What shower pump do I need, what kind of water system?!

[RyanHughes]

Hi guys,

Newbie here, and a complete noob when it comes to plumbing.

First question is; what kind of plumbing system do we have? We have a hot water tank in the airing cupboard in an upstairs bedroom, and I think some kind of hot water tank in the loft. Pretty sure the cold runs directly off of the stop cock under the sink in the kitchen.

We have good water pressure at all taps in the house, including the hot water. However, when we try using the mixer tap shower head in the bathroom, hot water comes out slowly (but fast out of the tap), and cold comes out very fast through the shower head or tap. If we try mixing hot and cold, the cold completely cuts off the hot water coming out of the shower head. Hence we can only have scalding hot dribbling showers, or blasting freezing cold showers. Not fun!

Looking to install a pump under the bath to fit a shower to (probably just a mixer tap shower), but wondered what kind of pump I need? Negative or positive, and any recommendations on what bar I need?

Thanks in advance guys!

Cheers,

Ryan

 

[Madrab]

Sounds like you have gravity fed hot water (cold supply cistern in loft feeding a vented hot water cylinder in the bedroom) with mains cold water. If you can get hot water at the shower head at maximum height without the cold on at the moment then you should get away with a normal, positive head, pump.
The issue you have at the moment is you have mains pressure cold water feeding the shower with gravity hot water and that pressure imbalance is why the cold stops the hot.
Ideally you want to have a dedicated cold feed from the cold tank up in the loft and a dedicated hot from the cylinder so the pressures are balanced and run that through a twin impeller pump. Stuart Turner pumps are my recommended choice and if affordable, with brass ended impellers.
http://www.stuart-turner.co.uk/products/monsoon/s15-bar-twin/

 

[Galoka]

Well you have stored hot water, by the sounds of it not at mains pressure (mostly likely a domed top copper cylinder, covered with foam insulation, or an jacket if old). There will be a cold water cistern in the loft, feeding this tank, and possibly some of the cold taps or toilets (you can tell which,by turning of mains stopcock and seeing if any of the cold draw off still work)

However, the behaviour of the bath/shower mixer suggests that the cold there is direct from the mains. It is at much higher pressure than the hot, and that is why is stops the HW coming through.and why you get much better cold shower performance than just the hot.

If so, You can fit a, single impeller pump on hot feed.

Negative or positive head? You need enough flow to trigger the pump. Check your flow from the shower head at showering height. if it is at least 1L/min (not a lot) then you can use a positive head pump. 1.5- 2 bar would suffice.

you might need to do a bit of re-plumbing as the hot feed for the pump should be on it's own feed from the HW tank taken in a suitable manner. have look on Salamander's or Stuart turner's websites for installation instructions, as that will give you an idea of what is required.


I don't know how balanced the pressures need to be. If the mains is a lot higher than the pump you might need to fit a pressure reducing valve in the cold feed on the bath

 

[RyanHughes]

Brilliant, thanks for the informative replies guys, very helpful!

Cheers,

Ryan