Just recently when I turn on shower (combi boiler system) I get water hammer for a short while. I have found it will stop/almost stop if I turn on sink tap. This morning during a shower the water started to get cold as well. Would appeciateany guidance. Trevor
Also, this does sound like you have an air lock somewhere in the system possibly. Although the following project page is mainly focused on air locks in taps it may be worth looking at the following project page also: https://www.diydoctor.org.uk/projects/curingairlock.htm
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