Bath water pressure

Hi

I hope you can help me with a problem and suggest a solution.

I live in a flat the CH/HW system is open vented with the cold water
tank (about 15gallons, fairly small) directly above the hot water cylinder
which is of standard size, both are in the airing cupboard.

The cold water supply to the bathroom is at mains pressure to the WC,
basin and bath. The hot water supply to the basin and bath comes from
the hot water cylinder but because of the low height of the cold water
tank the hot water pressure is very low, not really
sufficient to get a strong spray from the bath shower mixer. Although the
cold water is ok because its at mains pressure the hot water pressure is
poor.

I am puzzled at how to achive a good even hot and cold water pressure
to the bath shower mixer. Should I:-

1. Leave the cold feed at mains pressure and just pump the hot water or is this wrong as the hot and cold suplly would be at two different pressures. Do I need a Surrey flange with this arrangement.
If this is correct can you suggest a pump that would do the job.

2. Supply the bath cold water from the cold water tank and pump both
the hot and cold water supply to the bathroom. If I do this am I at risk of the cold water tank emptying.

Thanks you for your help...

I would say to pump both hot & cold - if your CWT is about 50gallons (227 Litres) then you should be fine.

We use a Stuart Turner Monsoon 2bar twin impeller, negative head pump on one of our products, where the water board wont allow unvented cylinders in flats.

The pump delivers about 18l/minute mixed water - plenty for a shower, and even if there were no water refilling the cold tank, this would be ufficient for up to 12.5 mins in the shower. Depending on your cold mauins flow rate, and the type of ballvalve, you should be making it up as you draw it off.

The piping of the ht water supply from the tank is crucial so as not to draw air into the system, but the stuart Turner website has some information to download (IIRC) and thier technical helpline guys are very helpful if you need to call them.

But the CWT is a tiddler.
The thing will have to be filling quicker than it empties or there will be trubble!
Often its possible to change or modify the ball valve so the tank fills quickly.