Nickfromwales

Imho the risk of that back contamination is near zero. The scenario as Ive given above, which basically describes how this back flow contamination risk is born, incorporates a consideration to the volume of water needed to actually form such vacuum / siphoning and displays how hard it actually would be to put anyone OTHER than the householder at risk. If the shower handset went into the loo it would siphon about half a litre or a litre at the absolute most before the siphon ended and the backflow ceased. If, and I mean IF, the contaminated water got through the household pipework and into the network mains, and then got to the branch where the house was fed from then I'd go and buy a lottery ticket. With the NRV at the stopcock ( or in Dave's case multiples of NRV's ) stipulating that the shower handset shouldn't get into the loo because it could contaminate the network water is quite questionable. If the loo was constantly flushing and could maintain a siphon then MAYBE, but the odds of that 'perfect storm' scenario just don't seem to make this as big a risk as it's considered to be. Id rather consider the risk to the householder, which is imo the real one. .

Ok, let's clear this up. Situation could be.... Little Timmy decides for whatever reason to put the shower head in the ensuite in the loo. He walks off and plays Minecraft, blissfully unaware that the shower wasn't fully turned off after its last use. Meanwhile.....a plumber turns up and greets mum downstairs. "I'm here to fit your new kitchen sink tap luv". He turns off the stopcock ( which has the non return valve above it ) and opens the kitchen sink taps to let the hot and cold drain down. He goes upstairs to open the taps in the master bathroom and heads back downstairs to fit the new tap ( unaware that there is an ensuite ). After fitting the new tap, the plumber ( good looking welsh guy most probably ) turns all the taps back off and turns the mains on. He tests for leaks ( Da iawn, wrth gwrs ? ) and collects his payment and leaves. Sounds ok .........? No. With the water turned off and the kitchen taps open a vacuum was created. That allowed water to be sucked ( syphoned ) through the partially open shower valve, into the shower hose, out of the toilet, and then into the entire cold water system. It then has time to contaminate the pipework for the time the plumber took to fit the new valve. Timmy then has to brush his teeth upstairs before bed and the water that first comes out of the tap may have been part of yesterday's evening meal. Mum then fills the kettle and that's not great either. Even worse she fills the ice cube tray at the same time and the American fridge pulls it all in too, to be dispensed for the rest of the evening. @ProDave, that tells you how much protection your 3-4 NRV's would provide in this situation. ZERO ! ? Admittedly, the above is absolute worst case scenario, but hopefully allows you all a slightly rough as toast scenario / example to help understand why that type of reg is in place .

NOTE : The chat about electrical bonding and plastic pipe work is continued here :- ( Topic moved to allow this thread to stay on track ? )

A very good point @Barney12 Might I ask that you start a new thread please? . Better than losing that in this thread and going too far off topic ?

Just the wording "if the ashp cannot x y z" that was a bit misleading We'll get there I'm sure

Get it changed immediately before your rights expire. . When they deliver the new one examine if closely for similar defects etc. If found, at least you'll have a BNIB unit which you could sell / return for refund ( if possible ). Dont fit it until your 100% happy with it. Deal with Stanley direct and explain your concerns, but only after you have the new unit in your possession. My mates hot tub had multiple failures so he fought for a replacement. It had to be craned over the house at his cost. After a load of grief off them he agreed to pay the new crane fees, begrudgingly. When they arrived with the hot tub the crane was set up in the street ready to go. He told the spa Co that he only had 15mns of crane hire left and the original tub was still being disconnected, so they agreed to crane the new one in immediately. As soon as it hit the ground and the crane was detached from the strapping he escorted the spa Co staff out of his home and told them any attempt to reenter would constitute trespass. He retained the original spa and told the company if they wanted it they would have to rearrange the crane at his convenience and that would only be when the new one was proven to be working properly. They never came back and never contacted him again. He sold the u/s one for spares to recover his time and losses. Took 7 of us to 'hedge hop' it over the neighbours gardens. Moral of the story, if they can get off the hook they usually will, so act sooner than later. .

I think you mean that you will set the ashp to NOT go into DHW mode purposely? The cylinder will reheat via the cyl stat, regardless of what the instant is / isn't doing. I think that logic needs a revisit unless I've mis-understood you?

BUSTED!

"Don't trust this man"?

Agreed. Anorher way to cheat around a cheaper unit is to fit an aftermarket TMV on the outlet to cap the max temp .

There are over 6 million shades of beige.....what's not to like Exactamundo! My point was about not getting end panels and other such non-interchangeable items done in "baboons arse" purple, or the skin of 101 Dalmatians . @recoveringacademic may not thank me for that idea being planted . I choose to die of natural causes thanks v much .

