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Op is gonna have electric shower.30liters on a bad day....do you an your partner not shower at all then?
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Op is gonna have electric shower.30liters on a bad day....do you an your partner not shower at all then?
Hi Justin,
They seem to me to be a daft way of heating lots of water that we'll never use. As I have said previously, clothes washing happens in a washing machine, dishes in a dishwasher. The amount of hot water we will use in a day isn't likely to be more than 30 litres on a "bad" day. The smallest type of tank is normally 4 times that size!!
Cheers
Well, as others have already pointed out, that heating load will need some very careful thought, and probably some sort of "hard" interlock to prevent the all operating at once. It may be unfortunate for someone having a shower if the kitchen is using the load though.
Personally I think hot water tanks are very good, and the heat loss from a well insulated tank at moderate temperature (say 55C) is pretty good. Assuming PIR foam 100mm thick, (U 0.2), for a 2M x 700mm tankful of water at 55C, that comes to about 36 watts. - Still too much to be loosing, give the convenience?
3 x 12KW + 9.5KW ! You are out on a real journey with this one! I have no solution other than some sort of TBD interlock. Let us know how you get on.
Don't know if Justin missed my post about abandoning the 3 x 12kw heaters?
Anyway we have now decided on...
2 x Redring RP1s @ 9.5kW each (rated at 240v, at 230v only 9kW/40amp)
1 x Stiebel Eltron SHU 5 (2kW, 5 litre unvented) - it uses .31kW in 24 hours to maintain the water temperature once heated.
I feel much happier with the expected usage from an electrical safety point of view, and I have the comments made in this thread to thank for that. I guess maybe a handful of times in a year 2 of the 9kw items might be used at the same time for a moment and that still only gives 80 amps for maybe 30 seconds, allowing 20amps 4.5kW for other things if they are on at the same time.
It would be interesting to know exactly how much current they actually use when they are running, they may very well have multiple elements totalling 9.5kW but not always use that much. I've found some 9kW showers actually include a thermal switch so that only one of the elements runs if it gets hot enough on its own (4.5kW)
At the risk of embarrassing myself, I don't know of a way to measure the current draw - is there an easy way to do that?
It would be interesting to know exactly how much current they actually use when they are running, they may very well have multiple elements totalling 9.5kW but not always use that much. I've found some 9kW showers actually include a thermal switch so that only one of the elements runs if it gets hot enough on its own (4.5kW)
Two 9kW demands would total 80A or so and so long as the anticipated demand from the rest of the property was below 20A then there would not be a problem. However each situation would have to be assessed on the anticipated maximum demand in reality.A bit off topic but along the same lines. What is the score Dave with a domestic property proposing to run 2 x 9kW electric showers from a 100A main fuse that don't have the ability to switch off one of the elements? My understanding is that it is a obvious no no due to the current draw, unless you have some sort of relay that will switch off one, when both are switched on at the same time.
I assume you could employ the same sort of idea in this case with the 9.5kW heaters?
I was sizing up a job today in a pub that needs a rewire in the living accommodation upstairs and it needs another electric shower, fortunately it has 2 x single phase 100 amp supplies, the existing electric shower it is on one supply that was drawing 55 amp on my clamp, the other drawing just 16 amp which will supply the upstairs and new shower, so not a problem.
Just I am not familiar with this relay switching if anyone could enlighten me?
OP your electrician should have one. Normally clamp around the tails for this measurement, but best left to him. But measuring will be like locking the stable door, after the horse has bolted. You need to consider the design first, as davesparks mentioned earlier.Yes, we use a device called a clamp meter.
OP, I remember someone pointing out to check the rating of your supply with your DNO, have you done that yet?
Take your point it’s not an investment.
That’s good, because with respect you may be creating something, were no one would want to lend on, or buy it, without wanting to knock you for cash to conventionalise it. What’s the point of investing in a significant asset that can’t easily be liquidised ?
Tweaking a concept or standard downwards until it doesn’t achieve the criteria of the concept or standard is counterproductive to any USP attached to the concept.
Just random thoughts, please feel free to ignore.
hi Janner43
be a little careful with MVHR unit to do the most of the heating I know of a heating engineer that was working at some new build places & the developer did not put in any heating just MVHR units & it was cold in the winter & too late for them when it was finished.
on a course for MVHR units few years ago with a guy who was working on a passive house with very good insulation values, they were even putting 20mm conduit through walls for the outside lights when first fixings so no losses through cavities & then silicone the tube when wires installed & then again when light fitted trying to keep air tight.
sockets bagging around the back sides creating a seal as such to the outside.
used some MVHR units with wet rads inside them, they have temperature sensor mounted inside the unit which then feeds a stat that opens heating valve & heats the air coming into the property making them even more efficient.
another thing to keep in mind that manufactures do not tell you is what to do with unit should there be a fire I rang one company about this they said down to installer no guidance.
we installed heat detector in loft with unit & on a relay base N/C should fire detectors go off we stopped the unit. did not want to give the fire one of the elements it needed.
hope it helps
A bit off topic but along the same lines. What is the score Dave with a domestic property proposing to run 2 x 9kW electric showers from a 100A main fuse that don't have the ability to switch off one of the elements? My understanding is that it is a obvious no no due to the current draw, unless you have some sort of relay that will switch off one, when both are switched on at the same time.
I assume you could employ the same sort of idea in this case with the 9.5kW heaters?
I was sizing up a job today in a pub that needs a rewire in the living accommodation upstairs and it needs another electric shower, fortunately it has 2 x single phase 100 amp supplies, the existing electric shower it is on one supply that was drawing 55 amp on my clamp, the other drawing just 16 amp which will supply the upstairs and new shower, so not a problem.
Just I am not familiar with this relay switching if anyone could enlighten me?
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