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Repurpose electric shower supply for common goods

Postby Schmobi » Mon Oct 12, 2020 8:54 am

Hi. I am renovating my bathroom and have removed the electric shower. I have a gravity-fed hot water supply and am planning to install a pump to give a reasonable pressure to a shower fed from a mixer tap.

The electric shower was on its own circuit. I'd like to use the cable to now power the pump as it happens to be conveniently located next to the boiler. I think that this might be as simple as installing a 13A fuse spur and replacing the previous switch with a 3-gang socket. Is this right, or is there something I should be aware of? Is the circuit for the electric shower going to be too high-voltage or something?

Many thanks.
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Simply Build It

Postby Mr White » Mon Oct 12, 2020 6:58 pm

What watt was the shower?
I am thinking the cable will be too big to be installed into a socket.

You can not "Just add a pump" to a gravity fed hot water system. You have to have a "Deleted flange" attached to your hot water cylinder and connect the pump to that, if you don't (and some people didn't) the cylinder can get cavitation and the outside air pressure can crush the cylinder.
You would be best advised to get a heating engineer in to advise you.
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Postby ericmark » Mon Oct 12, 2020 8:44 pm

I did it, the pump was built into the shower unit so looked like an electric shower and was connected up same way as one would connect an electric shower, with RCD protection etc. just swapped the MCB to 6 amp instead of 40 amp.

It was the plumbing that was the problem, you have to ensure it can't empty the cylinder. If it can result in air in cylinder then the immersion heater can burn out, I took advice and did as told.

Then after all the work, my dad found the header tank leaking and decided to have a combi boiler fitted so all had to be altered as it would have been illegal to pump from the incoming main.
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Postby Schmobi » Tue Oct 13, 2020 7:50 am

Thanks for your responses.

A plumber is installing the pump. From what I can see looking at the manual, the pump can be set up in such a way that it is connected to a device in the loft which switches it off when that supply runs out. Hopefully the plumber will sort all of that out. I'm only doing the electrics for this bit.

I think I have the answer I need, which is that yes, I can use this circuit. Thanks a lot.
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