Heating, Air Conditioning, Fridge, HVAC/Furnace Blows cold air

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Question
My furnace blows hot air through the flu, but cool air into the house.  I have a great flame with all the burners and am concerned that it is a faulty/broken heat exchanger.  Thoughts?

Answer
Cameron,

Check your return duct first to make sure it's sealed as to not bringing in any cold surrounding air into your return, it may be open somewhere and drawing cold surrounding air into your duct ,which would mix with your return air giving you a colder than normal air temperature coming out of your supply registers. Your gas valve at the furnace may be not set correctly, your opinion of a great flame at the burners may not be my opinion of a great flame, your gas pressures may be low at the furnace gas valve. How was this system working last year? If you have concerns about the HX being faulty, call a Reputable Contractor to check it or your local gas company.You can also determine if your return duct is pulling surronding cold air into the duct by running only the blower fan, by placing the fan switch at the t-stat to ON from the auto postion, leave the heat off and having a cool heat exchanger place an accurate thermometer on a supply register(s) then move to your return register(s) ,they should be the same temp. if your supply air temp.is colder then your ductwork has issues.  

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40+ years diversified experience.An HVAC/Refrigeration Self Employed Contractor since 1986. NATE Certifield. Answer questions pertaining to Residential and Commercial Air Conditioning , Warm Air Heating, Heat Pump systems.Mechanical and Electrical troubleshooting of these systems.Be as detailed as possible when describing problem.Packaged unit or split systems.No appliance questions.

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Installation and Troubleshooting, Mechanical and Electrical, in following areas, Refrigeration ( Walk In and Reach In Coolers and Freezers ) Commercial Roof Top and Packaged Heating/Cooling ( Natural Gas,Propane, Electric, and Heat Pumps ) Computer Room Air Conditoning Systems,Commercial Residential Packaged and Split Systems Air Conditoning and Heat Pumps.Warm Air Oil , Natural and Propane Gas Heating systems.

Education/Credentials
Graduated from Private Technical School in 1975. An HVAC/Refrigeration Contractor . Have Unlimited Heating/Piping and Cooling Contractor License.Limited Sheetmetal Contractors License.NATE Certifield. York Certifield Master Heat Pump Technician 1986. Served 33 years combination Active Duty Air Force , Air Force Reserves and Air National Guard in the HVAC/Refrigeration Shop/Mechanical Shop. Troubleshooting/Installing HVAC/Refrigeration Equiptment Worldwide. Retiring in 2003 as a Senior NCO ,and a Mechanical Superintendent.

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