14 new 9.5kw showers to be installed on existing supply

[telectrix]

grrr. just what i was about to suggest. timers and contactors.

 

[i=p/u]

Say for8.5kw half being used at one time 7 x 36= 252 , and if you have possible 375, I would go with this as said why not go with 8.5kw for starters as people just turn the setting down to 8.5kw anyway I.e around 30A...

 

[i=p/u]

But the priority system would be the best....... And controlled

 

[Guitarist]

With a couple of timer switches and a few TP relays you could quite easily fit a shower supply system in a central location that would force staggered use, say three showers (could be more? Up to you..), one on each phase for 30 mins, then the next three showers, then the next three and so on... No leccy supply issues, no water pressure issues, and all that will have changed is that residents will have to conform to a specific time regime for showering otherwise they will miss their slot and have to wait an hour or two (depending on how many showers you allow to run at any one time) till the next time slot for showering.

Problem solved!

I can see that working......

 

[telectrix]

I can see that working......

easy. program 1 shower for january, 1 for february......... keep the remaining 2 as spare.

 

[D Skelton]

I can see that working......

TBF, sheltered accomodation, the likely residents being bums, contrary to popular belief, if there's one thing bums cherish above all else it is a shower! So yeah, I can see it working

If someone was to choose not to use their allocated time slot for a shower then that's their choice at the end of the day. The facility is provided, end of.

 

[simpson93]

Just don't let them put it there showers past Eco mode.

 

[Guitarist]

I typed a lovely long reply, but it got wiped by the system, so I'm not doing it again. Had enough now!
Glad you see a rota system working, because I don't. Just my opinion.

I'm logging out now until someone messages me to say that this site is fixed, so I may never be back.
Just gonna pop a post in general before I go.
Bye bye guys.

 

[Gavin A]

This is probably still pretty borderline, but might be acceptable...

Fit 7.5kW electric showers. Fit pressure reducing valves before each shower to limit the flow to the shower to eg 1 bar to minimise the pressure changes in the flow, ensure it's hot enough - and make sure the plumber fits a high capacity pipe to provide the main feed for all the showers.

(2 x 7.5 x 100%) + (3 x 7.5 x 25%) = 20kW / 230 = 86amps

That is going to take you above the 100amps, but as the load is only likely to be short duration - 10-15 minutes, and it's only actually likely to be 5 showers in total during any given period as it's one person per room (i assume), I'd think there's a reasonable case for thinking this could be acceptable. Even at 15 minute showers, that's still only 9.375kWh in total for the 5 showers, spread over half an hour would give an average power draw for that half hour of 18.75kW or 81Amps, which matches quite well with the diversity calcs.


A 100Amp fuse will allow 150Amps to flow for half an hour or so without blowing, or 170Amps for 10 minutes (ish) so I can't really see that there's much danger of that from the showers while being used normally... if I'm reading the curves right.

A lot depends on the other loads in the building though, if there's electric heating, cooking etc then it's probably not going to work.

Interested to see what others would say to this suggestion though, as I deal with this stuff from the generation end of the spectrum mostly, and volt drop is my main limitation rather than current usually. In a previous life I did used to spec generator capacities for festival sites though, which involved similar calculations and considerations.

 

[matthunt]

This is probably still pretty borderline, but might be acceptable...

Fit 7.5kW electric showers. Fit pressure reducing valves before each shower to limit the flow to the shower to eg 1 bar to minimise the pressure changes in the flow, ensure it's hot enough - and make sure the plumber fits a high capacity pipe to provide the main feed for all the showers.

(2 x 7.5 x 100%) + (3 x 7.5 x 25%) = 20kW / 230 = 86amps

That is going to take you above the 100amps, but as the load is only likely to be short duration - 10-15 minutes, and it's only actually likely to be 5 showers in total during any given period as it's one person per room (i assume), I'd think there's a reasonable case for thinking this could be acceptable. Even at 15 minute showers, that's still only 9.375kWh in total for the 5 showers, spread over half an hour would give an average power draw for that half hour of 18.75kW or 81Amps, which matches quite well with the diversity calcs.


A 100Amp fuse will allow 150Amps to flow for half an hour or so without blowing, or 170Amps for 10 minutes (ish) so I can't really see that there's much danger of that from the showers while being used normally... if I'm reading the curves right.

A lot depends on the other loads in the building though, if there's electric heating, cooking etc then it's probably not going to work.

Interested to see what others would say to this suggestion though, as I deal with this stuff from the generation end of the spectrum mostly, and volt drop is my main limitation rather than current usually. In a previous life I did used to spec generator capacities for festival sites though, which involved similar calculations and considerations.

Hi Guys, remember these particular types of load being resistive are based on 230v, in all reality the voltage will be higher so the current is proportional to voltage, so if voltage goes up then so does current. Arguably a 7.5kw shower will never operate at 7.5kw as this would be the maximum rating on the highest temperature, but again you need to be aware of the incoming voltage.

 

[Geoffsd]

But the 7.5kW (or whatever) will have been quoted by the manufacturer at 240V.

If this were a block of flats with similar supply would anyone bother to find out what was already installed on the same phase if one (or two) wanted a shower fitted?

You could end up with the five on the same phase having showers but none on the other two phases.

 

[matthunt]

But the 7.5kW (or whatever) will have been quoted by the manufacturer at 240V.

If this were a block of flats with similar supply would anyone bother to find out what was already installed on the same phase if one (or two) wanted a shower fitted?

You could end up with the five on the same phase having showers but none on the other two phases.

Hi Geoff, the Manufacturers rate their equipment at 230v in line with European

 

[telectrix]

230, 240, who cares. they only guess anyway.

 

[matthunt]

Hi Telectrix, makes a difference with the calcs as at 240v a shower will use more current than at 230v, take a look at John Whitfields Guide to the 17th Edition, anyway we digress, its too many showers through a single connection point so call the plumbers in

 

[telectrix]

job's bad enough without getting the wet-pants idiots to screw it up even more.