Tuning up your Proheat

It's that time of year again to use your coach's  auxiliary heater for easier start-up. The Proheat® auxiliary heater unit installed on your MCI motor coach is a 24-volt, diesel-fired auxiliary heater. Under normal conditions, the unit adds approximately 45,000 BTUs of heat to the coach heating system.

On your coach, the Proheat serves two primary functions:

  1. Engine block heat. The unit preheats and helps maintain engine coolant temperature in cold weather. This function provides quicker and easier cold-weather starting, as well as reducing engine wear associated with cold operation.
  2. Supplemental heat. The Proheat unit provides additional heating capacity for the coach passenger compartment.

Keeping it humming

Proheat recommends regular operation of the unit throughout the year to improve reliability. Weekly use is recommended.

The Proheat® X45 unit is electronically controlled and monitors itself during operation. Normal operation and malfunctions are indicated on the controller face with a series of LEDs that illuminate to aid the technician in diagnosis. Detailed information for reading and interpreting the ECU LED indicators can be found in your MCI Maintenance Manual, section 16, or at

Routine maintenance is necessary to keep the Proheat unit in proper operating condition. Before performing any maintenance to your Proheat unit, check for any current service announcements.  You should also check the Proheat website for a copy of the service manual. Also see MCI Service Bulletin 2913.

In addition to regular daily inspection of hoses and connections, an operator should run the heater through a complete cycle a minimum of once a week to keep new fuel in the heater's critical components. A-1 diesel or Ulta Low Sulfur Bio Diesel Spec is B 5 Max for the heater to perform. If Bio Diesel is used, the fuel lines must be inspected twice a year per Proheat recommendations.

Annual tasks

The best time perform annual maintenance is prior to the onset of your area's heating season. Here are the manufacturer's recommendations:

  1. Clean heater enclosure:

    • Remove the heater enclosure and blow out the compartment with compressed air. Clean any accumulated debris or dust from the components. Make sure the opening around the exhaust pipe is clear. Visually inspect all components for wear or damage.
    • Clean the flame sensor.
    • Clean the sight glass using a clean cloth and standard window cleaner.
  2. Maintain your heat exchanger. To maintain optimum heat output, clean any combustion deposits that may have accumulated on the heat exchanger fins.

  3. Check the exhaust system carefully. Make sure the exhaust pipe is vented safely. Check for dents, restrictions or severely corroded areas. Replace the exhaust pipe and clamps if needed. Ensure that the exhaust pipe clamp is tight.

  4. Electrical system check: Check the internal and the external wire harness for damage. Replace if required.

  5. Clean air intake: Check the combustion air inlet screen for restrictions. Clean as required.

  6. Fuel system: Check the fuel system for damaged fuel lines or leakage. Make sure the clamps on the fuel lines are secure.

  7. Vehicle batteries: Check the condition of the batteries and power connections. The heater will not function properly with weak batteries or corroded connections. If you are unsure of their condition, load-test each battery separately and replace as required. Clean terminals to remove all corrosion.

  8. Operation test: Run the system for at least 15 minutes or until the heater cycles "OFF" and then "ON" again.

If you follow these simple steps, your coach should have a trouble-free winter, as far as your Proheat unit is concerned. For more maintenance information and a schedule, consult your Proheat manual or Section 16 of your MCI Maintenance Manual.

MCI also offers Proheat retrofit kits to convert from Espar or Wabasto to ProHeat on MCI E4500 and J4500 coaches. For more information or to order, contact your MCI product support specialist; MCI's customer service department at 800-323-1290; or MCI's technical call center  at 800-241-2947.

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Proheat is a registered trademark of Teleflex Incorporated.

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