Condensing Boiler Bar Pressure

[Groupie]

Why does my Main HE condensing boiler losing bar pressure fairly often lately, and needs topping up.

[deggers316]

is there any water coming out of the overflow pipe from the boiler?

[Groupie]

Difficult to say it is directed to an outside down pipe. but i should think it would only be a small drip because of the ammont and the time span of refilling, about every other day.

[The Builder]

Here are the main suspects, Groupie.............

Small leak in the system somewhere (doesn't take much). Have a good look around, especially rad connections.

When the water heats up, it expands, and pressure goes up. To save the system from blowing up, an expansion vessel acts like a cushion to take up the extra pressure............ vessel diaphragm may be ruptured..... no cushioning, so the safety valve blows and the water escapes outside.

Safety valve (pressure relief valve) may be faulty, going off too soon.

Most likely by far though ............... pressure vessel has lost its charge of air pressure (on the other side of the diaphragm) ....... therefore diaphragm flops around with no cushioning effect.

The vessel should have a schrader valve sticking out of it (same as a tyre valve.) It just needs pumping up with a bicycle pump. Look in the manual for the pressure. Probably around 12 lbs/sq.inch. Heating engineers usually top this up at service time.

[Groupie]

Thx for that ,covers about everything