running two electric showers at same time

Can someone advise on this please.
Scout hut extension and plumber is installing two mains water electric showers. I have raised the question that what if two children were showering and the toilets was flushed, will their be a possibility of scolding due to flow dropping. I only mentioned this as in mum in laws house any use of cold water causes rapid temp variations in the shower. Also if the two showers are in use will their be a balance problem between the two as to which one gets the most water and then starts a war of users messing with temp control on their shower. Builder rang me and said I was shoot stirring, don't really care as long as none of the children in my care end up with scolds.
Many thanks, Jack

In truth it depends.

the main factor will be the size / bore of the mains supply to the hut.

any group usage will affect the flow to any individual unit. but if the flow and / or pressure drops too low it should cut out for safety.

Flow restrictors should sort the problem - after a fashion - although they might not be suitable for electric showers.

You can't put a flow restrictor on a electric shower.

Most electric showers contain anti-scold features but I've not tried one to find out if they work!

I have to say that in my experience all electric showers are pretty useless.

I guess there not after a luxary showering experence, just a way of getting clean!

As said ive seen showers advertising anti scauld. Obviously on a conventional shower you can have a thermostatic mixed, which do work really well, but it wouldnt be beyond the wit of man to have a temp probe in the flow and have some sort of cutout.

Daniel

I hope the electrical supply is capable of powering two electric showers at the same time. (Plus the rest of the Scout hut requirements, lights, power, heating etc.,)

Two 10 kW showers alone will take nearly 90 Amps.

Since most dometi csupplied are either 60A or 100A that seems a little close to the limit. Particularly if electric heaters or kettles are used!

But you did say it was a builder and not an electrician!

Tony

Agile said:

But you did say it was a builder and not an electrician!

Click to expand...

Could well be less powerful showers. That would be my solution.


Daniel

Most electric showers have no real control of heat.
You set the amount of power depending on the flow rate of water
any variation of pressure will mean the showers temperature
varies quite badly. I have exactly the same situation in my sisters house
where they have an electric shower and if anyone turns a tap on the temperature in the shower is badly affected. It gets very hot quite quickly.
(another builder who decide to restrict a 3 bathroom house to 15mm cold main and a combi boiler!)

I would suggest fitting an accumulator tank to compensate for pressure variations.
I would also suggest that the builder takes a shower when installed and you flush the toilet as a test if he doesn't run out of the shower without adjusting the temperature control then its ok. Advise him that if he does leave the shower you won't be paying and he will have to fix it.

My other worry is similarly the amount of current these showers will be pulling. If they are 9.5kw then that is near enough 80amps which doesn't leave much and you will blow the 100amp fuse

I would query whether electric showers are suitable at all for this environment.

Although they're supposed to be waterproof and mounted within the cubicle, I wouldn't rely on children not aiming the spray in all directions and getting water in the electrics. You also have to allow for the case being damaged or vandalised and you not noticing.

If the spray is obstructed (eg to get a better 'squirt') the temperature will increase, this may mean a sudden rush of very hot water when the obstruction is removed.

If the spray is obstructed to the point where the pressure relief opens, then (possibly very hot) water will be discharged unexpectedly from the base of the unit.

It's possible on many models to leave the shower set on 'hot' so the next user gets a nasty shock.

Most electric showers aren't designed for commercial use and if the instructions say 'domestic use only' then fitting them would be a breach of manufacturer's instructions.

In this case I would strongly suggest a vented stored hot water system (gently pumped if header tank height is not adequate) using anti-scald mixing valves designed and rated for healthcare facilities with pre-set max levels that can't be tampered with. As a 'public' facility the showers might be used by people with disabilities who can't get out of the way of hot water quickly.

A bonus would be you can use water-saving 'press to spray' handsets or fixed roses (which you can't do on an electric shower) thus saving hot water and preventing flooding from showers being left on and the drain holes being gunged up with toilet paper.

I expect this may be a situation where with young children the antiscald valves are needed and that electric showers would not be suitable.

I made a mistake saying that they were to be installed by a builder, the builder was accusing the OP of meddling but the fitting was actually stated to be by a plumber.

If so then I hope he understands the electrical supply requirements for them to be protected by RCDs etc.

Tony