Water pressure too low, boiler cut out

[BelleCurve]

I have a vaillant boiler with cold water tank in the loft. Hot water stopped and the message on the boiler said water pressure too low. I've tried turning the valve in the loft but the water pressure indicator didn't move. Anything else I can try before I call the plumber?

if there is a pressure gauge on the boiler, it means that the boiler, the radiators, and the pipes that heat the cylinder are under pressure. This circuit is not connected to the tapwater. The tank in the loft is most likely to fill the hot water cylinder with fresh water which later comes out of the hot tap.

In this case, there will be a filling loop (probably) or valve under the boiler, enabling you to top up the pressure from the watermain, until the gauge shows correct. It is essential that this valve is kept closed at all times except when topping up the pressure, or the pressure will go too high and the pressure relief valve will open.

If you have not done it before, look for the boiler manual. If lost, you can download it from the makers website. When you have found out how to do it, tie a luggage label or similar on the filling valve to say what it is. It might possibly be blue. A filling loop is a pipe that is often covered in shiny stainless steel flexible braid, with a valve at each end. Both must be opened to fill, and both closed afterwards.

Thanks. I have the boiler manual which says "top up water pressure as instructed by your installer". I can't see any filling loop f similar under the boiler, will check again the loft this evening.

It won't be in the loft.

It will be close to the boiler, usually underneath.

Look for the incoming water supply pipe, usually 15mm copper, which will be the coldest of all the pipes.