By: Evan F. Grugett, CCA, ASHI® #169

NY State CEO Reg. #1191-7640B

"About Carbon Monoxide Detectors"

The heating season is right around the corner, about six weeks hence. It’s now time for the annual service call on the heating system. Your summer client, the buyer, may take the house over after October 15^th, and the system may not have been serviced and safety checked by a qualified technician. The seller considers themselves "out the door" and is often not performing such normal seasonal equipment maintenance.

Your own check of the heating system during a summer inspection may have been limited by the ambient temperatures, and certain equipment types (heat pumps for instance). It certainly wasn’t a "full load test" of the heating system on a summer’s day. The system ran on "normal household operating controls" at the time of the inspection. It also ran at the pre-closing inspection when the client turned on the thermostat. The furnace is not that old. It’s OK, right? Maybe it’s not!

Your report informs the client that the system should be serviced, tuned, and safety checked before each heating season. Your client closes on the house in November and follows your advice. They bring in the heating service for an annual tune up and safety inspection and find problems. The problem may be inside the unit (a cracked furnace heat exchanger for instance, or an integral coil that’s leaking inside the boiler), something that you couldn’t see on your inspection and couldn’t therefore report on.

Does that make the client feel any better with a furnace replacement staring them in the face for $4,000.00 or better? I don’t think so. Hopefully no one got sick or worse from fumes from defective equipment or venting. Would a carbon monoxide detector have helped in disclosing a cracked furnace heat exchanger, either during the inspection or at the pre-closing inspection?

Whether the Home Inspector should test for combustible gasses &/or CO with a detector is up to each practitioner to decide. I would strongly recommend that you do so, and not rely on the recent law change requiring the seller to furnish a working CO detector at the lowest bedroom level of the home (remember that was in the Fire Code, "all buildings all the time", not the Residential Code or the Building Code which are not retroactive to existing premises) for any protection. Remember, you can’t smell the gas after the flame.

Many of the CO detectors that I come across during inspections are installed at the ceiling, or high on the wall, the way smoke and heat detectors are. Some ceiling mounted, hard wired units, are actually combination CO, smoke and fire detectors (with UL labels on them!), and go for more than $300.00 per unit installed (as a new home builder recently bragged to me, he used the latest technology).

The problem is, that CO is about equal to or slightly heavier than air, and doesn’t rise the way heat and smoke do. It leaks out of the defective appliance or flue and settles to the floor. It fills up in the room the way water does in a pan, from the bottom up. Remember that most people die in house fires in bed from asphyxiation of the products of combustion. Heights of a bed off the floor vary from about 30" to 38" or more. That detector better be lower than that!

Incomplete combustion helps creates carbon monoxide, so excessive carbon monoxide is actually often the symptom of another problem. Equipment out of tune (is the flame yellow? Is there scaling at the burner area?), and lack of combustion and make up air in the fuel burning equipment space, are two common sources of carbon monoxide problems. Both can be spotted during a home inspection.

Be safe, check for carbon monoxide with a reliable hand held detector during the inspection. If the furnace or boiler is in poor condition, rusted, even if it’s within its industry accepted useful life, report that the unit could "fail at any time" although working at the inspection. Advise the client to have a heating technician open up the furnace to visually check the heat exchanger, before the contract is signed, if possible. Instruct the client in the proper location of carbon monoxide detectors both verbally and in the written report.