Hayward 150 - Water Pressure Switch Fault Diagnosis; Vent Pressure Switch Fault Diagnosis

USE ONLY GENUINE REPLACEMENT PARTS 47
51300004201B
Table17: Troubleshooting Lookup Chart
Code/ Fault
Diagnostic Step
Suggested Troubleshooting Action
LO
displayed
Water
Pressure
Switch Fault
1. Verify that the
pump is running.
This is a normal display when the pump is off. Turn pump on. LO code
should clear. If LO does not clear, proceed to step 2.
2. Verify that water
flow is adequate
Verify that water flow rate to heater is above minimum required (see
SPECIFICATION in Getting Started Section). If OK, proceed to step 3
3. Check for faulty
wiring or
connection.
Inspect water pressure switch wiring. Ensure wire harness terminals are
securely fastened to spade terminals on water pressure switch. If OK,
procced to step 4.
6. Check for correct
water pressure
switch setting.
Adjust water pressure switch setting as presented in Manual (only if heater
is above or below water level). If LO does not clear, proceed to step 7.
7. Water pressure
switch is defective
Replace water pressure switch.
LO
displayed
Vent
Pressure
Switch Fault
cont…
1. Check for faulty
wiring or
connection.
Inspect vent pressure switch wiring. Ensure wire harness terminals are
securely fastened to spade terminals on vent pressure switch. If OK,
proceed to step 2.
2. Verify state of
vent pressure
contacts.
Remove wire leads from vent pressure switch and jumper leads. Operate
heater. Measure continuity across vent pressure switch. If closed, LO code
is not caused by vent pressure switch fault. If open, proceed to step 3.
Remove jumper from wire leads and reconnect wire leads to vent pressure
switch.
3. Check for
restricted or blocked
flue.
Ensure that flue is not blocked or restricted. See indoor vent sizing
requirements in installation manual. Verify heat exchanger is not blocked.
Verify burners are not blocked. If OK, proceed to step 4.
4. Vent pressure
switch is defective.
Replace vent pressure switch.
LO
displayed
Temp. Limit
Switch Fault
cont…
1. Check for faulty
wiring or
connection.
Inspect temperature limit switch wiring. Ensure wire harness terminals are
securely fastened to spade terminals on temperature limit switches. If OK,
proceed to step 2.
2. Verify state of
temperature limits’
contacts
Remove wire leads from limit switch and jumper leads. Operate heater.
Measure continuity across limit switches. If closed, LO code is not caused
by temperature limit switch fault. If open, proceed to step 3. Remove
jumper from leads and reconnect leads to temperature limits.
3. Verify that water
flow is adequate
Verify that water flow rate to heater is above the minimum required (see
SPECIFICATION in Getting Started Section). If OK, proceed to step 4.
4. Temperature limit
switch is defective.
Replace temperature limit switch.