DIY Doctor UK DIY Forums

Help please! I have a problem with a Heritage Bath/Shower mixer tap purchased some 5 years ago. It seems to have an airlock on the hot water side, with the result that very little, if any, water comes out of the hot tap when the tap is turned on. The cold tap functions normally. A friend suggested I could free the airlock by blocking the spout, turning the cold tap fully on and gradually opening the hot tap. This works quite well for a while and then, after 3 or 4 turnings on of the hot tap, it reverts to form and no water comes out. What can be done to sort this problem once and for all?
Many thanks for any suggestions.

Gerry

Gerry Hayward,
Assuming you have a hot water cylinder supplied from a cold water tank the airlock is most probably in the pipe from the tank to the cylinder. If there is a long horizontal run coming out of the CWT see if you can find a joint to slacken to release the airlock.

Stoneyboy,
Thanks for your helpful reply. I have checked and the hot water cylinder is supplied from the cold water tank. Unfortunately there doesn't seem to be any joint that I can get to to slacken and release any airlock. Do you have any other suggestions? Thanks again.
Gerry

Do the same as you did before, by forcing the cold up the hot, but do it for about 30 secs at full bore if you can.

Quite why this has occurred is a little unclear. It might be worth checking the header tank outlet for an obstruction.

Try coupling a hosepipe between your hot and cold taps on the kitchen sink then open the hot tap followed by the cold one. This might be more successful at pushing the airlock back up to the cold water tank since the kitchen cold tap is likely to be at mains pressure. Alternatively, if you have a washing machine with hot & cold supplies, close off the two valves and couple them together with one of the two hoses and again open the hot valve followed by the cold one.

i had similar problem myself after draining the loft tank. , i drained the coldwater tank and cleared the airlock by sticking a hose pipe into the loft tank to hot water tank out let and using the pressure to force out the air. But you dont want to be doing this prior having a shower. My advice would be to fit a shower pump next to the hot water tank. i suspect that your shower is as normal on the same level as the tank it is the gravity of cold water entering the hot tank that causes the pressure to force out the hot water through the tap to the shower head. You turn off the shower and the water is falling back down the pipe back into the tank as the gravity fill of the loft to hot water tank is not sufficient to prevent air entering. Provided that the pipe next to the tank is not empty the pump should force out any air ahead of the water. The pump should be fitted as close to the tank as possible, if not and it is running after the airlock it will run dry and it will destroy itself very quickly. This is just a theory and i would get a plumber to take a look and comment on my theory what ever you do not act on it until you have as like i say its strictly theory.

Gerry Hayward,
None of the suggestions made by other forum members will clear an air lock in the cold pipe feeding the HWC.
In a previous thread it was suggested that a hose be connected to the mains feed to the cold water tank and this is then used to force water into the pipe which feeds the HWC. Its a neat way to solve this problem.
end

"None of the suggestions made by other forum members will clear an air lock in the cold pipe feeding the HWC."

But the OP said it was on the HOT feed!