What does Raypak OUTLET SEN mean?

The XTherm or MVB controller has detected an abnormal reading or an open or shorted condition from the outlet water temperature sensor, so it cannot trust the leaving-water temperature.

What does Raypak LIMIT SEN mean?

The controller has detected an abnormal condition from the high limit temperature sensor and can no longer rely on it to protect the heater against overtemperature.

What does Raypak INLET SEN mean?

The controller has detected an abnormal reading from the inlet water temperature sensor. The inlet sensor lets the control measure return-water temperature and calculate the temperature rise across the heat exchanger, so a bad reading triggers the INLET SEN error.

HVAC

Raypak error codes, decoded.

Look up any Raypak fault code below. Each one is grounded in Raypak's own service documentation — the meaning, the symptoms, the causes, and the steps to clear it.

By Octavian Ghindea

Co-founder & CTO · Reviewed August 2026

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Raypak sits in our HVAC coverage. Every page here is transcribed from the manufacturer's manuals, not scraped from forums.

What error codes does Raypak display?

Tap a code for the full breakdown — meaning, symptoms, causes, and fix steps.

OUTLET SEN

Outlet water sensor fault on the XTherm/MVB controller display.

LIMIT SEN

High limit sensor fault on the XTherm/MVB controller display.

INLET SEN

Inlet water sensor fault on the XTherm/MVB controller display.

GAS PRESS

Gas pressure / PIM wiring related error on the XTherm/MVB controller display.

IGNITION

Ignition fault on the XTherm/MVB controller; clear with RESET.

LIMIT TRIP

Heater temperature tripped the high limit on the XTherm/MVB controller.

FLAME

False flame detected on the XTherm/MVB controller display.

ID CARD

Identity card fault on the XTherm/MVB controller; check ID card and wiring.

IGN CTRL

Internal control fault on the XTherm/MVB controller; reset power, replace control.

DELTA T

Temperature difference between inlet and outlet exceeded the setpoint.

LOW 24VAC

Low 24 VAC power; check power supply wiring and transformer.

BLOW SPEED

Blower speed out of range; check blower wiring and blower.

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