Nickfromwales

No cursing here, just frustrated for you. As you’re under the gun you’ll want the quickest route obvs. If it’s cold water going out of the tundish then it’s not cut and dry as to what the issue is. The control group (multiblock do-dah that one pipe of the tundish comes from) governs the cold mains pressure to the entire hot and cold system. IF, the water is defo cold then it can mean the cold mains pressure reducing valve has failed, so cold mains water is just being allowed out through the 6bar PRedV, sometimes this will happen sporadically with use of outlets temporarily relieving the issue or network pressure fluctuating. There are 2 places the system ‘blows off’ from, and that’s one. The other is the T&PRV (temp and pressure relief valve) that the other pipe to the tundish comes from, the one high up at the side of the cylinder, usually with a red cap. This operates if the cylinder pressure gets too high, or if the water gets way too hot; bottom line here is, if the hot water is on and the cylinder is hot then the water in the tundish will be the same temperature, eg not cold as you suggest. You’d likely see steam coming off it / out of the tundish if so. Questions are: 1) was the hot water heated or being heated when you say the cold water was detected at the tundish 2) are you sure it was cold? Do consider getting those Tesla valves bought and installed, may be useful to hit different Screwfix’s if one doesn’t have the qty you need in stock, and have these to hand for the chap to fit. Will save you time and money in the long term and they’re quite cheap. These make a proper service / inspection an absolute doddle, and diagnosing issues becomes much easier too, vs having to fully drain down and refill both heating and hot/cold systems every time there’s a need to check / top up the expansion vessels pre charge pressure or identify potential issues etc. Now it’s down to cost and time I guess, but as you’re a rental then I think it’s best to not roll the dice. My 2 cents is to get the 2x cold (white) expansion vessels changed, but to also increase the volume. It seems what you have is not sufficient for this to be long/term reliable, and you don’t want to keep pushing this fault along waiting for it to go again. May as well fix it properly, once. Either change these out for the next size up, or add a third 24L vessel to this setup is my advice. I imagine heating by immersion a lot through summer etc gets this tank super-hot routinely and takes it to its upper limits. Adding more volume is one solution. Setting the temps on the immersion a little lower is another. Eg if you have sufficient hot water during winter from the ASHP, when not heating from solar / immersion, then the temps could be dropped so the safety devices aren’t being pushed to their limit all summer. Without being there I cannot rule out a stray mixer tap back-pressurising the cylinder, but do you know if the cold mains (strictly) only comes in at the plant room and that goes to the control group on the UVC? If both points are so, then the whole house hot and cold supplies should be “balanced”; this is something you could ask the ‘engineer’ when they call out. It’s very easy to just change broken things without finding, or curing, the reason they broke. That’s my concern.

I was confused by this term too. However a robot in cyberspace says this: With MEP on board this should get sorted, assuming some element of heat recovery from ventilation if it’s a sizeable property. The only factor between pipes and heater wires is the functional longevity of the wires. As more info lands here, the more I think this will be a serious chunk of change going into a commercial heat / cool / ventilation setup. Your MEP people may suggest A2A AC as it’ll service both requirements (heating and cooling) and will introduce heat pumps to the situation which would seem sensible.

Nope. Direct electric is near 100% efficient. I did I’ve an external heat generator, then wet manifolds, plus ongoing maintenance, losses, and the I detect nature of heat delivery, you’re going to be worse off unless the cost per kwh is managed; so gas or heat pump.

They failed to do due diligence, just an assumed 2x dead EV’s at 5 years old. Sugar coat it if you wish. This is just shit service.

Clunking in an attic would be on timbers shared by most bedrooms

👆 @SimonD gets what I was looking to achieve.

Lots. So the most efficient way to heat this would (on the info I have so far) be to have the screed act like a radiator. Minimal mass, achieve heat quickly, turn off as soon as the premises is to be vacated. Heating up 150mm (plus another 30mm or more of adhesive and stone) of solid mass will take a long time, but will hold heat longer, just need to understand downward / outward heat losses better to say if this is a good idea or not. Absolutely a no brainer to run this off a heat pump, if this is anything like a long term situation. Convenience comes at cost, so the mention of using direct, on-demand grid electricity to do space heating is one where I also assume someone is happy to foot the energy bills per annum? At that stage I’d probably advise the use of in screed electric heater wires, as this is close to 100% efficient, less losses.

Ffs. I googled ‘model’ and ended up back here…..

This is lacking a lot of info. 150mm composite what? Purpose of building and anticipated w/m2 heating needed, and what’s heating it? Floor covering? Lots more detail required or answers will be based on assumptions

And he should / could have used the opportunity to state all of that and book a return visit in. They didn’t. =💩

I use contactors every job, hence me saying it was my understanding that ‘they’ did this function. I’ve not used Shelly’s before, but they seem an elegant enough solution for not much money. @TerryE used solid state SSR’s to power up his heating and hot water gubbings, so the attraction is there if you want silent operation vs the clunk of a contractor. @RedSpottedSev, you may want to consider the clunking of 3 contactors and how / where you mount these things. Due to the size, I assume the Shelly’s are contactors and not SSR’s. Anyone living with a Shelly care to comment?

