My valiant turbo max combi boiler water pressure keeps going up to the max?

THE FILLING LOOP ON THIS MODEL IS UNDER THE BOILER AND REQUIRES A QUARTER TURN USING A SCREWDRIVER. CHECK THAT YOU HAVE THE PRESSURE GAUGE SET TO 1BAR THEN BE CERTAIN YOU HAVE TURNED OFF THE FILLING DEVICE.

THE PRESSURE GAUGE SHOULD STAY AT 1 WHEN THE BOILER IS COLD. IF THE PRESSURE DROPS THEN YOU HAVE A LEAK OR AIR IS ESCAPING THROUGH THE BOILER AIR VENT.
(IF YOUR PRESSURE RELEASE VALVE HAS BEEN LETTING BY THEN YOU MAY NEED TO REPLACE THIS)

IF THE PRESSURE GAUGE RISES OVER TIME WHEN THE BOILER IS NOT OPERATING THEN EITHER THE FILLING LOOP IS LETTING WATER THROUGH EVEN WHEN YOU THINK ITS SHUT OFF, OR THE HOT WATER PLATE TO PLATE HEAT EXCHANGER IS SPLIT INTERNALLY AND THE COLD MAINS PRESSURE IS FORCING ITS WAY THROUGH THE SPLIT AND INTO THE HEATING SYSTEM.

IF THE PRESSURE RISES ONLY WHEN THE BOILER IS RUNNING THEN THE EXPANSION VESSEL WILL BE AT FAULT. THESE CAN BE RECHARGED WITH AIR USING A FOOT PUMP BUT IF WATER COMES OUT OF THE AIR VALVE ON THE EXP. VESSEL THEN YOU NEED A NEW ONE. WE CAN SUPPLY SPARES.
CHRIS @ GAS SPARES LTD, 230 EASTERN ROAD, BRIGHTON
01273 673800

CHRIS GAS
July 2008

if it is doing it with the boiler off ,more often than not this is your filling loop letting by. even though you have it tightened up a little water getting by will do this. if it happens only when the boiler is in operation the expansion vessel could be at fault.

Kieran
July 2008