Hayward Universal H-Series heaters show two-letter codes like LO or IF. Many point to low water flow, gas supply, or a sensor. Lucent Pools repairs Hayward heaters across DFW. Call 817-339-6770.
Based in Dallas–Fort Worth, serving Fort Worth, Frisco, Lewisville, and most of the DFW Metroplex.
We repair pool heaters in Fort Worth, Frisco, Lewisville, and most of the DFW Metroplex.
We repair in-ground pools and in-ground spas. We do not repair portable hot tubs.
We service and repair all pool equipment brands, including Jandy, Pentair, and Hayward. We are an Authorized Jandy ProEdge Warranty Station and can also help with Pentair and Hayward warranty claims.
If you smell gas, don't light any appliance and don't touch electrical switches or use a phone in the building. Call your gas supplier from a neighbor's phone, or the fire department if you can't reach them. Hayward's manual tells owners to contact a qualified service company when an error code shows. Never open the gas valve, burner or any gas part yourself. Don't use the heater if any part has been under water.
What does LO mean on a Hayward heater?
LO means a switch in the heater's safety "limit string" is open, so the heater shuts down. Most often it's the water pressure switch not sensing enough flow; it can also be the vent pressure switch or a temperature limit switch. LO is normal when the pump is off, and the heater restarts on its own about 2 minutes after the problem clears.
You can check that the pump is running and primed, the pump and skimmer baskets are clean, the filter is clean or backwashed, the valves are open, and a variable-speed pump is not set too low. If it keeps saying LO with the pump running, a technician should check flow through the heater, the pressure switch, the limit switches, and the vent pressure switch. The internal bypass can also cause low or high flow. That is pro work.
The same code shows as lowercase lo. A Service light on with LO is this code. Hayward Universal H-Series owner's manual 1301640701 Rev G, Figure 4, and service manual 1301623301 Rev T, Figure 27, call LO a normal display when the pump is off. See pool pump repair and pool filter repair.
What does IF mean on a Hayward heater?
IF is ignition failure: the heater tried to light, couldn't, and locked out. Hayward's control makes three tries before it locks out, then tries again on its own after 60 minutes. Common causes are a gas supply problem, a worn igniter or flame sensor, or a gas valve or control fault.
A display that looks like 1F is IF. After a loss of flame, the heater makes ten attempts. Hayward Universal H-Series service manual 1301623301 Rev T states the three ignition trials, then a 60-minute lockout.
Make sure other gas appliances work and the propane tank isn't empty. Don't turn gas valves or open the heater; call us or your gas company.
We repair and replace gas and propane pool heaters. Gas line work, including new runs and changes to existing lines, is done by our licensed gas contractor, with permits where required.
Everything inside the heater: call.
What does HS mean, and why does it keep coming back?
HS means the water coming into the heater is too hot (over 104°F) or its temperature is climbing too fast while the heater fires, which Hayward says points to low water flow. It clears on its own once the temperature settles. If it happens three times in an hour, the heater locks out until its power is turned off and back on. Call a technician.
Check flow first, the same checks as LO. Reversed inlet and outlet plumbing causes frequent HS. That is a pro check. A display that looks like H5 is HS. HS is a temperature problem; SF is a sensor problem.
What does SF mean on a Hayward heater?
SF is a temperature sensor (thermistor) error. The heater has two sensors, and SF shows when they disagree by 5°F or more, or both read outside a normal range. It needs a technician with a meter; the heater restarts about 2 minutes after the fault is fixed.
On a Hayward heater, SF is the water temperature sensor, not a flue or stack sensor. It is usually a failed thermistor, a loose plug, or the control board. Hayward Universal H-Series owner's manual 1301640701 Rev G, Figure 4, lists this code.
What do AO, AC and IO mean?
AO and AC are blower vacuum switch codes: the switch that proves the combustion blower is moving air is open when it should be closed (AO), or closed when it should be open (AC). IO means the igniter circuit is open. All three stop the heater from lighting.
Keep the vent and the area around the heater clear of leaves, nests and debris. Blower, tubing, switch, and igniter checks are pro work. A display that looks like 10 is IO.
What do PF, CE, bD, HF, EE and Sb mean?
