Nickfromwales

Are you sure it's dead? I often fall asleep in the bath .

The red and black taps at the top are off. The black thing is prob a filter. The black taps on the filling loop are both fully open, not good. Close them both and get the pressure down by bleeding a radiator into a bucket. Whsts the make / model? A quick read of the MI's will say if there's a removable internal link to connect a timer to or whether it's maybe got it already onboard .

To boost the uvc . Thats a good figure for your CoP !

I think the unit would spend too much time idling, and 'stuck' in limbo trying to satisfy DHW without freezing and the space heating would get neglected for excessively long periods of time. I know you have a buffer so that may make it feasible if it stores enough energy to bridge these periods where the house would go 'unsatisfied'. CoP has to be maximised by design, from the outset, so you really should know what to expect before even plugging it in

Vaillant do a complex setup as I describe above, basically it allows an uvc to be heated at high flow temp whilst the heating is separated from the S plan and is then blended down to suit the required ( reduced ) flow temp for the times that the two are running simultaneously. Afaic just fitting a W-plan ( DHW priority ) arrangement would do that with ease. ?

I'm unsure how you achevied that as oil boilers don't modulate ? Did you use digitally controlled electromechanical blenders off the store? I know Vaillant do such a thing but it was off the chart complicated from an end consumers POV and wouldn't control two different temp zones ( a mix of high temp rads and UFH ) so I didn't pursue that any further.

I tried to get the all-singing-all-dancing Vaillant W-Comp control to work and it was so uneconomical on time and effort by the the time I'd have actually got it fine tuned, the transmitter in EXACTLY the right position outside and blah blah blah it would have soaked up about 2 years worth of savings getting it to work properly. Single increment changes on the hub saw either too hot or too cold flow temp fluctuations and in the end even Vaillant admitted I was pissing in the wind. I have no experience of other manufacturers W-Comp controllers so maybe someone could give feedback from a real life case study of a PROVEN setup that works accordingly?

It looks like plywood, capped at the front with a pine nose to me.

Get comfy, there's a lot of info here. .

Keep up the good work ?

As Jeremy would say, "the laws of physics won't be changing any time soon"

How long do you intend to be in the property?

Plus if you stick with LPG then no need to pay towards the radiator alterations. Work out what that would have cost and see how much gas that would pay for .

I'd find new heating installers as theyre causing you unnecessary worry and should have asked different questions like • what spacings • what pipe • DO they fit any valves etc and what type ....instead of just assuming the worst . Theyre just being dicks, so stick with MBC and watch how guys who do this daily get things done. . As abve, you choose the above ground stuff, and MBC are going to use pex so let them carry on. ?

Youll be fine with what you have there tbh, with the additional cross bracing. The one I did had the ply for a few reasons, one was to act as a noggin as the TF company had decided they aren't necessary ? Your arrangement is much like another I did with the same tray. 15 lengths of 3x2 iirc

The ply is belt n braces but I'd never even consider doing it without it tbh. Are you saying you need to offer the ply up from underneath in sections ?

Yup, but at least they'll always have a tank FULL of hot water .

It's down to how good the subfloor is tbh. I always set them into a lattice of Sikaflex EBT and drill and countersink every single hole position. A solid deck of 18mm plywood D4 expanding wood glue ready for fitting the 9mm fillet of ply used to raise the tray accordingly, The tray set into SF and screwed at every hole marker ( the little pillars seen in the GRP from underneath ). See the little circles in the pic above You don't need mastic on the ring TBH ( DONT USE SILICONE WITH GRP EVER ) but I do use EBT regardless as I know it's bombproof then. The reason that Impey don't show that is because they assume you'll be covering the whole thing with they're waterproof decoupling membrane which terminates into the mouth of the waste, therefore after / past that ring and below the surface of the tray, negating the requirement of any sealant anywhere as the water ( in theory ) cannot ever get there anyway. Problems arise if you stray away from the Impey family of products so are you using their membrane?

Why not just use some stickyback trunking ? Lid just pops off for future tweaks and will look a lot neater for a few £

It's unique so difficult to say exactly how to plumb it. . Do you have detailed house plans showing DHW tank location and bathrooms / kitchen / utility ? If you upload those here I can advise better, apologies if they're already up elsewhere.

Yup. I always kango them out after drilling a series of holes to reduce breakout. Damp brick / brickwork is a real pita when dry diamond core drilling .

Sorry I'm late @PeterW you get the blue peter badge, but no cigar for not spotting the other side effect here The non return is indeed needed where it is, but for the wrong reason, ( I'll explain below ). Add another, where the green arrow is and your problems will end. The pump ideally wants moving too as it shouldn't be pumping downwards TBH, but instead should be laying horizontal or vertical but travelling upwards to allow natural venting / removal of air. Not life or death but can add to the longevity of the pump. Insulate the pipework in the attic and have that hot return ( HR ) pump triggered by an occupancy switch like this in the bathrooms so it only runs briefly prior to when it's needed. It can be set to run off a timeclock too if easier but I'd certainly not make it redundant as it's there to help, by circulating the dead legs of hot water pipework to massively reduce waiting times at the outlets ( particularly the basin hot taps when washing hands after visiting the loo ). One observation is that the plumber has fed the HR into the very bottom of the tank whereas it should be going into a dedicated tapping midway up the cylinder. Does the cylinder have a blanked off tapping midway up somewhere around its circumference? Not all UVC's have one so that's maybe why it's like this. The problem / side effect here is that a system with a HR pump should only be able to draw hot / very warm water back up the return leg when the pump is off. In this situation the plumber hasn't mitigated against the fact that he's connected it where luke warm / cold water will reside, hence your system is currently able to simultaneously draw cool water and hot water into the hot pipework, hence your problem when the pump is off. Another is that in a house with all UFH this should really have been a thermal store. An hour or so after the heating comes on, go see how often the boiler is lighting and then going off whilst there is demand for heating. It's probably cycling quite a bit then and could benefit from a buffer. All depends if you want to open that can of worms or not as ignorance can be bliss ??.

Get £600 ready to lose ? Hire, hire, hire. Use, abuse return.

Any decent core ( diamond NOT Tct ) will have a clutch that any reasonably robust man can hold onto, I've used them all. Where depths are greater than the depth of the bit you need to go halfway in and then break the core out before carrying on. It's the dust / debris held between the core and the bit that cause it to snag. With a makita or dewalt dedicated diamond core drill I'll happily drill for a boiler flue up a ladder. Ask for a drill with an electronic clutch and you'll be fine. 50mm cores you can do in your sleep.

Manifold arrangements are very good in certain circumstances, but if there would be a long run of 25m then you may well do better with a couple of 22mm hot legs, reducing to 15mm for each outlet and have a hot return ( HR ) circuit teeing in at the point the 22 drops to 15mm. The downside with a manifold is that you can only realistically keep a HR loop between the tank and the manifold, whereas a regular but cleverer-erer arrangement will allow you to tee in the HR point much closer or even AT the outlet (s) worst affected. The manifold setup only really works if you don't need a HR where the runs, post manifold, are short enough to negate it, but you can also consider a HR if there is a manifold, ( but it's away from the hot tank ), as the additinal larger bore primary supply pipework and the water in the manifold will then be a huge dead leg. If I ever did my own build it would be a couple of hot manifolds suitably positioned away from the tank, kept hot by a HR loop with everything super insulted to reduce losses. I'd deffo go with a bit of pv to compensate, even if just a small DIY array to offset these and other incidental system losses.