Rinnai Gas Heater Error Codes: EX38CT 11, 14 and 99

Record 11 before trying to clear it

Rinnai’s EX38CT code table calls 11 no ignition. It asks for a check that gas is on and the vent termination is not blocked, refers to the restart function, and requires a service call if the fault repeats.

Confirm the known supply status without dismantling anything. If the gas was deliberately shut off or you cannot identify the valve safely, tell service. Do not open an unknown valve, purge a gas line or force a control with tools. Rinnai’s operating instructions say a gas control that will not move by hand needs a qualified technician.

The EX38CT restart section describes an automatic ignition attempt after one hour when ignition fails. Code 11 remains visible during that interval and disappears after successful ignition. Rinnai also says this code is not stored in fault history, so a photo can help the service visit.

That automatic behavior is not an instruction to keep pressing buttons. Rinnai’s general code instruction says to arrange service if a code remains or returns on the next operation. Follow that boundary when no ignition keeps recurring.

Let the heater cool before filter care

Rinnai defines 14 as overheat. Its filter section explains that blocked filters can trigger a flashing filter lamp and beeping, followed by shutdown and code 14. The code table says to clean the filter and call service if the problem repeats.

Use the ON/OFF control and allow the cooling fan to finish. With the heater off and cool, Rinnai says to remove the accessible filters and clean them with a soft dry cloth or vacuum. For greasy filters, it specifies warm soapy water, rinsing and complete drying.

Refit the filters before operation. Rinnai prohibits using the heater without them. This filter procedure does not require removing the furnace’s front panel or cleaning its burner; leave that service work to a qualified technician.

If 14 returns, report the cleaned filter and repeated code. Rinnai says replacement of a fusible link belongs to a qualified service agency, which must also determine the cause of overheating. Do not bridge that safety device.

Keep a hot room separate from a vent fault

Rinnai calls 16 room overheat and specifies lowering room temperature below 104°F, or 40°C. It is a separate entry from code 14. Report which code appeared instead of describing both as the same overheat message.

For 99, Rinnai says to check around the flue terminal for blockage. Its maintenance instructions specifically require keeping the terminal clear of snow and ice because obstructed intake or exhaust affects operation.

Inspect only from a safe, accessible position. Remove a loose outside obstruction only when you can do so safely without touching hot parts or dismantling the flue. Do not climb to reach it, push anything into the terminal or disconnect the vent. If access is unsafe, have service inspect it.

Rinnai’s code-table footnote says the flue must remain clear to expel exhaust gases. If the appliance still fails to operate, contact a qualified service agency. A cleared outside opening does not establish that the entire vent system is sound.

Use the control button, not the plug, for the stated restart

Rinnai defines 73 as communication error and tells the reader to turn the furnace off, then on again. Use its ON/OFF control and preserve the fan’s cooling run. The manual’s general rule sends a code that remains or returns on the next operation to service.

The EX38CT table assigns service calls to codes 30 to 35, 49, 53, 61, 62, 70, 71, 72 and 81. Those rows concern temperature sensors, the sparker, fans, switches, solenoids or flame rod. They are not owner instructions to replace the named component.

Keep the exact message with the service request. Rinnai also calls for an annual inspection by a qualified service technician. Accessible filter care does not replace that inspection.