2 x showers plus electric oven

[flameport]

He assured me it wouldn’t be a problem once I sort the water pressure as they “never run full rate” and “diversity etc blah”

An electric shower uses the full power for the entire time it is in use. The only exception being if it's set to half power or cold - but no one uses those ever, so irrelevant. Temperature control is just varying the flow rate through the shower, more flow = cooler water.

I could change the electric in the en-suite and pump the hot to a mixer shower but I’ll still have the problem of mix / pressure drops on the cold feed if I go that route?

For a pumped shower, both hot and cold should be pumped with the cold from the same cold storage that supplies the hot water cylinder.

Unvented is only an option if you have suitable pressure and flow from the cold supply - otherwise it will be useless.

An electric shower and electric cooker is far better than two showers, as the cooker won't be using the full power all of the time - the various elements will switch on and off to maintain the temperature.

 

[FRAN1870]

An electric shower uses the full power for the entire time it is in use. The only exception being if it's set to half power or cold - but no one uses those ever, so irrelevant. Temperature control is just varying the flow rate through the shower, more flow = cooler water.


For a pumped shower, both hot and cold should be pumped with the cold from the same cold storage that supplies the hot water cylinder.

Unvented is only an option if you have suitable pressure and flow from the cold supply - otherwise it will be useless.

An electric shower and electric cooker is far better than two showers, as the cooker won't be using the full power all of the time - the various elements will switch on and off to maintain the temperature.

I know unvented could actually make matters worse by reducing flow on the cold side (robbing peter to pay paul).

Electrics wise I could still in theory have a situation where the cooker is on full whack at the same time as the one shower? 40amp shower and 32amp cooker? could easily be more than 60amps
Obviously this situation will be less risky than two leccy showers but with two high use appliances (plus all the other things in the house) I could easily bypass the CU 100amp and blow the main 60amp CO fuse?

As for the water I'm not really talking about a power shower in the traditional sense.... my plan at the moment (albeit expensive) is to have an 210L accumulator tank plumbed on the main in the utility room. This should give me house wide improved pressure and enough flow to run whatever showers I need while flushing the toilets and doing the washing. As the cold with be up to standard I won't need to pump it and should be able to have a thermostatic mixer shower by only pumping the hot feed from the tank on demand with a salamander or similar? (providing the tank is big enough, yet to be assessed.. I think its a 110L)

This does a few things ...
1: Eliminates the need for two electric showers
2: Free's up an existing 10mm feed to run the oven(s) circuit .... (so I won't have to run a new cable the length of the house, which believe me is a pain in the backside).
3: Paves the way for an unvented hot water system should I win the lottery

Does that sound like a sensible solution?

 

[AndyPRK]

rather than say a 40amp shower and 32amp cooker, use their KWatt ratings. Add them, and divide by 240v to get the total amps. You will like the answer better I would think

 

[FRAN1870]

rather than say a 40amp shower and 32amp cooker, use their KWatt ratings. Add them, and divide by 240v to get the total amps. You will like the answer better I would think

Ok ...

8500 watt shower
5000 watt cooker

13500 / 240 (although I thought everything was calculated on 230 these days?) = 56 amps so not much left over for everything else?
I know we could be selective about which cooker to go for but more amps opens us up to more options?

For the sake of changing the main CO fuse? Hopefully the incoming mains is sufficient and if so is there a reason why I shouldn't get it changed for free?
Even 80amp would be enough?

 

[flameport]

As the cold with be up to standard I won't need to pump it and should be able to have a thermostatic mixer shower by only pumping the hot feed from the tank on demand with a salamander or similar?

That may work, but is asking for problems. Showers require both the hot and cold to the the same pressure, which is why a pumped one has both hot and cold pumped - the cold supply pressure can and usually does vary over time so is unlikely to be the same as from the pump.

Hopefully the incoming mains is sufficient and if so is there a reason why I shouldn't get it changed for free?

You may get a fuse changed to a higher rating for free, as that is a quick, easy and cheap thing to change.
If the cable is too small, changing it to a larger one will definitely involve paying for it. There are no free upgrades.

my plan at the moment (albeit expensive) is to have an 210L accumulator tank

What is the cold supply pressure and flow?
Upgrading the supply may be an option, and not necessarily more expensive than the accumulator.

 

[Taylortwocities]

You cooker will be way less that the theoretical max stated.
For some devices, we apply a technique called diversity.
5000 amps @ 240v is about 20 amps. For domestic ovens we count 10 amps plus 30% of the remainder, so that means your estimated demand for the oven will be around 14 amps.
As stated above. we cannot use diversity for instant heat devices like showers.

Have you ever thought about adding up the value of all of the MCBs in your consumer unit. Mine adds up to about 200 amps!
So how come the main fuse doesn't blow on a weekly basis? Its because not everything is going 100% of its possible maximum all of the time.

 

[FRAN1870]

You cooker will be way less that the theoretical max stated.
For some devices, we apply a technique called diversity.
5000 amps @ 240v is about 20 amps. For domestic ovens we count 10 amps plus 30% of the remainder, so that means your estimated demand for the oven will be around 14 amps.
As stated above. we cannot use diversity for instant heat devices like showers.

Have you ever thought about adding up the value of all of the MCBs in your consumer unit. Mine adds up to about 200 amps!
So how come the main fuse doesn't blow on a weekly basis? Its because not everything is going 100% of its possible maximum all of the time.

Yes of course ... silly me, I didn't look at it like that so thank you for explaining.

Back to the original installation... Can I take issue with the bloke who I paid to put the second electric shower in if that's the case? Surely he should of advised me that running two electric showers on the 60amp circuit was pushing it given that diversity doesn't apply?