@canalsiderenovation Don't run back into the arms of these dickheads out of desperation. They've not done a good job here, just perpetuated their revenue stream and kept themselves in business. As part of their visit, they should have diagnosed, not just said "fit a bunch of new stuff". FFS. At the ABSOLUTE minimum, they should have asked to charge you for an hours labour, to check the red vessel pre-charge pressure, to ascertain what is going wrong. The system is too young to have major faults, this is a mountain being made out of a molehill IMHO. The issue(s) is NOT diagnosed well enough yet, so we need to know if the discharged water was warm or hot, and if the heating blew this off or the UVC did. Without this info you, and the aforementioned dickheads, are just flying blind. Leave the hot water on via the ashp and use your showers, you'll be fine for the immediate. Turn off the Solic, even though excess PV at this time of year is negligible anyways, which will reduce the magnitude of the situation.

Just put a 4th RCBO in the aux CU and run it to a double socket so you can plug stuff in downstream. Easier and cheaper to get this done in one hit if you’re getting a sparky out.

I thought the Shelly’s could be bought with switching capacity for direct connection to the immersion.

3 channels of Shelly’s is ample control and completely flexible.

Yes And yes. MCB’s aren’t usually used these days, as RCBOS offer better protection.

Simple fail-safe is to bridge L&N from the Shelly in(s) & out(s) in a local 20a DP switch (the type normally used to turn an immersion on / off anyways) and no heads go on any spikes If we do an UVC in an attic, I always fit the 20a switch in the living area somewhere, with a neon, and then the lady of the house just pokes that with her finger vs your left eyeball.

It’s down to the length of the cable, for voltage drop, and things like grouping factors, if run in a bunch with other cables quite tightly packed aka “contained” (trunking and conduit etc). You can hopefully run a 50a MCB in the primary CU and then fit 3x 16a RCBO’s in a secondary CU in the attic. Those each feed a Shelly, and then you use heat resistant flex from Shelly > immersion. You should use bootlace ferrules for the flex’s Link to make the best possible connections. How often do you think all 3 will be running? This is an all electric house with no heat pump? You can’t do this because of the high rating of the supply breaker. 32a max to a single socket or double socket or fused spur, fed locally via 4mm2 radial or 2.5mm2 ring. For eg, I swapped my electric shower for a thermostatic unit when I fitted a gas combi. The 40a MCB then feeding the 10mm2 cable got reduced to 32a (RCBO) and a BFO (60a) junction box went on the end of the 10mm2 cable where I made a new utility area. I came out of the JB with 2.5mm2 as a ring main, picking up 2x 1G sockets for the washer and the drier, and another for the boiler spur. You have to reduced the available current locally, or at source, to match the lowest current carrying cable in the chain; so you can’t have a 40/50a breaker directly feeding sockets or spurs.

He may have used a pump-up pressure bottle to inject, vs drain down and fill via a towel rad / other. Service guys don't like getting wet.......

1. Just start ringing local spreads tbh. 2. I'm no fan of taping and jointing, other than in a non-domestic setting. Plaster is the way to get the best finish, subject to the spread not being shite. Scotland folk often say that plastering is not common practice, so you may have to ring around a bit / lot. 3. Don't screw through cables or pipes! Select the correct length screws for each room.

Flexible tile adhesive. Always important to decontaminate the underside of the tray as they come covered in dust and mould release agents and so forth. I get a cotton dishcloth (old school ones are best) and use a bit of the tile adhesive made up a bit wetter and scour the underside of the tray until you see the adhesive wanting to stay on it. Then butter it a bit and you know it's going to stay put.

Ok. You’ll want to be able to push the tray side to side, lengthways, by 5mm (so 10mm of wiggle room), and to be able to have it 5mm away from the opposing wall. This will allow you to get the tray in, and to then be able to load all the gaps with clear CT1. You then mask the top of the tray on the 3 sides, frog tape or pvc electrical tape, and once loaded you push the tray towards the shower head end, and then back against the long wall, displacing the excess. Use (lots and lots) of cheap wet wipes to clean up the excess and then fill up the gap on the far end. Tool this into shape with a plastic packer and then peel off the masking tape. BINGO. Search wetroom and tanking on here and shower room for more info. And this may be a good read. Tanking the shower makes it bombproof. Been doing high end bathrooms for over 30 years and zero failures.

This person should have given you the correct solution at the outset, as your principal designer!! Another shining example of the differing levels of competency that are out there.

Only an option if you get permission to discharge storm water into the foul network aka ‘combined sewer’, otherwise you could be in a spot of bother if an issue ever occurs downstream.

Can you not use slabs? https://www.insulationuk.co.uk/products/150mm-superglass-superwall-32-cavity-wall-batt