Furnace "Flash" and odd fan cycle

Old 10-14-04, 04:31 PM
Jim NJ
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Question Furnace "Flash" and odd fan cycle

Hi guys,
2 things on this Heil Durafuse heater (no other model number or year to be found).

1) About 2 - 3 seconds after the burners ignite there is a "flash" or "Woosh" above the place where the gas nozzles blow into the burner "tubes". There is about an 1.5 inch gap between the nozzles and the tube openings so I assume this flash is caused by some gas not flowing down the tubes and gathering at this location. This can't be normal right? Anything I can do to correct this?

2) The blower fan - after the thermostat is satisfied and the burners and fan shut off in about 45 seconds the blower fan starts again runs for less than 30 seconds than shuts off only to restart about 3 minutes later (again without the burners on) for about 30 seconds again. After those gyrations it does not start again until called for by the thermostat.

Any thoughts would be apreciate.


Found the model number HDGD150AH01

Last edited by Jim NJ; 10-14-04 at 04:52 PM. Reason: Found model number
Old 10-15-04, 01:02 PM
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Hello Jim. Welcome to the Heating Furnaces forum topic and the Do It Yourself Web Site.

Correct. Noise and or flash not normal. Usually caused by some tiny obstruction in the tube going to the burner. If any found clear and clean as needed.

Another possibility is the orifice is not lined up to the center of the burner tube correctly. Be sure burner is correctly seated on the orifice and no dust or lint is on the orifice(s) either.

Likely cause is air flow restrictions. May be caused by dirty air filter or too many registers closed off or not fully opened. Fan cycles back on and off to remove residual heat and buildup of heat in the firebox. Check filter, dampers and or registers.

If unit also has A/C, the A/C coils may be restricted with dust. Cleaning required.

Heating Agents & Appliance part stores stock replacement parts for almost every heater brand. The locations for the dealers, agents and retail part stores are listed in the phone book.

Check back on your question several more times. Heating professionals and other members posting replies in this forum topic may offer you additional advice, ideas and or repair methods.

Use the reply button to add additional information or questions. Using this method moves the topic back up to the top of the list of current questions automatically.

Be sure the electrical power to the appliance is turned off, the thermostat is turned down and the gas control valve is in the off postion before attempting any repairs or cleaning.

Regards & Good Luck. Sharp Advice.
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Old 10-15-04, 01:53 PM
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Location: Mountain Williams Missouri
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You dont say what furnace you have there are how old it is.
Take and make sure the venturi in the burners are clean and like no spider web's up in there also ckeck the pilot lighter stripthatit is clean.
On the blower if old unit just has the summer blues. When the blower control is set just about right. And its just cool out the furnace comes on heats up . The blower comes on the tstat shuts off the burner. The blower runs a time and shuts off. but the air was not real cold comeing to the blower .So it didnt cool the furnace all the way then the blower control will turn the blower back on for just a little bit. Yes the duct layout and the filter have a lot to do with this. If everything is ok on the furnace this will stop as soon as it get colder outside.

Old 10-15-04, 06:12 PM
Jim NJ
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Sharp, Ed,

Thanks for the response - I will check those items suggested.

Old 10-17-04, 01:26 PM
Jim NJ
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Found that the burner tubes move a little - pulled them toward the gas nozles and now no more flash.


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