1. Principle of Air Pressure Switch:
In the initial state, the air pressure switch of the water heater should be closed. When the water tap is opened, the microswitch of the water valve activates, sending a signal to the controller. The controller then sends a signal to the fan, causing it to run. Simultaneously, it sends a signal to the solenoid valve to open the gas valve. Once the fan is running, it creates negative pressure, opening the air pressure switches. Upon receiving this open-circuit signal, the controller considers the fan to be operating normally and sends a signal to the pulse igniter, which ignites the gas.
2. Common Faults of Hot Water Heater Pressure Switch:
As can be seen, the air pressure switch should normally be closed and open during operation. If the air pressure switch remains closed, opening the water valve will allow the gas solenoid valve to open, but because the air pressure switch is constantly closed, the controller will interpret this as a malfunction in the fan and will not send a signal to the pulse igniter, resulting in an alarm. If the air pressure switches remain open, opening the water valve will cause the controller to interpret this as a malfunction, preventing the gas valve from opening and triggering an alarm. If the water heater fails to ignite, there are two possibilities: a faulty pulse igniter or a faulty water heater pressure switch. Using this principle, if the water heater pressure switch is faulty, you can try this to get the water heater working: First, short-circuit the two wires of the water heater pressure switch. After opening the water valve, disconnect the two wires. This should allow ignition. After ignition, the water heater will work normally regardless of whether the two wires of the water heater pressure switch are open or closed. This way, the water heater can still operate even if the water heater pressure switch is faulty. Most faults with the air pressure switch are due to reduced sensitivity; that is, although there is air pressure, it is insufficient to activate the switch, thus preventing ignition.
3. Adjusting the hot water heater pressure switch:
Manufacturers require special tools for replacing the water heater pressure switch. We have developed a simple and practical adjustment method, and this method is very sensitive.
When the knob for the water heater pressure switch replacement is fully turned out and removed, the switch is open. With the two probes of a multimeter connected to the two pins of the switch, the multimeter resistance will be infinite. Then, slowly turn the knob clockwise until the water heater pressure switch replacement just closes the circuit, i.e., the multimeter resistance is close to the circuit. Stop turning the knob. At this point, the pressure switch is in its most sensitive mode, meaning that even a slight negative pressure generated by the fan will activate the pressure switch, generating an open-circuit signal, which in turn sends an ignition signal to the igniter. This adjustment may require repeated adjustments for greater accuracy and more sensitive operation of the water heater pressure switch replacement.
