A quick job this one – ever noticed the water pump starts occasionally for a few seconds without any demand for water from the taps? Maybe you can hear it during the night.

It’s usually a symptom of a failing valve or limescale affecting the smooth operation of the small 12mm valve attached to the boiler.

I’m not entirely certain if this is a “Pressure relief valve” to vent off excess boiler pressure or an “Automatic air intake valve” to aid the draining of the boiler and hot water system at drain-down.

Either way, you may also notice damp under the caravan close to where the clear plastic tube exits the floor of the van where water is escaping.

It’s all push-fit so easy to remove. Usually one can fix the old valve by soaking in vinegar which dissolves any limescale build-up.

In this instance after an annual vinegar soaking of the old valve, I decided to install a new one.

I’ll leave the comments open for a while so that if anyone knows the precise function of this valve, they can reply.