Alpha Combi Boiler pressure issues

[Liam_Davis]

Hey people, i have a problem with my Alpha combi boiler, when the boiler is workinh the pressure is maxed out and water starts to drip from somewhere in the boiler, when the boiler is completely cool the pressure doesnt go nowhere near as low as the green preferred pressure line, i was told to release pressure by bleeding radiators which i did this morning which worked fine the pressure was normal now, when i go home at lunch the pressure had gone up high again even though the boiler hadnt been used, now im no professional but common sense tells me that something is letting the tank constantly fill itself up

Any help on this topic would be very much appreciated

Thanks

[heathfield]

There are reports of the blue filling loop tap knobs breaking on Alpha combi boilers, so you turn the knob, but nothing is happening. Could it be that the tap is stuck in the slightly 'on' position? Remove the knob and use a screwdriver on the tap shaft to check. Another way to check whether the tap is faulty would be to reduce the pressure to normal first thing in the morning, then turn off the house water main and see if there's been any change when you return at lunchtime. If there hasn't, then it has to be the tap that's at fault.

[LCDMAN]

Your expansion chamber has probably failed - this mirrors the symptoms you describe, massively over pressure when hot and ok when cold. The expansion chamber is a pressurized rubber bladder filled with air (in the boiler) - it takes up the "slack" as hot water expands o keep the system pressure constant! If it fails then it fills with water and there is nowhere for the hot water to expand to, thus increasing the pressure till it max's out.

You can either replace it (major boiler surgery!) or get an external one.

[LCDMAN]

Sorry, forgot to start with " If it isn't the filling loop leaking then......"

[johnk]

Try HFs idea first, cheap and easy to do.