler' water circulating around the system.

Get a glass of warm milk and have a bedtime read

Hi. Not garbage, but missing some key points to better calculate your comparison A CoP of 4:1 would be achievable if the flow temp to the heating emitters is very low, but with rads in the mix you'll likely be up much higher. When the temp goes up, the CoP goes down, and it goes down again when winter removes a significant amount of heat energy in the air. Lots of things change these numbers, such as the amount of insulation under the UFH, the fabric and ventilation heat loss of the house ( how many kWh of heat are required to be input to keep the house at 21oC when it's bitterly cold outside ) and more. The oil will be a difficult beast to replace, especially in a home which is not efficient and highly insulated / excellent glazing etc, so maybe consider going for a Grant Hybrid ASHP with an integral oil burner for the bitter parts of the year when the HP cannot quite keep up. LINK

Just solder the joint and move on with your life I've done thousands of soldered joints, water / gas etc and it's perfectly fine. You're waaaaayyyyy over-thinking this. Solder it up, pressure test it at mains for 24 hours, and get it in the ground.

Not magic, maths and sense.

Please don't, it's carp compared to Wavin Hepworth ( aka Hep2o ). 15mm for shower feeds, yes.

I’m not saying to over heat it, but without a decent amount of ‘thermal heat capacity’ you cannot store heat energy and slowly release it, as you do with your storage heaters. Getting the whole house and internal ambient materials / surfaces up to the desired temp then becomes an event, rather than a constant. Uneconomical by comparison eg between thin screed over a little bit of insulation vs passive raft.

PCM58 is called that for a reason . With an ASHP you can heat an UVC to 55oC, but the immersion heater can then push you way past that to 85oC for a huge increase in stored heat energy fir the same capacity device. SA wins on physical size, UVC wins on not being a single trick pony. SA fails by the sheer number of failed units I’ve had to exchange or repair vs UVC’s.

You’d still be using the ASHP for DHW, via an UVC, would you not? With such a thin screed there will be a very short “thermal time constant” so you’d be stuck with buying electricity on demand. Expensive option if you don’t have a passive raft / similar to invest cheap heat into and leave it leak into the property, as it’ll be 1:1. If you have other plans for DHW, you could still just buy a cheap ASHP for heating and get close to 1:4 or at least 1:3. With electricity prices rising, I’d not go direct with a thin screed tbh.

Watt hour were you up until?

Elementary, my dear kW’stson. The car can only charge at a certain rate of knots. To absorb sporadic pockets of excess solar PV the charger needs to be in ‘eco’ mode, and the car tethered whilst this is happening. A domestic battery is fixed, and is dedicated to absorbing these ‘opportunities’, and will be the simplest and best option if capturing solar PV revenue is the remit. Most people will be wanting to drive places during the hours of daylight…. 100% sound advice.

They don’t live with you The actual loads will be the vampire loads of a typical house. Stuff that you cannot be bothered to unplug, or switch off, or put into ‘power-saving’ mode. So a £3k system in my house would probably pay back its capital investment 3x over in its useful lifetime.

Praise be!!! Someone has finally said it. This haas been my advice to clients for a long time, even more so where the source of DHW is from PV or an ASHP.

Agreed, which is why I always tank / make bombproof every single bathroom job I do not like cement board, as it doesn’t comply to the uneven nature of stud walls etc. Last time I used it, to an architects spec, it was bonded with Sikaflex as well as screwed. Never had a bathroom fail, and I learned fast back in the day through insurance work. A good way of knowing what ‘not to do’ was to take note of what had been done ( which failed, sometimes catastrophically ) and not repeat it.

Gas nailed onto concrete, with clip rails.

Yes, yes it is. There’s a magical, almost mystical fountain of youth that it pours out from. The more In drink, then less old I feel., ”All hail the ale”.

Simple solution is 3x2 studs, the right way round, and double up at each stud with 2x 3x2’s glued and screwed together. Shallower footprint, more insulation, stronger than a 4x2. And deffo no need for noggins then.

Because they will all be tanked.