Modine has made us aware of a potentially serious safety issue. When separated combustion gas-fired heaters are used with a failed vent system the vent system seems to be allowing products of combustion to be recirculated back into the fresh air pipe. This can potentially cause a severe delayed ignition and could damage the unit, the unit casing, and possibly separate the bottom access panel from the unit (see Figure 1).

Modine heater with a missing bottom access panel.

All Modine separated combustion heating units, and their vent systems, must be inspected. Modine is recommending shutting down all heating units until the vent systems are inspected and verified to be working correctly.

Only visually inspecting the vent is not sufficient. Figure 3 shows a visual inspection of concentric vents. Figure 4 shows the vent system from Figure 3 upon further inspection. Vent caps must be removed to inspect the inner pipe and ensure it has no breaches.

Vents with and without the vent caps.

Two-pipe systems should also be reviewed to ensure the recirculation of products of combustion is not possible.

Separated combustion unit models include, but are not limited to:

  • PSH/BSH
  • HDS/HDC
  • PTS/BTS
  • PTC/BTC
  • DFS
  • DCS
  • IFS
  • IBS
  • ICS

Model PSH/BSH units were built between 1995 and 2007. All other models are currently in production.

Modine believes the following items may contribute to the potential safety issue:

  • Recirculation of products of combustion
  • A "universal" ignition control was installed to replace the original Modine ignition control.
    • All original Modine parts must be replaced with Modine approved service parts.
  • Preventative maintenance was neglected on units.

Inspections must be performed on all vent systems to make sure they are in proper working order. Also, preventative maintenance is required on all gas fired appliances. Modine suggests the inspection of vents on all gas appliances at least once a year.

Please contact Modine Technical Service at This email address is being protected from spambots. You need JavaScript enabled to view it. or 1.800.828.4328 if you have questions about this issue.

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