No hot water, CH works fine

[Old Richard]

I recently replace my 3 way valve in the central heating / hot water system. I cannot get a flow of waterto the tank. With the system on, I can turn up the tank thermostat and can hear ( and feel hot water flowing into the tank, then after a fewminutes, the input pipe is cold again.
Help please

[stoneyboy]

Old Richard,
If you replaced like for like on the 3wv then you probably have an airlock in the system.
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