DIY Doctor

No Hot water pressure

Postby Trevalex » Sat Jan 12, 2008 12:19 pm


A problem has developed in my hot water system over the last few months. I think its an air lock somewhere..

System set-up:
Firstly I have central heating fed from a central boiler in my estate, there is nothing wrong with the heating it all works fine.
From reading this site ([url][/url]) I understand I have a indirect cylinder system.
The cold water is fed from a large galvanized tank, and the cold water is heated by a coil in the tank, which is fed by the main central heating).

Recently I noticed my cold water pressure has gone up significantly (which has coincided with Thames water replacing the water main, I am in London, but this is prob not related) and my hot now runs to a trickle, and last night it was just not pulling through at all even at the lowest point.

On my tank where my cold feed should be, this pipe is red hot, is this a problem? I would have expected it to be cold, sorry I have never really checked before.
The pipe at the top of the tank is also hot.

A mate suggested find the lowest point and using the water pressure from the cold connect a hose pipe to the hot and turn the taps on.
I have mixer taps on both my lowest point taps, so I just blocked the tap and opened up both taps, this seemed to push water back round the hot water system, and for a minute I had heated water again.

Then the pressure goes again.
I am not sure how long to do this for, maybe someone could clarify?

What's the best way to release this air lock/bubble?
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Simply Build It

Postby Trevalex » Sat Jan 12, 2008 2:40 pm


I was doing roughly the right thing.

I ended up using the bath taps (I have an up-side down house, bath down kitchen up).

The bath tap was a mixer with shower attachment I took off the shower hose and this gave a tidy hole which I blocked with my thumb. I then pulled the plunger to allow the mixer to go into tap mode. Opened the hot tap and opened the cold...

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Joined: Sat Jan 12, 2008 12:01 pm

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