Carbon Monoxide Warning Signs Every Carlisle Household Should Know

The symptoms, and the pattern that identifies them

Carbon monoxide poisoning symptoms look like a lot of ordinary illnesses: headache, dizziness, nausea, weakness, confusion, and fatigue. In winter, people routinely dismiss them as flu.

• The distinguishing pattern: symptoms improve when you leave the house and return when you come back
• Multiple people in the household feeling unwell at the same time
• Pets showing symptoms too — they are often affected first because of their size
• Symptoms that appear or worsen when the heating system runs

Every source in a typical Carlisle house

• Gas, oil, or propane furnace or boiler with a cracked heat exchanger or poor venting
• Gas water heater — including the orphaned-flue problem described below
• Gas range and oven, especially when used for heat, which is never safe
• Fireplace or wood stove with a blocked, deteriorated, or improperly drafting flue
• A vehicle running in an attached garage, even briefly with the door open
• A generator running in a garage, basement, or under a deck during a power outage
• Any unvented combustion appliance — including outdoor propane heaters brought inside

The orphaned water heater: an upgrade that creates a hazard

This is the risk almost nobody warns homeowners about, and it is common in Carlisle’s older housing.

In many of these houses, the furnace and the gas water heater share a masonry chimney. When the furnace is replaced with a 95% condensing model, it moves to PVC sidewall venting. The water heater is now alone in a flue sized for two appliances.

A small water heater cannot generate enough heat to establish draft in an oversized flue. Exhaust cools, condenses, and can spill back into the basement rather than going up — which puts carbon monoxide into your house as a direct result of an energy-efficiency upgrade.

If someone replaced your furnace with a high-efficiency unit and never mentioned the water heater or a chimney liner, get it tested. This is precisely what a combustion and draft inspection is for.

Alarm placement, and the mistake nearly everyone makes

• One alarm on every level, and one outside each sleeping area, at minimum
• Alarms expire — most CO sensors are rated for 7 to 10 years from the manufacture date. Check the date printed on the back of the unit, not the box.
• Test monthly, and replace batteries on schedule, or buy sealed 10-year units
• Do not mount within about 15 feet of a fuel-burning appliance, or nuisance alarms will tempt you to disable it
• Add one near the door from an attached garage
• The mistake: assuming a smoke alarm detects CO. Most do not. Check whether yours is a combination unit — a great many people find out it is not.

Physical warning signs on the equipment itself

• Soot or a sooty film on or near the furnace, water heater, or vent connector
• Rust flakes on the vent pipe or the top of the water heater
• A yellow, lazy, or flickering burner flame where it should be crisp and blue
• Excessive window condensation near fuel-burning appliances
• A vent connector that has come loose, sagged, or corroded through
• Air blowing back down the flue that you can feel with your hand

What a proper safety inspection includes

Not every "safety check" is one. A genuine inspection is instrumented and covers every fuel-burning appliance, not just the furnace.

• Ambient CO measurement through the living space with a calibrated instrument
• Combustion analysis at each appliance — CO in the flue, O2, stack temperature, efficiency
• Draft and spillage testing at the draft hood or vent connector
• Worst-case depressurization testing, with exhaust fans and the dryer running simultaneously
• Heat exchanger inspection, visually and by combustion signature
• Gas line leak detection on every accessible joint
• Combustion air verification — a frequent problem in houses that have been tightened up

The first two minutes, in order

If an alarm sounds, the sequence matters and it is not the intuitive one. People instinctively open windows and look for the source, and both of those make the situation worse rather than better.

Get out first. Ventilating before you leave prolongs exposure while you do it, and clearing the air makes it harder for responders to measure what was actually present, which affects whether the source is correctly identified.

• Get everyone outside into fresh air immediately, including pets
• Do not open windows to ventilate on the way out, and do not hunt for the source
• Call 911 from outside, and say if anyone is confused, drowsy or unconscious
• Do not re-enter for any reason until emergency services say it is safe
• Seek medical attention for anyone with symptoms, even if they improve outdoors
• Only once the building is cleared does a combustion inspection become useful

Alarms have an expiry date, and most people miss it

A carbon monoxide alarm is not a smoke alarm with a different label. The sensor inside it degrades chemically whether or not it has ever detected anything, and it stops being reliable on a schedule set by the manufacturer rather than by how the unit looks or whether the test button beeps.

That test button confirms the battery and the sounder. It does not test the sensor. An alarm can pass its own test daily for years after the sensing element has ceased to respond to carbon monoxide.

Check the manufacture date printed on the back of the unit rather than the date you installed it, since units sit in warehouses. Replace at the interval the manufacturer states, and replace the whole alarm rather than the battery when that date arrives.