Nickfromwales

One per vessel, so 1x red, plus 2 (or 3) for the white vessels.

Ask these guys for a full diagnosis of the fault, and why it’s occurred, and the solution. Otherwise you’ll be doing this over and over again.

Ask them to supply a 3rd vessel. The valve is in the first page of this thread with Screwfix part number visible

Yup. No getting away from intumescent strips here I’m afraid. Wouldn’t pass muster with BCO but will also be in your b regs spec.

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?