Plumbing info please - shower pump

[Billjratt]

not boaty -but could be...Plumbers -one pace forward.
We have a shower pump : one motor-two impellors, with demand switches (like the one on the boat).
I need to boost the hot water pressure in the kitchen, to balance the pressure to the rising main.
if I tap off the hot feed to the shower, the pump will run but the cold feed will be stalled.
Will this be a problem either to the cold impellor or the motor, or, will the vanes of the stalled impellor just fold in and ride over the static water?
In a word - can I feed the kitchen (including white goods)) from the shower pump?
Your experienced replies are eagerly anticpated.

 

[daveyw]

Think you can get pumps with one impellor but not sure they do hot water http://www.plumbworld.co.uk/single-impeller-shower-pumps-1647-0000


Oh........

"Note: These pumps should not be used for:
- Supply of hot and cold water services to a common mixer.
- Supply of pumped hot water service to a common mixer valve where the cold supply is mains fed.
- Pumping to multiple outlets."

 

[saltylegs]

sounds like your cold is supplied via the mains and hot via a header tank.
if you are using through a mixer tap or mixer valve then both should be from the same source.
the simplest way would be to supply the cold from the same header tank as your hot.
1 do you have a header tank in the roof space?
2 do you have a combi boiler?
3 why do you think you need to boost the pressure? could it be a lack of flow instead perhaps due to a small diameter pipe?

 

[rogerthebodger]

You could fit a pressure reducing valve in the cold water feed to reduce the cold water pressure or fit a pressure switch in your hot water pipe after the pump to switch off the pump once required pressure in the hot water is reached.

 

[Billjratt]

I just asked IF it would work, and didn't say why it was needed.
The kitchen is fed from the rising main because that is fresh water for the cold tap - drinking, cooking etc.(header tank is stale, could have sludge and worse at the bottom...)
the tap is a mixer, and has a trigger operated flexible hose which works by using a bypass valve (like a Karcher) which , of course, needes pressure to operate. At the moment, it only skooshes when the cold is on.
There are non return valves required in both feeds to the tap to prevent water from the header tank getting back into the common rising main.
The tap requires pressure in order to operate the bypass valve.
There is no combi boiler, no gas in the house.
The pump 'appears' to be an impellor type ( I haven't stripped it yet) as it runs quieter than the one on the boat, which "grunts" a bit and is an eccentric driven diaphragm pump.
The bit I'm not sure about, is how the demand switches work : - easy on the boat, there is pressure mantained by the pump non-return valves and the accumulator, but how does it work on the shower pump, with no accumulator and just the impellor to stop backflow, are there extra valves built- in?
There is a drawing on the wickes site showing a set up similar to the one I require, but has anyone actually done it and is prepared to endorse it?

http://www.wickes.co.uk/pcat/46showerpumps Diagram "C"

- As usual, thanks in anticipation.

 

[rogerthebodger]

That pump switched on by using a flow switch not a pressure switch so when under normal operation you open the shower head the pressure in the header tank will cause a flow through the pump causing the flow switch to operate thus switching the pump on to increase the flow. When shower head closed flow stops pump turns off.

In you proposed setup are you going to only pump the hot water as this pump seems to be a double pump one for hot one for cold but is says inlet pressure to both must be the same (from the same sauce).

Not don it as we do not use shower boost pumps. Some housed do have a pressure using a bore hold pump but this is not your setup.

Don't see why it should not work if you use both sides of the pump to pump the hot water only.

 

[JohnTH]

Good morning Billjratt.

No, I have not tried the layout in diagram “C” but can see that it should work.

Having had a similar problem (not enough hot water pressure) recently my solution was to fit a different hot water cylinder. The new item features a S/S tank within a tank. Cold water from the rising main is heated in the S/S tank (fed to the domestic hot system) by the (central heating) water in the outer tank that is heated by the boiler.

I now have hot water at the same pressure as the cold from the rising main.

An additional plus point is no head tank collecting sludge.

Looks like we use the same water supply company !

73s de

Johnth

 

[Billjratt]

Hi JohnTH, We could indeed use the same water supply, as I am in Prestwick not too far from you. (Are you "donro"?)
Your solution is ideal, but as we don't have central heating, and only a small immersion heated tank, I guess we're stuck with the pump.
Thanks, Rogershaw for that flow sensor info, now everything makes sense.
I think I'll go ahead and give it a bash, since it's just a case of teeing in plastic pipe.
If I don't come back all grumpy, you'll know it worked, and the soup-dragon will be skooshing all over the place.
Thanks again guys.

 

[JohnTH]

Good morning Billjratt

Yes I am indeed Donrho and just up the road from you.

Good to hear that you have found a solution for your hot water. The tank that I have installed also works from the electricity when the central heating has been switched off.

73s de

Johnth

 

[Silent Lady]

Tried that

Tried that years ago on an upstairs hot tap. Sounded like a good idea but you need a flow to kick the pump in. Had problems with the pump staying on and eventually gave up and put a bigger header tank in . More water more force going down the pipe . Pump was similar to a CH pump with an inline flow valve .

 

[pete]

As IAN13 says if there is no flow from the hot tap the flow switch will not work. Fitting a larger tank will not give you any more pressure unless it is fitted higher (giving you more head of water).
Your cheapest solution is to change the tap but fitting an unvented hot water cylinder has lots going for it providing you have good cold water pressure and flow but they are not cheap.
pete

 

[JohnTH]

Keep an eye on E Bay for unvented tanks.

Mine was much less than half price although I did have to go and get it.

73s de

Johnth