LOW WATER PRESSURE ?

MOST COMBINATION BOILERS OR SEALED SYSTEM BOILERS REQUIRE A PRESSURE OF 1 -1.5 BAR TO OPERATE CORRECTLY. IF YOUR BOILER HAS LOW WATER PRESSURE THEN IT MAY WELL RESULT IN EITHER POOR PERFORMANCE OR IT MAY NOT WORK AT ALL. OPERATING A BOILER ON LOW PRESSURE CAN CAUSE THE BOILER TO OVERHEAT OR CUT OUT BEFORE IT REACHES THE CORRECT TEMPERATURE. MOST BOILERS WILL HAVE A GAUGE WHICH INDICATES THE ACTUAL PRESSURE, CHECK YOUR GAUGE AND SEE WHAT THE PRESSURE IS, A NEEDLE WITH A BAR GAUGE SHOULD INDICATE THE CURRENT PRESSURE. IF IT IS BELOW 1 BAR, YOU SHOULD TOP UP THE PRESSURE VIA THE FILLING LOOP, IF YOU DO NOT KNOW HOW TO DO THIS THEN CALL A EXPERT (BE WARNED THAT IF YOU OVERPRESSURE THE BOILER YOU WILL BLOW THE SAFETY VALVE, WHICH WILL THEN NEED REPLACING).

THERE ARE VARIOUS REASONS FOR LOW PRESSURE, IT IS NORMAL TO HAVE TO TOP UP THE PRESSURE MAYBE ONCE PER YEAR, IF IT IS MORE THAN THIS THEN THERE IS A LEAK ON THE SYSTEM WHICH WILL NEED INVESTIGATING. THE FIRST THING IS TO CHECK THE SAFETY DISCHARGE PIPE, IF IT IS LEAKING THEN IT WILL NEED TO BE REPLACED, BUT BEFORE YOU DO THIS, THE EXPANSION VESSEL MUST BE CHECKED FOR CORRECT OPERATION.  ALL SEALED SYSTEMS MUST HAVE A EXPANSION  VESSEL, WHICH ALLOWS THE WATER TO EXPAND INTO WITHOUT INCREASING PRESSURE IN THE SYSTEM. YOU WILL NOTICE THAT WHEN THE BOILER IS COLD THE PRESSURE IS SLIGHTLY LOWER THAN WHEN IT IS HOT. IF WHEN THE HEATING IS ON THE PRESSURE KEEPS GOING UP AND REACHES THE RED WARNING NEEDLE OR AREA, THEN THE SAFETY VALVE WILL OPEN TO REDUCE THE PRESSURE, ONCE THE SAFETY VALVE OPENS IT RARELY CLOSES AGAIN, WHICH MEANS THAT THE PRESSURE WILL DROP AND YOU WILL HAVE TO CONSTANTLY TOP UP THE PRESSURE. IF YOU KEEP DOING THIS YOU WILL CREATE MORE PROBLEMS, AS THE AIR THAT IS DRAWN IN WILL CREATE IRON OXIDE SLUDGE, AND CAN CAUSE PIN HOLING OF RADIATORS AND ALL SORTS OF PROBLEMS, SO YOU SHOULD GET THE PROBLEM RECTIFIED AS SOON AS POSSIBLE, OR YOU MAY HAVE TO REPLACE THE ENTIRE BOILER.

OBVIOUSLY IF THE PRESSURE GOES UP TOO MUCH, THEN THE EXPANSION VESSEL IS FAULTY, THE VESSEL IS FITTED WITH A RUBBER DIAPHRAGM WHICH CAN SPLIT, WHICH THEN RESULTS IN THE CENTRAL HEATING WATER MIXING WITH THE GAS IN THE EXPANSION VESSEL, RENDERING THE VESSEL USELESS.

I WOULD SAY THAT OVER 60% OF BOILERS HAVE EXPANSION VESSELS FITTED IN SUCH A WAY THAT YOU CANNOT CHANGE THEM WITHOUT TAKING THE BOILER OFF THE WALL! WHICH IS CRAZY. WE CAN INSTALL SEPARATE VESSELS ON THE SYSTEM IF REQUIRED.

OTHER THINGS TO LOOK FOR ARE LEAKS ON THE BOILER, BOTH INSIDE AND ON PIPEWORK, LEAKING AUTO AIR VALVES, LEAKS ON RADIATORS AND VALVES AND LEAKS ON PIPES UNDER FLOORS.

THE LAST ONE IS THE MOST DIFFICULT, AS YOU WILL NOT BE ABLE TO SEE IT, YOU ONLY NEED A VERY SMALL LEAK TO DROP THE PRESSURE ON THESE SYSTEMS, AND IT CAN GO UN-NOTICED IF IT IS UNDER THE FLOOR. IT IS POSSIBLE TO PUMP IN A CHEMICAL WHICH WILL AUTOMATICALLY SEAL THE LEAK, BUT THIS WILL ONLY WORK IF IT IS A SMALL LEAK, AND CAN TAKE UP TO 6 WEEKS TO WORK.  WE HAVE SEEN INSTALLATIONS WHERE THE PIPEWORK IS BURIED IN CONCRETE, IF THIS IS COPPER AND IS NOT PROTECTED THEN THE LIME CONTENT OF THE CONCRETE WILL CORRODE THE COPPER, ALSO IF NO ALLOWANCE HAS BEEN MADE FOR THERMAL MOVEMENT THEN THIS CAN CAUSE STRESS ON JOINTS WHICH CAN ALSO LEAK, SO THIS PRACTICE SHOULD BE AVOIDED, BUT IF YOU ALREADY HAVE THIS TYPE OF SYSTEM THEN YOU MAY HAVE BIG PROBLEMS, SOMETIMES IT MAY HAVE TO BE RE-RUN COMPLETELY.