Probably best to first define which heater is best suited to what application / why etc. Some of the smaller instants are 'over sink' which means they cannot be connected to a tap or other outlet, then there are under sink instants, and then both variations with varied volumes of stored water, commonly referred to as water heaters ( not instants ). That would all depend on whether or not you wanted to see it or not I suppose. And, more importantly, if it needed to be connected to a tap or if you'd be happy with the rather crappy swivel spout / arm outlet. For basins in particular, anti-scald measures are more of a concern than flow rates imo

I think there is a big jump between thermostatic and fully modulating. The former still is quite crude, with the latter near flawless in its delivery characteristics.

Probably as good a place as any to impress upon folk the need to strip and clean these filters / strainers directly after commissioning, and again after about a month or two of normal service ( use ). Any crap in the incoming supply (new MDPE etc.), or solder, flux, PTFE tape and jointing compounds can get to / and sit on the valve seat and cause it to malfunction. The effect of that failure is for mains pressure to get past the non-sealed seat and damage upstream equipment.

1) Reliance 2) Caleffi 3) Ariston

In @TerryE's instance, the stainless steel gauze filter in the PRedV should be all the filtration required TBH. If, post PRedV, the fill point is drawn for the heating / HP etc then that primary measure should suffice.

Diaphragm, filter, spring and adjustment screw for the pressure setting.

Do you have sufficient volume and head to not require a secondary pump for the rainwater? Do you have filtration on the primary and secondary sides?

It's one I did 1st bank cold 2nd bank hot @ 51oC 3rd bank hot @ 46oC ( basins) 4th 2-port out of view was 2 x hard water. One to kitchen sink & O/S tap ( back to back ) and the other to utility cold and boiler fill loop ( back to back ). 2 x TMV's for each temp zone Black thing is a 2 Ltr hot water expansion vessel. Blue cylinder is a 500 Ltr Telford TS with a 46kw 28mm DHW heat exchanger ( coil ). ?

With no dependants / infirm in the house there really wouldn't be any need for the second drop down, other than for comfort / convenience. I prefer the latter, so I have one in my house. The joy of just flicking the tap on at the full hot position and having comfortably hot ( user definable of course as TMV's are fully adjustable with a simple turn of an Allen-key ) is what I like. No flicking the tap between hot and cold to get the right temp, then the pipe work temp stabilises and you have to readjust it, then someone flushes a loo elsewhere and you have to adjust it again........why do this to yourself for change of £40? @TerryE, your old farmhouse would have had a large bore ( 22mm or bigger ) DHW pipe work setup with full bore taps and no restrictive valves such as a TMV. The flow rate therefore would have been good or very good. When you introduce 15mm pipe work though a PHE, then take it through a TMV, you have to start adding the various resistances together and summise from there. As that TMV is 1" body by default, then I'd use a piece of 28mm pipe coming out, going into a 22x22x28mm compression tee, ( Demountable for servicing ). Then 22mm to each manifold.

Evening squire As you've got 2x 15mm outlets on the SPV's which are combined to give flow from both units simultaneously ( in parallel ) then there is merit to go to the 28mm TMV for reduced flow restriction and increased litres per min at the set temp. The questions are :- Do you ever see that many hot water outlets being used simultaneously to warrant such a decision? Will the incoming cold mains be man enough to allow this max velocity to be a realistic consideration? The flow through a 22mm TMV is really quite high tbh, and to give one example I previously fitted a 450ltr TS for a customer which had 22mm TMV set to 51oC. I ran both the showers simultaneously and the kitchen sink and they all ran more than adequately. There was a 300ltr cold mains accumulator to reinforce the cold main so it could maintain these rates, but the hot side certainly didn't seem to struggle at all. It may have if a bath was in the picture but running the bath whilst 2 showers are being drawn is a bit extreme. Anyhoo, a fortune? Check this TMV out. And, drum roll please........... Wales delivers once again

Agreed. Bold colours on anything other than ( interchangeable ) doors isn't a good idea IMO. I've talked some people out of crazy tiles, and after choosing again they've thanked me. Some people have told me to FO, and stuck with their first choice. One the other day walked in, looked at the tiles, squinted and said "oooo, they look a lot different when they're up, what do you think?". I smile and say they look lovely. That, plus the fact the adhesive has gone off and it's too late to pull them off and bin them

Words are like weapons.....they wound sometimes. But not this time Stare at that damn penny floor until you love it.

Oh, and thanks for keeping my bizarre flooring thread on point