Air locked HW system


1 Feb 2006
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United Kingdom
I have an on-going problem in my house with an airlock in the HW system. This most commonly happens when we get up in the morning. I have a downstairs toilet and I used to clear it by forcing cold mains water from the cold tap into the hot tap using a piece of hose. Since we got our toilet modernised we now have a mixer tap, which does not allow this.

I tried turning both taps on and blocking the outlet with my palm but this does not work. I have a contract with the gas board but each time they are called out all they do is clear the airlock leaving the root problem still there.

I got a plumber to connect the hot water to the cold under my sink via a valve and I can now use this to blow the airlock back but it's a PITA having to clear the cupboard out to get access to the vale. It seems to be worse when I have the HW stat turned up higher.

This happens on average every two or three weeks. Does anyone have any idea what could be causing this and how to fix it?
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Sorry! Wrong terminology, it's a conventional boiler. Vokera 12-48 RS Mynute.
There are alot of things this could be creating the problem,

Have you checked that your cold water storage cistern is refilling fast enough after you take a bath, for instance?
Yes, we have a HW cylinder and cold water storage tank

We have an electric shower and we seldom use the bath. I am also quite sure that the tank fills fast enough. We have good pressure.

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