Increasing pressure in household cold water system

Noopz

Noopz

Noopz

Associate
Joined
27 Sep 2003
Posts
79
Hi guys.

THe water system in our house is as follows:

Combi boiler so mains pressure to all hot water outlets plus cold water in kitchen.

Bathroom cold water systems are fed from the loft cold water tank.

SO, in our bath & shower, we get more hot water pressure than cold water pressure, which makes it fairly difficult to get the water temp right for us. ( i also need to change the washer on the hot water bath tap). The previous home ownders also had 15mm piping going to the bath instead of the 22mm that i would have fitted.

Anyway, i was considering, is there a fairly inexpensive way to increase the pressure coming from the cold tank to the bathroom, not too much, but just enough to get it slightly more than mains pressure. Some sort of low pressure pump i would imagine.

Thanks guys,

Mal :)
 
Surely a larger pipe's going to decrease pressure? Pressure being Force/Area and all that.

Would probably increase your flow rate though.
 
csmager said:
Surely a larger pipe's going to decrease pressure? Pressure being Force/Area and all that.

Would probably increase your flow rate though.
Click to expand...
yup increased flow, which would be more what he wants, I think.
Problem with adding a pump between the header in the loft and the bathroom tap is that if the pump empties the tank faster than the main can refill it.....well i'm sure you can see. This would require a bigger header etc etc.
 
You will get increased flow if you change the pipe size and pressure loss in the pipe will drop and maybe give more pressure at the end. Thing is it might not, as it all depends on the height of the tank above the fitting. The pressure coming out of the cold system is a fixed figure due to the mavity etc from the water in the tank to the fitting.

Easiest way would be to reduce the hot water pressure at the fittings as you don't tend to normally put a pump on the feed from a cold tank. You could buy a local booster pump for the pipework in bathroom but would be a more pricey option compared to other ways as wiring, fitting etc adds up. As has been said above it could empty the tank quicker and pump dry. It might be easier reducing the pressure of the hot water at the bath/shower and cheaper than pump option.

To reduce the pressure of the hot water to the bath, a pressure reducing valve fitted in the hot water pipework to the bath/shower is the cheapest option. You will need to balance the pressure reduction so you get the balance you want. This all depends on your system and best person who will know for sure would be a plumber.

SCM
 
Last edited:
malfunkshun said:
cheapest way would be to change that 15mm pipe, but not necessarily the easiest.
Click to expand...

Pipe size will change the flow rate - the pressure will remain the same.

Why not just run mains cold to the bathroom and scrap the tank in the loft completely?
 
I was just about to suggest the same, why bother with a cold water tank at all, just use mains pressure throughout the house.

The only reason these days that I can think off to have a cold water tank, is as a seperate feed to an electric shower, so you don't get pressure drops and temperature fluctuations if someone turns another tap on.
 
Perplexed said:
Pipe size will change the flow rate - the pressure will remain the same.

Why not just run mains cold to the bathroom and scrap the tank in the loft completely?
Click to expand...


Yup, use the mains pressure, not the header tank. :)
 
You can buy pumps that go inline with the water pipe. If it's struggling to get enough cold out of the tank then a pump will suck it out and give you the shower you want.

The reasons you won't be getting enough water is either the tank isn't high enough to give you enough pressure (because pressure = h*rho*g where h is the height, rho is the water density and g is mavity so the higher the tank the higher the pressure) or because the tiny pipes are limiting the flow. I reckon it's the small pipes personally and to save stripping it all out I'd just fit a pump. I think Homebase and B&Q sell them if you don't know a plumbing place
 
Can't you just reduce the heat output from the combi boiler, making your hot water come out a little cooler?
 
You must log in or register to reply here.
Back
Top Bottom