These are electrical and control faults. PF is a supply wiring problem (reversed polarity, low voltage or a poor ground); CE means the display and ignition boards aren't talking; bD, EE and HF point to the control board or gas valve circuit. Sb means a keypad button is stuck, and the heater keeps running.
Hayward prints the board code as bD (bd). HF means flame is sensed with the gas valve off. That is a lockout: shut the heater off and call; don't reset it.
We repair anything electrical on your pool, from pumps, heaters, and automation to timers, salt systems, and pool lights, and connect or disconnect it on your existing circuits. Call a technician.
What does "bo" mean on a Hayward heater?
"bo" isn't an error. It means the heater is in bypass mode, which hands control to an outside system such as pool automation. If you don't have automation running the heater, or the heater won't respond, call 817-339-6770.
Hayward's consumer troubleshooting guide CTSG-UHS16b calls this bypass operation. See pool automation repair.
How do I reset a Hayward heater, and is it safe to keep resetting it?
Hayward's manual clears codes with the MODE button, not a reset button. Pressing MODE to go to STANDBY and back to POOL or SPA clears a code, and many codes clear on their own once the problem is fixed. If the same code returns, stop and call.
One MODE reset is OK, and up to a 5-second delay is normal. Never keep resetting IF or HS lockouts, and never reset HF. If the HS lockout is on, call a technician. Hayward Universal H-Series owner's manual 1301640701 Rev G describes the MODE clear, and service manual 1301623301 Rev T notes the automatic reset time.
Which Hayward heaters does this cover?
The Universal H-Series gas heaters (H150FD through H500FD, natural gas and propane, including ASME versions) share these codes. If your heater shows a code not listed here, note the exact code and the model on the rating plate, and call.
These codes are the table in the Hayward Universal H-Series owner's manual 1301640701 Rev G and service manual 1301623301 Rev T, and in consumer troubleshooting guide CTSG-UHS16b. This guide does not cover HeatPro heat pump codes, the Universal HC Series, older pre-Universal H-Series heaters, or Australian tables.
We service and repair all pool equipment brands, including Jandy, Pentair, and Hayward. We are an Authorized Jandy ProEdge Warranty Station and can also help with Pentair and Hayward warranty claims.
When to call a pro
Check flow, power, gas supply and the area around the heater yourself. Anything inside the cabinet, any gas part, and any code that returns after those checks is a job for a technician.
| You can check | Call a technician |
|---|---|
| Pump running, filter and baskets clean, valves open (LO) | LO that stays with the pump running |
| Heater in POOL or SPA, set point above the water temperature | HS that comes back, or any HS lockout |
| Other gas appliances work, propane tank not empty, vent and area around the heater clear of leaves or nests | IF, AO or AC that comes back, or anything that needs a panel removed |
| Press MODE to STANDBY and back to POOL or SPA once | The same code after one reset |
| Any electrical or board code (PF, CE, bD, EE, HF), and SF or IO |
Don't open the heater or touch gas parts.
Repair or replace a Hayward heater?
Most codes point to a part that can be repaired or replaced: an igniter, sensor, switch, blower or board. Replacement makes sense when the heat exchanger has failed or repairs keep stacking up.
Repair first, whatever the brand. When replacing, we usually recommend Jandy. The customer chooses, and if they'd rather stay with Hayward, we supply and install it. The reason is the 3-year warranty on new Jandy equipment we install.
Low pH, high sanitizer, or high pH, alkalinity, or calcium can damage the heat exchanger. See residential pool maintenance.
See pool heater repair in Fort Worth and DFW. See pool repair in Fort Worth and DFW. Related guides: Jandy heater error codes and Pentair heater error codes.
Is my Hayward heater still under warranty?
Check your install paperwork and the model and serial number on the heater's rating plate. We are an Authorized Jandy ProEdge Warranty Station and can also help with Pentair and Hayward warranty claims.
- 25+ Years in the Pool Business
- Lucent Pools is insured.
- Lucent Pools is CPO certified by the Pool & Hot Tub Alliance (PHTA).
More help: pool repair in Fort Worth and Dallas–Fort Worth, pool repair in Argyle, pool repair in Hurst.
Need a Repair?
What a repair costs depends on the part; we price it after diagnosis. Call 817-339-6770. Monday through Friday, 8:00 AM to 6:00 PM. Saturday closed. Sunday closed.
