DHW PREHEAT OPERATION

Set Appliance State:

Ensure there is a demand for preheat, boiler cool

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

Mains Power On

Observation:

If required cancel purge cycle & reset boiler.
Activate DHW Preheat function, turn DHW temperature control to the preheat symbol then back to the required temperature setting. The activation of this function is indicated on display with the P icon, a blinking P icon indicates preheat is running (see note).
Does the boiler perform pre-heat function correctly?

Preheat function

Preheat function active

Preheat function running

Note.
1. It can take several attempts to activate the preheat function.
2. When the DHW pre-heat function is enabled, the appliance will light periodically to maintain the temperature of the DHW heat exchanger. When the DHW thermistor and the primary thermistor fall below 35°C and 55°C respectively, the boiler will fire on minimum +25% power until the primary thermistor exceeds 55°C. Thereafter the pump will over-run for a period of 30-seconds.
3. When preheat is active LED next to tap symbol will also illuminate.