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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?
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 ?
Just random thoughts, please feel free to ignore.
I've never put any sort of relays in, but the most we fitted was 3 showers on one 100A supply in a house which had no problem.
Don't forget the chances of people all showering at the same time in a single house are pretty slim, especially since the water pressure would drop away to a dribble!
Theres no need for relays, just fit a shower priority device which negates any chance of an issue, or a dribble
Shower Prioity Units | MeteorElectrical.com
That is a board with relays/contactors.
Yep, ready built, tested, approved, proven - not built using bits found in the back of your van
I'll double check with Western Power, but having spoken with them about the maximum size single phase domestic connection & them saying it is 100amp I can have, I will be pretty annoyed if it is the old 65amp service. Thanks for the reminder.
ha ha Sean, it might be more accurate and friendly to say ‘your truth’ is different to ‘my random thoughts’.They are very random thoughts, especially as the opposite of what you've posted is true ...
And not amm3 compliant so would have to have an enclosure built round it. TBH I have enough confidence in my ability to build my own if I never needed to......i was just pointing out that they are contactors/relays as you said no need for relays.
ha ha Sean, it might be more accurate and friendly to say ‘your truth’ is different to ‘my random thoughts’.
My thoughts are only based on what I read at this website, Why Passivhaus to summarise my understanding, or lack of:
it’s a precise standard worked out by boffins. Comes with certification and approved contractors/ and architects You tweak it to save money at the building stage and it’s not the ‘real deal’ ie not certifiable, therefore the USP vanishes, leaving an devalued asset that‘s harder to liquidise. In the real world with all it’s uncertainties, changes, shocks, and surprises that's not a good thing to do with a significant asset.
ha ha Sean, it might be more accurate and friendly to say ‘your truth’ is different to ‘my random thoughts’.
My thoughts are only based on what I read at this website, Why Passivhaus to summarise my understanding, or lack of:
it’s a precise standard worked out by boffins. Comes with certification and approved contractors/ and architects You tweak it to save money at the building stage and it’s not the ‘real deal’ ie not certifiable, therefore the USP vanishes, leaving an devalued asset that‘s harder to liquidise. In the real world with all it’s uncertainties, changes, shocks, and surprises that's not a good thing to do with a significant asset.
My second point is based on me buying and selling houses.
Dual fuel or three or four types of energy taking advantage of the efficiencies and benefits costs of each type is the preferred option.
Yet another gap in my understanding, I cannot even visualise what some of the items will look like, I’m probably well off the mark when I think of instantaneous water heaters, do they look like something you’d find in a Portacabin on a building site ?
Maybe what I’m saying, is if your going down the Passivhaus route, do it right, using the tradesmen and professionals they recommend (or in reality have paid for the Passivhaus ticket). Whether or not, as others suspect the OP may be attempting the electrical installation, with an largely unpaid mate in background to attempt to 'legalise' his DIY on the electrics is none of my business. :lol:
It's a very interesting topic. To the OP thanks for starting it, and I wish you every success with your project.
Probably if not cheaper.Could you build the same for that price ?
Probably if not cheaper.
You've obviously forgotten what it's like to be a teenager. Turn on shower, wait ten minutes for it to warm up nicely, then have shower for 15 minutes, cos I'm not paying the bill.Don't forget the chances of people all showering at the same time in a single house are pretty slim, especially since the water pressure would drop away to a dribble!
No probs at all Sean, I just put the ‘friendly’ bit in for a laugh - hence the cheeky tongue emoticon.That wasn't supposed to sound unfriendly, sorry.
Watching ManU V southamton - I have beers here, that need to be drunk.:17:
Have a nice weekend all.
half time - nope MUTV you streaming it ?? LOLi smell something illegal here. Lol
half time - nope MUTV you streaming it ?? LOL
Completely off topic fact - in the last 11 Utd home games, there's only been 1 goal
0-0 0-0 0-0 0-0 0-0 0-1 0-0 0-0 0-0 0-0 0-0
no need for that. Im very happy with LVG work.
you must be a Southampton supporter ?
Time for LVG to go, he’s only cruising to retirement imo. He’s not the long term future.
Back on topic.
As a trainee, hope it's OK to ask this question.
When the customer decides to buy his own fittings etc, doesn’t that mean he assumes full responsible for dealing with potential warranty issues. ?
For example, say an instantaneous water heater stopped working, you could charge for troubleshooting, then leave the customers to liaise and arrange for a replacement from wherever he purchased it from. Then charge to re-fit and test ?
You'll also be able to claim the VAT back on the materials...if he is non VAT registered you couldn't if he supplied them...and if he was it would be zero VAT anyways (assuming this is a New Build)In this case I am only buying my own fittings/materials as I was told to by my sparks. He is wanting to save me money as a friend rather than him spending time he doesn't have sourcing the best prices for materials.
I thought he would want to buy them all as normal, but his response was "if I supply them, I'll get them from my normal source and add the normal markup - you discuss with me what you want, I'll advise you and then you source those materials and products as cheaply as you can"
He's a good bloke
You'll also be able to claim the VAT back on the materials...if he is non VAT registered you couldn't if he supplied them...and if he was it would be zero VAT anyways (assuming this is a New Build)
He's a good bloke
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