DIY Doctor UK DIY Forums

sorry guys but i'm a newbie to this forum.

i need to change my shower from an 9.5kw electric to a thermostatic mixer

we suffer low pressure or flow because we share a mains water feed from the road with the house next door but only have problems when next door turn on cold tap

if i put in a mixer shower with a pump from the hot water cylinder with equalising valve will this be the answer as most of the shower would be the hot water with some cold to regulate the temprature ? is the flow gonna be astly improved or only a little,also my friend who is a builder says the cold water mains pipe from road may be suffering from scale build up ?

thanks for any advice :D

The best way to do it so that its safe to use is to fix a storage tank in the roof of around 50 gall and feed the hot water to the cyld from that and also the cold feed to the shower if you can get enough head in the roof then you will not need a pump providing you use a low pressure shower mixer if you decide to use a pump you will need the high pressure unit its cheaper to have the tank higher than to pay for the pump etc
so you will have to chose which way is goin to be the best for your situation

The electric shower should be on the cold mains only which is why you are suffering loss of pressure if the mains is shared.

If you have a HW cylinder you will have a cold water storage tank in the roof.

Run SEPARATE supplies from the rest of your system for both hot and cold. Take hot from the cylinder via a Surrey (or similar flange) and cold from the CWST with a new connection to the tank. Take both supplies to a dual pump and pump both. You will then have a balanced supply. The pressure of both hot and cold will be the same (it being provided by the "head" betwen the top of the water level in the CSWT and the shower head). The pump will provd you with a good flow rate.

Your builder friend could well be correct but that should not affect your new shower if configured the way I've suggested. What it may affect is the rate at which the CWST is replenished as the water is used.

Make sure that the CSWT is of sufficient capacity to support this configuration remembering that it will be feeding both the hot (via the cylinder) and the cold (direct).

HTH

Cheers

thanks gasmick & rosebery for your help

i will stop trying to do things in a lazy diyer way and will follow rosebery's advice to run feeds from hwc and cold storage tank ! i reckon i will be able to do most stuff and if i put a plug on the pump shouldnt need any part p regs as pump will be in airing cupboard

will i lose performance over a pipe run of 4-5 metres using 25mm pipe ?

"will i lose performance over a pipe run of 4-5 metres using 25mm pipe."

No you'll be fine doing it even in 15mm but you could go up to 22mm if you really wanted to. As the pump does all the work 15 will be fine.

Where are you going to get 25mm copper tubing from?

Cheers

hi rosebery

yeah 25mm pipe is the new standard i have decided to set ! (you make one little typo and bam they get you !)

can i take the shower hot feed from the existing 22mm bath feed and then use a venturi shower linked to the cold water main, or do i definitly need a seperate feed fom hwc for shower.to use exisitng hot feed in bathroom would be miles easier and stop me having to remove a plaster board ceiling

always thinking of the lazey diy route


:lol:

If you have a low pressure system then the shower feeds must be independent and fed from the header tank and DHW cylinder.

I have seen one or two showers that allow connection to the mains cold and low pressure hot, but you cannot just use any shower. It has to be designed to work that way so check the brochures carefully.

You could always use conduit.... if you must use 25mm lol!!!

"yeah 25mm pipe is the new standard i have decided to set ! (you make one little typo and bam they get you !)"

LoL - thought you knew something I didn't. Spoilt it now!!!


"can i take the shower hot feed from the existing 22mm bath feed and then use a venturi shower linked to the cold water main, or do i definitly need a seperate feed fom hwc for shower.to use exisitng hot feed in bathroom would be miles easier"

Maybe but you need to have balanced supplies so the HW should come in a separate pipe from the HW cylinder via a flange and the CW from a separate takeoff (from the rest) at the CSWT. Cold from mains will always overwhelm hot from tank. You'll never get a satisfactory shower this way.


"and stop me having to remove a plaster board ceiling"

Are you sure you would have to do that? Removing the ceiling implies you want to get at the space above the ceiling. Can't you get to it from above rather than below?


"always thinking of the lazey diy route"

Which is inevitably always the most expensive route when you give up in frustration having spent hours at it and bought far more materials than you really needed and have to pay someone to sort it out for you.


Cheers