Nickfromwales

Install the gas for now, and leave it all set up ready in anticipation of the fitting of an ASHP later down the road if the numbers make more sense then. If it's not a massive property you could get away with a decent high-flow combi boiler at £1500-£1800 plus fitting. Do you have rads or UFH? Most other M&E's I've spoken with still advocate using gas if it is available.... Your conscience is your's to deal with and your's alone. Also your money is your's to spend, and not others who may aspire to better things ( when it's not at their expense ). Do what is right for your budget and expected living costs, and if it becomes viable later, you or a new owner could retro fit the ASHP with ease.

You may be better off fitting smart TRV's to the rads and leaving one strategic radiator as bypass ( a towel warmer / bathroom rad possibly ). Short cycling wont kill the boiler, but it may reduce longevity. Which boiler do you have - make / model / kW? Maybe a good exercise would be to put the kitchen UFH on on its own and just sit at the boiler for a half hour or so to see just how many heat on / off cycles it does. Wait until the heating is up to temp before doing this check, as it'll be under duress whilst achieving the required heat output, which won't cause much short-cycling as that is heat thirsty, but then it'll need very little to keep it there once stabilised which is when short-cycling is likely to be at its worst. Short-cycling is caused when the boiler produces more heat ( at its lowest output ) than the heat load can absorb and dissipate into the dwelling. This is worse with UFH as the thermostatic blending valve on the UFH manifold will also refuse any temps over the set value. Typically 30oC-34oC and the boiler heat dial would have to be set a lot higher a the rads would never get warm enough if the boiler was set to match the UFH only. This is why people sometimes end up fitting small buffer tanks between boilers and UFH, particularly if rads are involved ( eg two different types of emitters each requiring two different temps, sometimes at the same time, and from the same heat source ).

I think the rads are coming on as a byproduct of the UFH calling the heat, as there’s appears to be no way that this is set up to arrest the flow of heated water to them ( if there’s no ZV fitted ). When rads are deselected, a ZV should shut to isolate the rads so the UFH is the only place heated water gets to. As I’ve said, this would promote short cycling so maybe this was set up ( albeit inadvertently ) to use the rads as a bypass when the UFH cannot dissipate the heat output of the boiler on its lowest output.

Yup, likely the rads, possibly another UFH manifold. There should be at least one ZV at the boiler to allow just the UFH to run, bu this may have been deemed a correct installation to allow the rads to run simultaneously if to stave off short cycling when the UFH load is minimal.

Do all the UFH loops get fed from that one manifold?

Hi. Looks like no 2-port zone valves have been employed to split the heating zones apart. Do you have any of these types of valves anywhere?

Leave all the fillers out and just foam / bond EPS insulation to the high points. That'll allow air to shift behind the insulation and keep condensation in the middle from being so problematic. Buy some sticky neoprene 50mm x 3mm insulation 'tape' and do the 3 sides visible of that 40?mm box steel, as that'll be your biggest cold bridge from outside to in, doubling up on the very inside face(s) only. Foam all of the corners and make it draught-proof as best as you can, but still maintaining clear open ends for the sheet profiles. Them being mounted horizontally makes this airflow a bit less 'natural', but shouldn't be a problem. Use foam / other suitable bonding agent and hold the sheets of EPS in place with 8x4's and some temporary battens, like shuttering. Try not to let what you store touch the outside walls and that will promote better mould prevention, but ironically you'll probably need to have some ventilation there in the summer to stop it sweating. Have you insulated under the floor yet? If not, you'll need to address the junction where the walls meet the floor as that'll be the biggest problem area if left unaddressed. Foam will be your friend here, just choose low expansion grade and minimise the wastage / nuisance contamination from over expansion. I don't really see the point in going to the expense of PIR tbh. EPS is pennies by comparison,.

As per my PM, I think sistered 5x2 C24 glued and construction-screwed to the existing will be crazy strong. You could even add perpendicular timbers behind the uprights like strong backs.

