Hayward Universal H-Series Low NOx Service/Installation: H150FDN H200FDN H25 - Page 56

56 Figure 53: Troubleshooting Code SF Fault Temperature sensor input failure Water Temperature Sensing Error HS Flame Present HF with Gas Valve not Energized Bypass Operation bO Water pressure switch fault LO Vent pressure switch fault (applies only if indoor installation) Diagnosis Step Remedy 1. Check for faulty wiring or Inspect sensor wiring. Ensure sensor is pluggd into back of control connection. module. If OK, proceed to step 2. 2. Sensor is defective Replace temperature sensor. 1. Check remote thermostat setting Verify set point setting of remote thermostat is at or below 104°F. If set point of remote thermostat is OK, or if heater is not configured for remote thermostat, proceed to step 2. 2. Verify that the water flow is adequate Verify that water flow to heater is above minimum required (20 GPM for H150FD and H200FD, 25 GPM for H250FD and H300FD, 30 GPM for H350FD and H400FD). Note that intermittent periods of low water flow will cause this error. If OK, proceed to step 3. 3. Check inlet water temperature sensor Compare the heater's temperature reading to the pool water temperature with an accurate thermometer. If significantly different, replace inlet water temperature sensor. 1. Gas Valve is defective Replace Gas Valve 1. Check to see if Control Module is in Bypass Operation This is normal display when heater is being controlled by a remote thermostat. No service is required. If heater is not being controlled by remote thermostat, change setting by using the MODE key to put the heater into STANDBY. Press and hold the DOWN key and then press and hold the MODE key. Hold down both keys for 3 seconds until the indication ''bO'' is removed from the display. 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 (20 GPM for H150FD and H200FD, 25 GPM for H250FD and H300FD, 30 GPM for H350FD and H400FD). If OK, proceed to step 3 3. Check for faulty wiring or Inspect water pressure switch wiring. Ensure wire harness terminals are connection. securely fastened to spade terminals on water pressure switch. If OK, procced to step 4. 4.Verify state of water pressure switch contacts. Remove wire leads from water pressure switch and jumper leads. Operate heater. Measure continunity across water pressure switch. If open, proceed to step 5. If closed, LO code is not caused by water pressure switch fault. Remove jumper from wire leads and reconnect wire leads to water pressure switch. 5. Ensure that low pump pressure does not exist. Clean filter or clear blockages. Check position of valves in plumbing system. If OK proceed to step 6. 6. Check for correct water pressure switch setting. Adjust water pressure switch setting as shown on page 33 of Installation Manual (only if heater is above or below water level). If LO does not clear, proceed to step 7. 7. Water pressure switch is Replace water pressure switch. defective 1. Check for faulty wiring or Inspect vent pressure switch wiring. Ensure wire harness terminals are connection. 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. If OK, proceed to step 4. 4. Vent pressure switch is defective. Replace vent pressure switch.