Dundee Wharf

Emptying Boiler

The air pocket in the Water Tank

These simple steps show you how to recreate the air-pocket in your water tank. First of all, we have to re-instate that following these steps is at your own risk, Dundee Wharf Management its agents and affiliates explicitly decline any responsibility.

If you decide to proceed, do it during the day once you do not need any hot water for the rest of the day (the hot water will be emptied). DO NOT LEAVE THIS HALFWAY OVERNIGHT!

The steps below are show for a MEGAFLO tank. We recommend that you refer to the MEGAFLO manufacturer instructions/manual or from your supplier. (Google search on MEGAFLO)

First of all let's check that the air pocket is gone:

Switch off electrical supply:

Switch off the electrical to the immersion heater.

Shut any incoming water into the flat:

If your flat is like the one described here, the tap for the main water pipe into your flat is above the water tank.

Close it tightly, you won't have any running water during this procedure.
close incoming water

Open kitchen hot water tap:

Open the Hot water tab in the kitchen, if the water water is running for less than 5-7 minutes, your water tank is filled with water and you should re-create the air pocket.
hot water running

Recreating the air pocket:

Keep Open the Hot water tab in the kitchen.

On the side of the water tank, there should be a hot water valve that can be open. When open, some air goes into the tank and some water runs from the open kitchen hot tap.

You need to put something in place in order to keep this valve open, the picture shows a small screwdriver (but you can maintain it open by hand if you want).

Let the tank fill up with air until the water stops running in the kitchen sink, this could take 30 minutes or more. Make sure that the main water is tightly closed.
screwdriver keep valve open
This example shows a Twist-top temperature and relief valve, like the figure below.
Twist-top temperature and relief valve
But you could have an older, Lever-type temperature and relief valve, like shown below, you just need to pull the lever to let some air in.
Lever-type temperature and relief valve

Back to normal:

Close the Hot water tab in the kitchen.

On the side of the water tank, remove whatever you put in the valve to keep it open. The valve should close by itself.

Re-open the main water tap in your flat.

The tank will now fill itself with water (cold). Let it finish before doing any "boost".
open water main

Once this is done, you can put another piece of kitchen towel through the overflow pipe opening and leave it overnight (as described here). If the paper is still wet the next morning, you definitely need to call a plumber, it is likely that you hot water valve is damaged and need replacing.

Switch the electrical supply to the immersion heater back on.