Making seasonal inspections of your furnace and air conditioning system makes sense, and I’d highly recommend having it done on a regular basis on any age furnace and AC units.

The question is – do you trust your HVAC guy?

Most people do, because they are always very happy to announce at the beginning of a home inspection that their heating and air conditioning system was JUST serviced by a professional, and it is in a perfect condition.

This statement always makes me suspicious of some hidden issues, and in most cases, I end up delivering a rather unpleasant message to the home owner …that he just dumped a $100.00 HVAC checkup fee into the drain.

This has happened many times already and I always feel sorry for the homeowner, but in a particular home inspection, I finally got proof that I can present to you. In this case, the HVAC guy taped his invoice to the front of a 20 year old furnace with an explanation of his work.

Direct vent furnace inspection invoice
“Check furnace and A/C and found no problems, I cleaned the evaporator coil + drain. Tested operation – Good.
Unit look good for its age and operates normal.”
$89.00

Armstrong, direct vent furnace components locationThe appliance was a direct vent forced air furnace with a cooling unit, everything in one box. It was installed in a townhouse utility room with its back compartment open to the building exterior. I’ve seen many of those units, usually in condominiums, and I know from my experience that heat exchangers in this particular type of a direct vent furnace / AC combo often fail within 15 years, and 20 is a significant stretch.

Heavily contaminated air return compartment under the AC coilThere are usually two service panels: one gives you access to the air conditioning coil and air filter, the second is for the burners. The filter and AC coil behind the first panel looked OK, but the condensate pan and condensate drain tubing was leaking, there was standing water on the floor underneath the coil / floor heavily contaminated, and black mold covered the air return compartment – old stuff, something that accumulated there over the years.

Severely corroded burner chambers in a direct vent type furnace - AC combo unitI already had a huge headache, because my sinuses suffer in a moldy environment, so I moved over to the furnace’s second compartment to finish the job. Unfortunately, it took a while to remove screws holding this access panel (one was severely corroded) and I’m 100% sure that nobody even attempted to open it for a long time (certainly not 3 days ago).

As I expected from this 20 year old direct vent furnace, areas around the burner chambers showed severe corrosion but no visible holes or cracks.

  • Direct vent type furnaces utilize air from the house exterior for combustion (gas burning process) purposes. Because exterior air usually contains more moisture than conditioned air from the house interior, it accelerates corrosion of the furnace internal components – heat exchanger.
  • The gas furnace heat exchanger – it is a metal separator between two areas inside the furnace. One area is where the fire is burning; the second area is where the air stream is pushed by the blower fan into the air ducts and registers (some very old furnaces operated without blowers). When that separating piece of metal cracks, Carbon Monoxide, which is a bi-product of an incomplete combustion, might leak into the air stream … and cause your death.

The good thing about most of those direct vent type furnaces is that you can easily access the heat exchanger for evaluation – as long as you can remove all of the corroded screws holding the furnace heat exchanger compartment access panel.

Direct vent furnace inspection - cracked heat exchanger #1Direct vent furnace inspection - cracked heat exchanger #2It was not easy, but I was finally able to lift the panel a few inches and take some pictures from the furnace heat exchanger interior. No surprises there, corrosion and several cracks along the edges of the metal tubes that serve as the heat exchanger.

Lets summarize our findings and compare them with the verdict from the HVAC professional:

  1. Furnace / AC compartment contaminated with potentially hazardous mold, distributed through the house every time the system is turned on – visible from the furnace air filter access panel / no comment from the HVAC service person
  2. Heavily leaking condensate drain pipe, water accumulating on the floor inside the air return compartment, water soaked framing of the compartment – HVAC professional claims cleaning the AC coil condensate drain pipe, not mentioning leaks and standing water
  3. Furnace heat exchanger severely corroded and cracked in many places – potential life threatening hazard / possibility of Carbon Monoxide poisoning – there’s not even one word in the HVAC service description mentioning severe corrosion and dangerous cracks of the furnace heat exchanger …

And the owner paid almost $90.00 for a statement that everything is OK

Before you hire a contractor:

  • do some research on the internet to find out the basic “How To” for whatever type of service you need
  • ask friends for recommendations
  • check credentials of the contractor
  • ask if there’s any warranty to cover performed work
  • follow the servicing person if possible (not invading his work space of-course)
  • ask him to explain what is he doing.

This poorly performed furnace / AC inspection is not just a single accident, it happens very often, and remember – it’s your money that ends up in somebody else’s pocket.

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