You don’t use the FB’s throughout! One steel across the garage door opening, one FB mid span, parallel to the steel, a wall plate on the back wall, and then timbers stitched in between. Looking at the pic, why not just use steel to form a T and then span from centre out? However......... As we are in fear of over-engineering this ( ? ) why not revert to the earlier suggestion of a 5x2 each side of the bottom of the trusses? So bloody simple, and if you’re going to board out and form I deck you there, glued and screwed, it’ll be rock solid. Every time I do structural joinery I look at it and think to myself “that’s way over the top”, but get an SE involved and that’s what usually happens ( as they have to professionally underwrite that solution ) so do you really need this degree of technicality for this project ?

What centres, what?

I did 6.1m with SE sign off for an attic conversion, and that was with the flitch, and that was taking the head of the stairs as well. Done in 7x2, sistered, plus steel fillet, drilled and bolted every 400 IIRC. Stronger than a strong thing, like near zero deflection, and the first time I'd heard of them too. Then used the same principal to reduce the profile of the huge 12" purlins down to 5" flitch. HELL of a lot easier to get up 3 stories vs steels, which would have had to have been done in sections, plated, and bolted up. Hired a Mag drill for the day, and it made drilling a breeze. 3 man job at that length as that steel will twist, flip and fly out of your hands quick-as, and good luck trying to stop it in mid-air.

Vertical drops are near inaudible, but changes in direction do cause noise. You can mitigate against the high frequency sound by wrapping the nuisance parts in sound deadening mat ( dynamat ), the bituminous stuff you see in car panels and under the kitchen sink. eg. That and as much acoustic rockwool batt as you can stuff in there. I wouldn't try for the utility as that's a long way with not much of a fall, especially if it's Pozi-joists?

If the fuseboard was relocated, is it now further than 3m away from the meter? What's the supply fuse rating?

Dead man walking..... What I would recommend is a small tiled boxing in between the existing boxing-in and the bottom of, say, a semi pedestal that had been, perhaps, bastardised by an angle grinder ( if that's what it took to keep the boss happy....... ). We all salute you!!

Ok, so when do we move from ‘gentle nudge’ to screaming “that will look crap”? +1. But would need to have a cavity at the back so you can leave pipes in situ and cut out for that boxing -in. Beware ones which are flush to the back wall.

Beauty is in the eye of the beholder....

With one hand on the angle grinder, ( fitted with a continuous rim diamond edge blade rated for porcelain ), and the other hand on your balls. Disclaimer : Holding balls is optional, but best to have both hands on the grinder. Slow and steady will do it, expect the porcelain not to like being cut.

Then deffo do not go for the semi-pedestal . IMO it'll look daft having pipes disappear into it after them being exposed below. I have cut a LOT of porcelain stuff in my time, to do things like this, but it's very unnerving and some stuff didn't live to tell the tale ?

Usually OSB3 these days for that?

I believe its because the monoblocks have a far less convoluted initial start up and run time so the split units tend to fire up 'for a good reason'. From the various suppliers and installers I've spoken to, the split units have to be justified for that choice of 'weapon' to be warranted. That's what I've picked up on from having many of these types of conversations over the years anyway. As always, anyone considering such an install should do their own due diligence and make sure the chosen equipment is fit for their particular instance rather than take generalised information from anywhere else. My experiences of this type of unit go back 2 years, and I see HP's have come on quite a bit in that period.

Buffers can be strategically positioned also, so you could get the much loved 'airing cupboard' to maximise on the 'waste' heat.

That's my understanding, yes. Not really as the buffer would only be inline with space heating and not the DHW, so adventitious heat given off by that vs nuisance heat. Very difficult to offer more to that post as we do not have client / dwelling specific parameters to hand.

Telford offer that with a lifetime warranty, and its 100% stainless. But yes, it was installed to be removed and replaced with spanners and a cordless drill in half a day or less.

Does it 'max out' when reheating the cylinder Dave? Whats the noise level in DHW mode is my point, with 5kw vs 300L?

Split units are a totally different beast to a monoblock, so everyone should keep that in mind and take that with a pinch .... Does show that the MCS scheme is good for that type of instance, but hard to understand how that ever became a problem because being an accredited MCS installer ordains you to do due diligence, way before executing the installation. Perhaps that particular install is simply missing a buffer tank.