KISSIMMEE, Fla. - One helpful technical session both for consumer safety and for our energy-conscious times at this year's Air Conditioning Contractors of America Convention (ACCA) was delivered by Eric Kjelshus, who spoke on "Adjusting for Peak Efficiency - Looking for Holes." He has his own energy company in Greenwood, Mo., and has devoted much of his career to helping solve especially difficult heating-cooling problems, especially in older, more leak-prone homes.
An unsafe appliance could create a fire hazard or release deadly carbon monoxide, Kjelshus pointed out. As an hvac contractor, you have an obligation to alert your customers to unsafe equipment including, but not limited to, cracked and/or broke heat exchangers.
Have a copy of the local building code with you when making a call, he advises. It helps your customers understand why they may need to replace their heating system. "Just remember you should be completely familiar with your building codes, rules and regulations before starting a job."
"I like to heat up the heat exchanger before a visual inspection is made," Kjelhshus said. "A visual inspection is quick and reliable, and should be one on every air conditioning or heating job."
Most multiple chamber clamshell designs fail where airflow is lowest, he said: in back where the chamber narrows, although this is not the only heat build-up spot. "Cracks are very easy to find if the back is off but this is not acceptable protocol. You can find blower interference, if the pilot light moves or if the flames roll out the front of the furnace or under the burner. This is an immediate call problem inside the fire chamber."
Run the furnace through a full cycle to check the operation. Does the thermostat turn the gas valve on and off? Do the burners light properly? Do the safeties work? Is there a banging noise or whistling? Inspect the burner shield, flue and burner for corrosion, discoloration or mineral deposits. Remove the burner shield and two wires to the gas valve slide out burner. Removal of burners on newer furnaces takes more time but is the only way to see up into the heat chamber, according to Kjelshus.
"Most cracks are very visible on the outside of the heat chamber. If you find or suspect a crack, use water, soapy water or non-corrosive oil that will bleed through. This will help prove to the owner where the leaks are located."