Fault On D.h.w - Savio 20/1 MFS User Manual

Fault finding
7.10 Fault on d.h.w. --- c.h. switching
Initial conditions:
--- the function switch is in position.
--- the thermostat or timer is calling for heat ref. 23.
--- The lever on the 3---way valve is set to " automatic" ;
ref. 24.
--- There is a faulty sensor or float in
the flow switch on the d.h.w. cir-
cuit. ref. 29
--- The float is jammed.
NO
When d.h.w. is withdrawn, do
the contacts close in the flow
switch? ref. 28
YES
--- The electronic regulation p.c.b. is faulty.
--- The electronic regulation p.c.b. is faulty.
NO
When d.h.w. is not being
withdrawn, do the contacts
close in the d.h.w. flow
switch? ref. 28
YES
--- There is a faulty sensor or float in the
d.h.w. flow switch ref. 29
46
Start
The appliance operates in the
c.h. mode only, and not in the
d.h.w. mode.
When d.h.w. is with-
drawn, does the burner
shut off immediately?
NO
When d.h.w. is with-
drawn, is power fed to
YES
the 3--- way valve?
ref. 27
NO
--- The 3--- way valve is blocked
in the c.h. mode; ref. 25.
Start
The appliance operates in the
d.h.w. mode and does not op-
erate in the c.h. mode.
When d.h.w. withdrawal
is terminated, does the
burner immediately
shut off?
NO
When d.h.w. is not being
withdrawn, is power fed to
NO
the 3--- way valve? ref. 27
YES
--- The motor in the 3--- way valve is faulty, or there is
an open circuit in the cable to the valve. ref. 30
rev. 17.09.93
--- Air is present in the d.h.w. heat ex-
changer.
--- The by--- pass valve is faulty.
--- The flow switch on the main circuit
is faulty.
YES
When d.h.w. is withdrawn,
YES
do the contacts open in the
flow switch on the main cir-
cuit? ref. 26
--- The d.h.w. temperature probe is short---
circuited.
--- The electronic regulation p.c.b. is faulty.
--- The by--- pass valve is faulty or
incorrectly calibrated.
--- The main circuit flow switch is
faulty.
YES
When d.h.w. withdrawal is
terminated, do the contacts
open in the main circuit flow
switch? ref. 26
--- The electronic regulation p.c.b. is faulty.
NO
YES
NO