Hayward 150 - User Manual

Questions and Answers

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ufryeJul 31, 2025
What to do if my Hayward 150 Gas Heater displays 'LO' with a Temp. Limit Switch Fault?
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  Brenda BrooksJul 31, 2025
  The 'LO' code on your Hayward Gas Heater, accompanied by a Temp. Limit Switch Fault, can often be resolved by checking the temperature limit switch wiring. Ensure the wire harness terminals are securely fastened to the spade terminals on the temperature limit switches. If the wiring is secure, but the issue persists, remove the wire leads from the limit switch and use jumper leads to operate the heater. Measure continuity across the limit switches. If closed, the 'LO' code is not caused by a temperature limit switch fault. If open, replace the temperature limit switch. Also, verify that the water flow rate to the heater is above the minimum required.
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Amanda CoffeyAug 4, 2025
What to do if my Hayward Gas Heater displays 'LO' with a Water Pressure Switch Fault?
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  bryanmillerAug 4, 2025
  The 'LO' code on your Hayward Gas Heater, when accompanied by a Water Pressure Switch Fault, is a normal display when the pump is off. Turn the pump on to see if the 'LO' code clears. If the code persists, verify that the water flow rate to the heater is above the minimum required. Also, inspect the water pressure switch wiring, ensuring the wire harness terminals are securely fastened to the spade terminals on the water pressure switch. If the heater is above or below water level, adjust the water pressure switch setting as presented in the manual. If the 'LO' code still does not clear, replace the water pressure switch.
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April MitchellAug 9, 2025
What to do if my Hayward 150 Gas Heater displays 'LO' with a Vent Pressure Switch Fault?
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  karla97Aug 9, 2025
  If your Hayward Gas Heater displays 'LO' with a Vent Pressure Switch Fault, start by inspecting the vent pressure switch wiring. Make sure the wire harness terminals are securely fastened to the spade terminals on the vent pressure switch. If the wiring is secure, remove the wire leads from the vent pressure switch and use jumper leads. Operate the heater and measure continuity across the vent pressure switch. If it's closed, the 'LO' code isn't due to a vent pressure switch fault. If it's open, ensure that the flue isn't blocked or restricted. Also, verify the heat exchanger and burners are not blocked. If the issue remains, replace the vent pressure switch.
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fmccarthyAug 17, 2025
What does 'AC' displayed on Hayward 150 mean?
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  Elizabeth WaltonAug 17, 2025
  If your Hayward Gas Heater displays the 'AC' code indicating an Air switch circuit closed error, disconnect the blower plug from the ignition control board. With the heater off, measure continuity across pins 1 and 2 of the receptacle on the ignition control board. If the circuit is closed, the ignition control board relay is defective, and you should replace the ignition control board. If the relay is OK, replace the blower vacuum switch.
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hillhollyOct 26, 2025
Why won't my Hayward Gas Heater power on and shows no code?
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  Jennifer OliverOct 26, 2025
  If your Hayward Gas Heater won't power up and shows no code, start by disconnecting the plug from the P5 connector on the Fuse Board and measure for 24VAC between the pins of the receptacle on the Fuse Board. Reconnect the plug. Then, disconnect the plug from P6 of the Fuse Board and measure for 120VAC between pin 3 and 5 of the receptacle on the Fuse Board. Reconnect the plug. If this is OK, proceed to the section titled ‘‘Low voltage circuit fault’’. Otherwise, proceed to step 2. Measure for field supply voltage across terminals of TB1 terminal block on Fuse Board. If OK, proceed to step 3. Inspect Fuse Board wiring. Ensure all plugs are securely fastened to Fuse Board. If OK, proceed to step 4. Remove FC1 and FC2 fuses from fuse holder. Measure continuity across fuse. If fuses are open,...
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Victoria WallaceNov 12, 2025
What does it mean when my Hayward 150 Gas Heater displays 'LO' with Exhaust Gas Temp. Limit Fault?
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  Veronica JonesNov 12, 2025
  If your Hayward Gas Heater displays 'LO' along with an Exhaust Gas Temp. Limit Fault, begin by inspecting the temperature limit switch wiring. Ensure the wire harness terminals are securely fastened to the spade terminals on the temperature limit switch located in the flue collector panel above the center of the header. If the wiring is secure, remove the wire leads from the limit switch and measure continuity across the limit switch contacts. If closed, the 'LO' code is not caused by an exhaust gas temperature limit switch fault. If open, this is generally due to low water flow, poor water chemistry, or other factors. Correct issues with water flow through the heater and water chemistry and then replace the heat exchanger and exhaust gas temperature limit. Continuing to run the heater aft...
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David MoraNov 21, 2025
What does it mean when my Hayward 150 displays 'No code displayed Low voltage circuit fault'?
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  Katrina JohnsonNov 21, 2025
  If your Hayward Gas Heater displays 'No code displayed Low voltage circuit fault', disconnect the plug from the P5 connector from the Fuse Board and measure for 24VAC across the pins. Reconnect the plug. If this is OK, proceed to step 2. Otherwise, proceed to step 5. Inspect the ignition control board wiring, ensuring all plugs are securely fastened. If everything is OK, proceed to step 3. Verify 24VAC across the R and C terminals on the ignition control board. If not OK, replace the harness. If it is OK, proceed to step 4. Remove the F1 fuse from the fuse holder and measure continuity across the fuse. If it's OK, replace the ignition control board. If the fuse is open, proceed to the section titled ‘‘Open FC3 or FC1 Fuses’’. If OK, reinstall fuse and proceed to step 6. Disconnect plug fro...