System Component Testing

Boiler System Component Testing – for Heating Engineers

Air Pressure Switches (Testing)

Testing the boilers Air Pressure Switch, is always an indicator that other problems may exist. This article helps to diagnose the Air Pressure Switch issues on a boiler.

Air Pressure Switches (General)

Air pressure switches (operating @ approx. 0.5 – 4 m/bar pressures) See also: How to test your Air Pressure Switch with a multimeter Reasons an air pressure switch will fail to start: Loose electrical connections Kinked or split rubber h...


Boiler Fault Finding - Thermostats - See also: Cylinder Thermostats Room Thermostats Thermostats Overheat Cut out Thermostats Liquid Expansion Electrical Safety Checks - Resistance to Earth Top Tips for the Heating Engineer...


What is a thermistor used for in a combi boiler

Boiler Fans

Reasons a fan will fail to start No 240V supplying (L) & (N) terminals Burnt out motor windings Worn out bearings Air rotor jammed (on fan casing) impeller heavy with foreign matter accumulation Faulty fan speed control resistor (if fitted) ...

Circulating Pumps

A failure of the circulating pump can cause a number of problems, such as reduced heating and hot water performance, and can result in the boiler shutting down.