Frequently Asked Questions

We have assembled a list of frequently asked questions about heaters and supporting tech. Whether it’s about part numbers or settings, you’ll find the most popular questions and answers below. If you don’t see your question, please contact our product support department.

The solid state switch controls the heat output within a much narrower range than the older switches. The better the heat output is controlled, the less expansion and contraction occurs within the combustion tube. Less expansion and contraction does not work harden the metal as quickly, which adds additional life to the combustion tube.

The integrity of the combustion tube for leakage and leaks from the fuel regulator on all “B” series Janitrol heaters.

The integrity of the combustion tube for leaks on the Southwind 940 and 8200 series heaters. Has been recently superseded by AD2017-06-03.

Superseded AD81-09-09 and covers the integrity of the combustion tube for leaks. Required compliance within 10 TIS, at next scheduled maintenance or 30 days after the effective date of the AD (May 5, 2017). This AD added a calendar time for overhaul along with PDT testing each 250 hours. The AD also prohibited repairs on combustion tubes.

This is a Pressure Decay Test required on all heaters as a maintenance function and some heaters under the requirements of an existing AD. On most heater models, this test requires pressurizing the combustion tube at 6 +/- .5 psig with a maximum leak down of 5 psi permitted over 45 seconds. The exception would be the Southwind heaters that require the combustion tube to maintain the 6 psi for the entire 45 seconds.

The preferred method is to install a Hobbs meter directly on the heater which measures the exact time of heater is operating. An alternate method is to use the aircraft Hobbs meter where one heater hour is recorded for each two flight hours.

  1. Fuel System – after any warm season or inactivity and prior to cold weather use, check the fuel system for contamination. Air System – Check inlet air from outside and outlet air to cabin for restrictions or damage.
  2. Air System – Check inlet air from outside and outlet air to cabin for restrictions or damage.
  3. Ignition System – Inspect and clean the spark plug.
  4. Exhaust System – Inspect the tube and shroud, if applicable, for security from the heater through the aircraft skin.
  5. Electrical System – Check the wiring harness for evidence of deterioration, overheating and security.
  6. Operation – Perform an operational check.

Verify you have the three basic requirements to support combustion:

  1. Combustion airflow – Is there airflow coming from the heater exhaust pipe?
  2. Ignition – Can you hear the spark plug sparking? It will sound like a “buzz” or a hive of bees inside the combustion tube.
  3. Fuel – Can you smell fuel in the exhaust?

Look for fuel dye stains at the regulator seams and threads.

No, the use of Teflon tape may require the heater to be overhauled.

The common rule of thumb is when the landing gear is extended, the heater should be shut down, unless, of course, you are operating in an extremely cold climate. Cold climate operation would recommend running the heater at its lowest temperature for approximately 2 minutes prior to heater shut down.

It depends mostly upon brand/type of heater and manufacture dates. If any doubt as to applicability to a specific unit call HET product support for assistance.

There are a few malfunctions that can produce this condition. The most common is low fuel pressure feed to the spay nozzle coming from the heater fuel pump. Depending upon the heater model pressure rates can vary so you should contact HET for further information specific to your heater systems fuel requirements.

Many of the spark plugs can be tested independently from the ignition unit. If your plug sparks on the separate testing unit it will indicate that the ignition unit itself could be the main culprit.

The majority of all of HET heater manuals are available at ATP. Should you not be able to find the information you are looking for, contact HET product support for assistance.

Please see the product line home page, select “Support” and then “Warranty”.

Please see the product line home page, select “Support” and then “Warranty”.

If parts and/or labor are approved under the commercial portion of the ASB or SB, complete the claim form at the end of the bulletin and return to the physical or email address provided in the ASB or SB.

Within 12 months from date of invoice, any unit returned for core shall be as removed from the aircraft, be complete and not disassembled. The core must be identified with an original data tag. Missing data tags or original ink-stamped identification will not be accepted. A percentage of the core value will be charged for all missing or damaged parts.

Any product returned for warranty consideration shall be as removed from the aircraft, be complete and not disassembled. All external parts including, but not limited to, brackets, fittings, bafflings, etc. shall be removed prior to shipment as they will not be returned.

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