Nickfromwales

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.