BRASS AUTO BOTTLE AIR VENT 15MM COMPRESSION AIRVENT VALVE

BRASS AUTO BOTTLE AIR VENT 15MM COMPRESSION AIRVENT VALVE Description

All heating installers will dread calls from customers disturbed by noises from their heating system, indicating there is air in the system – especially if the report follows installation or servicing work. It is unsettling for householders, annoying for installers who have to revisit the installation, and can have other adverse effects: air can cause cold spots in radiators, reduce system efficiency and result in corrosion damage and consequently an expensive repair bill for the customer, who may blame the installer and blacklist them – and possibly tell their friends to do so too!

 A long-term problem of air continually getting into a system indicates a fault in the pipework layout. The aim when installing the system is to keep most of the pipework under pressure, not suction, to prevent air getting in. It is important to ensure the expansion vent pipe is not on the positive side of the pump by connecting it between the boiler and pump. The cylinder feed and radiator feeds should follow the pump, in turn.   

Inevitably, some air remains in a closed system following installation or repair work. It is easy to eliminate these short-term problems with an automatic air vent (AAV): a modest additional cost when a central heating system is installed, but is invaluable to ensure customer satisfaction and the likelihood of referrals, leading to more work!   

The AAV is a very simple and effective device, comprising a float inside a chamber. In the Honeywell EA122 (illustrated) water fills the chamber during normal operation, holding the float up to seal the vent at the top. If air enters the chamber, the float drops as the water level falls, allowing the air to escape through the vent. The float then rises again to re-seal the vent. This is repeated whenever air enters the AAV.  

The vacuum break on the bottom of the EA122 prevents an air lock forming and encourages air to be released from water.   When choosing a position for installation, pick an accessible area which can be seen and serviced easily, and in a point in the system where air is likely to collect. On a horizontal pipe run, provide a short upstand to ensure the air break is not in the water flow.  

It should always be installed in the positive pump pressure side of the system, where air is likely to be trapped, as it is possible air will be drawn in under negative pressure. A good static head is important: the greater the head, the more positively the valve will close.  

An AAV situated on a bend at the top of a vertical run works well on a gravity system but not on a pumped system. This is because the fast-moving air follows a route around the bend similar to that of a racing car and so bypasses the AAV. Air is removed most efficiently when the AAV is positioned at least 150mm from a bend.    

The EA122 incorporates an integral stop valve, so the seat can be cleaned without draining the system. The air vent can be fitted anywhere in the positive pressure side of the system where air is likely to be trapped. Air vents should always be fitted in an accessible area, which can be seen and serviced easily.