DIY Doctor

Power Shower - do you need a tank?

Postby farida » Tue May 27, 2008 5:48 pm

I am having my whole house rewired and want to put a power shower in. I don't seem to have a cold water tank or any tank for that matter. The cold water pressure is quite high anyway but the hot water is low. What should i do? The electricians started their work today and i would like to be able to tell them what they need to install with resepect to electrics for the shower.
Thank You :)
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Postby plumbbob » Tue May 27, 2008 8:17 pm

Have you checked in the loft? If the hot water can be easily stopped by putting your finger over the tap, it's reasonable to suggest that you have a cylinder and tank somewhere. Is it shared heating?

You must have a tank for a power shower as the pump needs somewhere to draw the water from.

Do not rely on the flow of water to identify what type of heating you have, old instant or combination boilers often produced just trickles of hot water.
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Postby chris_on_tour2002 » Tue May 27, 2008 9:55 pm

do you have a gas fired boiler?

you need to ascertain what type of system you have.

from the sound of it i'd guess that you have a combi system which would explain why you have no tanks/stored water and why there is good pressure on the cold and reduced pressure on the hot.

given the absence of tanks and if it is a combi system then a power shower is a non starter as you cannot legally pump the mains supply.

i'd start looking for alternative showers unless you want to go to all the expense and trouble of putting water storage tanks in.
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Postby rosebery » Tue May 27, 2008 11:12 pm

Do you mean a power shower or do you mean an electric shower?

You worry me that you seem nt to have any tanks but you have differential pressure on the hot and cold. That implies that the cold is mains and the hot is gravity fed from a tank.

Anyway if you want a power shower then you need to have balanced pressures on hot and cold which means feeding both from the CWST (albeit the hot comes from the HW Cylinder the pressure is provided by the head of the CWST) before pumping both to the shower. Normally the pump goes in the airing cupboard with the cylinder. But if you haven't got any tanks..........

If you mean an electric shower these run off mains COLD water ONLY. The electrician should know what needs to to run a separate supply from the consumer unit. The size of cable will be dependent on the run and the power (in kW) of the shower you intend to fit.

Hope that helps initially.

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Postby farida » Fri May 30, 2008 3:10 pm

Thank you all for replying. It seems that a power shower isn't an option due to no tank.
Is there any other way to increase the flow to the bath shower. I do have a combi system - installed a couple of months ago.

The electrician gave me the quote based on fitting an electric shower (i thought that was what i needed) and although he is saying i don't need it, he is not going to reduce the quote by more than #100 pounds if i decide not to put it,

So.....Is there anything else i could put it in instead?
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Postby bobplum » Fri May 30, 2008 8:59 pm

have just skipped thru the question so i apologise if this wrong
i get the impression you have cold mains and a hot water tank
if so then you may be able to fit a water pressure equalizing valve and fit a pump to that to give a power shower
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Postby chris_on_tour2002 » Fri May 30, 2008 9:25 pm

on your boiler there will be a dial with a picture of a tap on it - this adjusts the hot water temp. turning it down a touch will give a little more pressure but should still be hot enough for a shower.

unfortunately you cannot run a pump on a combi system, so apart from doing the above and checking that your stop cock is fully open (but turn it back one quarter turn, helps to stop it seizing) any service valves on the boiler mains feed open and perhaps no buildup of limescale (difficult one to check).

also make sure you buy a shower suitable for combi systems. i have a worcester bosch 28i combi recently installed and my shower is excellent. not a power shower by any means but perfectly adequate.

and £100 off your bill is a little bit low i'd say but not too much, if the leccy is now not having to supply and fit 45amp RCD and supply 10mm2 cable. but if he is rewiring the whole house anyway and has floorboards up already then the labour cost he allowed may be quite low. difficult to judge without seeing what's involved but £100 doesn't sound massively unreasonable.
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