Water Pressure Meter

[bobloes]

I do occasional plumbing for my kids and there is the usual problem (so I believe) of different pressure for hot and cold water fed to the shower. I would like to measure the pressure of the two feeds but buying a water pressure meter would be a waste of money given it may never be used again. Can I use/adapt my tyre pressure gauge for this purpose? Or any other suggestions? Cheers.

 

[gasafengineer]

You could always use your thumb.

 

[D_Hailsham]

I do occasional plumbing for my kids and there is the usual problem (so I believe) of different pressure for hot and cold water fed to the shower.

Where do the hot and cold supplies come from?

Is it a combi boiler, so both hot and cold come straight off the mains? or,

Is there a hot water cylinder, with a cold water storage tank in the loft feeding the cylinder and the cold taps?

Whichever system is used, the hot and cold pressures should be the same.

The only time there could be a pressure difference is if the cold water comes straight off the mains, but the hot water comes from a cylinder fed from a storage tank in the loft.

 

[xr4x4]

I do occasional plumbing for my kids and there is the usual problem (so I believe) of different pressure for hot and cold water fed to the shower. I would like to measure the pressure of the two feeds but buying a water pressure meter would be a waste of money given it may never be used again. Can I use/adapt my tyre pressure gauge for this purpose? Or any other suggestions? Cheers.

They are about £8!

 

[bobloes]

D-Hailsham. It is a combi and the cold is mains pressure so I agree the pressures should be the same. However having taken flow rate measurements there is definitely something odd.

If you are interested the flow rates through their normal bath/shower mixer unit are as follows:

6mm shower hose

Bath Cold 21L/min
Hot 8L/min

Shower Cold 5.4L/min
Hot 6.4L/min

Kitchen Sink Cold 10.5L/min
Hot 7L/min

Condensing Combi boiler Potterton Gold Combi 24 HE A

 

[dreadnoughtheating]

For sure most combi's do have a flow restrictor factory fitted, and some also have a filter on the cold-water inlet, perhaps this could be checked?

Also, check that inlet tap to appliance is fully open, also that any isolation/service valves under bath etc are fully open, no 'kinks' in plastic pipework/ flexi-hoses etc.

DH

 

[Agile]

The standing pressure will be constant.

The flow rate will depend on the resistance of that circuit.

The shower may be a thermostatic om may just have an intentional higher resistance on the cold flow.

So what actually is your problem?

Tony

 

[bobloes]

The problem is that when switched to shower to get a temperature which is usable the cold water is fully open and the hot water control is open the merest touch. Hence the flow is not particualary good. The hot water is set at 65 degrees and yes I have told her to turn it back to 50 when she wants to shower but kids, what can I say. However if you look at the flow rates on shower position it is easy to understand why. I am assuming it is to do with pressure through a mixer unit and a 6mm hose hence the original question. It is a simple pull up knob on the mixer unit with no thermostatic control. Cheers

 

[gasafengineer]

I would take a bet cold water is fed from cold water storage cistern.....................open basin taps & hold finger or thumb over spout , cold tap should be pretty easy to 'plug' as opposed to hot tap.............simple but effective.

 

[bobloes]

gasafengineer Now I understand your earlier post. I thought you were just being sarcastic because I am tight fisted. I am not in London but I will get her to check. It is a block of flats so I am expecting it to be mains. Cheers

 

[gasafengineer]

I thought you were just being sarcastic because I am tight fisted.

.....................always a little something there , sarcastic , never.................. ................

 

[bobloes]

Yep Discovered that even though it is a block of flats in London sure enough there is a header tank. So is there any way of overcoming this pressure difference. I think I have heard of non-return valves. The head is about 10 metres so I am guessing the cold water is about 1 bar pressure.