PREHEAT SATISFACTORY

Set Appliance State:

Ensure secondary heat exchanger is cool and there is a demand for preheat at start of test "d" in display
Hot Water Tap OFF

WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure

Mains Power On

Observation:

1. Allow preheat to run and complete pre heat cycle and return to standby mode indicated by a "0" in the display.
2. With no demand, allow boiler to stay in standby mode.
Does the preheat complete satisfactorily?

Note:
From cold, preheat cycle will take approximately 90 seconds to complete but this will depend on the starting temperature. If boiler is warm then a 't' will display; if boiler is cold then a 'd' may display. In this instance both are correct.
The boiler will fire periodically for a few seconds to maintain the preheat temperature. The average time period between firing is 90 minutes but varies with the surrounding ambient temperature.

Click here if H3 fault displays during preheat operation