Audit your carbon monoxide detector coverage
One-time · any month works
Why it matters
Your heat comes from burning fuel, which means your house makes carbon monoxide on purpose all winter and exhausts it on purpose — until something interferes: a cracked heat exchanger, a blocked flue, a backdrafting water heater sharing the chimney.
Cars in attached garages round out the big three sources. The audit takes twenty minutes and the coverage rules are short.
What skipping it costs
$0–$10,000
Carbon monoxide is the failure you don't get feedback on — no smell, no smoke, symptoms that read as the flu. The priced part is an ER visit and hyperbaric treatment; the rest isn't priced. Your furnace burns fuel all winter on the other side of a heat exchanger — the detector is the only witness if that barrier fails.
Two ways to get it done
Do it yourself
You'll need: Step stool, UL-listed CO detectors as needed (~$25–$50 each).
- Count what you have and where. The coverage floor: one CO detector on every level of the house, one within earshot of each sleeping area, and one near (not inside) the door to an attached garage.
- Check ages — CO sensors expire faster than smoke sensors, typically 5–7 years. The date's on the back; expired units get replaced, not batteries.
- Placement details that matter: CO mixes with air, so wall or ceiling both work. Keep units 15+ feet from the furnace and gas range to avoid nuisance readings, and out of dead-air corners.
- Don't mount one directly in the furnace closet expecting an early warning — you want detectors where people breathe, not where the machine lives.
- If any alarm ever sounds: out of the house first, count heads, call from outside. The fire department's meter — not your nose — decides when it's over.
Hire it out
$120–$250National fair range — local labor moves this number.
There's no real service call here — this is a hardware-store errand. If you want a pro involved, a $120–$250 visit makes sense only bundled with something real, like a combustion analysis on the furnace, which pairs naturally with your fall heating checkup.
The scam to know: a tech "detects CO" during an unrelated visit and the furnace is suddenly condemned. Real CO diagnosis produces numbers — ppm readings at specific locations, a combustion analysis printout. No numbers, no new furnace. Get the reading or get a second opinion.
Ask the tech
- If you're telling me there's CO, what did your meter read, in ppm, and where?
- Combination smoke/CO units or standalone — and why for my layout?
- Where's the CO most likely to come from in this house — furnace, water heater, or garage?
Red flags you're being upsold
- A 'CO leak' pronouncement with no ppm reading shown. CO diagnosis is a number, not a feeling.
- A furnace-replacement pitch built on a CO scare without a documented combustion analysis.
- Pushing $150+ low-level monitors on every floor when $40 UL-listed units meet the need for most homes.
Second opinion time: Any 'shut it down, replace the furnace today' call — a second combustion test costs $150 and settles it with numbers.
The call
DIY this today — it's twenty minutes of counting and a trip to the hardware store. There's nothing here to hire.