Water Pressure Query

[jaqatron]

Hi all,

I'm looking for some advice, I've just moved into a flat but whenever we run the hot water the pressure drops off severely. The cold water is totally fine and I've tried bleeding the radiators to improve it but it didn't work. Does anyone have any DIY tips I can try before having to get a professional involved?

Thanks
Jaq

 

[conny]

Your hot water for washing/bathing etc is not connected to the water in your radiators, so bleeding them will have no effect.
What is the pressure like when you first turn a tap on and how long does it take to drop off?
Is it just the one hot tap or all the hot ones?

 

[terryplumb]

What pressure drops ?
The water coming from Taps ,or boiler pressure ?
What provides your hot water ,combi boiler ,hot water cylinder ...something else ?

 

[jaqatron]

Hi Terry,

So it's occurring if we use either the taps or the shower and when they are running it drops on the water pressure gauge to below the operating standard.

It's a protomax combi HE boiler.

Thanks

 

[terryplumb]

So it's the pressure gauge on the boiler that drops ,and the water pressure from taps and shower is fine ,is this so ?
If it is ,does pressure on boiler gauge return to what it was when taps/ shower are turned off ?

 

[jaqatron]

Hi Terry,

It's both the water pressure from the taps and shower and the pressure from the boiler that drops during use.

Once we turn off the taps or shower the boiler pressure returns to normal.

 

[jaqatron]

Your hot water for washing/bathing etc is not connected to the water in your radiators, so bleeding them will have no effect.
What is the pressure like when you first turn a tap on and how long does it take to drop off?
Is it just the one hot tap or all the hot ones?

Hi Conny sorry I never noticed your reply. When the tap is first turned on the pressure is fine but once it heats up the pressure just drops.

 

[terryplumb]

You are going to need a plumber to attend to establish what's causing the water pressure at tap/ shower to drop off when in use. The gauge on the boiler registers the pressure in the sealed central heating system ,not the tap water pressure.

 

[jaqatron]

Thanks, that's what I suspected but I thought I'd check first.

 

[oldbutnotdead]

It sounds as if the filling loop to your heating system has been left open.
Experiment; turn off cold water at main stoptap, run cold tap, watch boiler pressure (it should drop to near zero as the cold water in the pipes runs out).
Fix- find the filling loop, make sure both taps are OFF. Turn cold water back on- if boiler pressure increases immediately then the filling loop taps are passing water and need replacing as does the backcheck valve that should be in the filling loop.