Potterton Promax 15 HE Installation And Servicing Instructions page 41

Dry-fire Lockout
Is there
NO
water in system
and pump on ?
YES
Is
YES
thermistor short
circuit ?
NO
Is
YES
flow switch short
circuit (G) ?
NO
Is
NO
flow switch
blocked ?
YES
Remove blockage.
Supplied By www.heating spares.co Tel. 0161 620 6677
Fill system and
switch pump on.
Replace thermistor.
Replace control PCB.
Replace flow switch.
15.0 Fault Finding
No Fan Run
Is
NO
thermistor between
0.5kΩ and 20kΩ ?
YES
Replace control PCB.
Replace flow
temperature
thermistor (red)
41