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AC Line set too close to exhaust ductwork

I assume you are talking about the flue pipe or smoke pipe, not ductwork. The bigger issue is that any combustible material must be 18" from single wall flue pipe. The melted insulation should be a clue that this is a fire hazard and, as such, the line set should be relocated.


    DUNBAR Member Posts: 1
    AC Line set too close to exhaust ductwork

    Is there any code guideline that AC line sets have to remain clear of the ductwork either of the furnace or water heater?

    This mainly pertains to the water heater as the AC unit would never operate during the same time that the furnace would be running.

    The job I was on had the line set dropping between the the furnace ductwork and the flue for the gas water heater withing a 1/2" of each other.....and no way you could put a finger between the two on each side.

    I'm no heat and air guy but I keep running into similar situation and seeing the armaflex burned off the line sets.....knowing that cannot be efficient since that temperature of the refrigerant needs to be free of any situation that can change it dramatically before it goes into the A-coil.

    The only time this situation would present itself is when summer weather along with periodic use of the water heater.

    I advised the homeowners to have the HVAC guys come out and reroute that line set somewhere else other than between the two pipes.

  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    The cooler the better

    No matter how well the suction line is insulated, the refrigerant in the suction will pick up heat from its surroundings, as long at the ambient temperature is higher than the temperature of the suction gas.

    It stands to reason that, from the above statement, refrigerant lines should be directed away from any external heat source, such as a water heater or the flue pipes that carry the combustion gases away.

    Although this will have an effect on system efficency, I doubt that the additional efficency that will be gained by rerouting the pipes will offset the cost of having a technician come in to actally move the pipes... Hmmmmm

    It pays to do it right the first time!
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