Sewer Odor, a Silenced CO Alarm, and a Scorched Draft Hood
A technician is called to a 1962 ranch home in Pueblo to replace a dripping kitchen faucet. In the basement she finds a strong sewer odor near the laundry, a floor drain that is bone dry, and damp staining on the slab around it. The homeowner mentions that the hallway carbon monoxide alarm chirped twice last week and was silenced because "it was probably a low battery." In the corner of the same alcove sits a 40-gallon atmospheric water heater behind a solid, weatherstripped door with no combustion-air openings; the draft hood shows corrosion and there is scorching on the wall above it. The homeowner wants the faucet finished today and asks whether the other items can wait until spring.
1. What do you do before you open the faucet box, and why that order?
Read the worked answer
The faucet is a convenience repair; the CO evidence is a life-safety emergency, so it controls the sequence.
- Stop and vent. Open the basement door/windows, shut the water heater off (gas valve and control, if qualified to do so - otherwise the gas utility), and tell the homeowner plainly that the alarm was telling them something. A chirping alarm that was silenced is not evidence of a low battery.
- Do not leave the appliance operating. Scorched wall above a draft hood plus a weatherstripped door with no combustion air is a classic spillage setup: the burner consumes room air, the closet depressurizes, and flue gases spill at the hood instead of rising.
- Confirm rather than assume. Use a combustion analyzer or a spillage test (smoke/match at the hood with the door closed and the dryer or bath fan running) before anyone mentions relighting.
- Document and hand off. Tag the appliance, note findings on the invoice, and advise the homeowner to call the gas utility and the local authority; the faucet can be finished afterward if the home is safe.
2. How do you determine whether the floor drain is the whole odor story, and what distinguishes a lost trap seal from a venting failure?
Read the worked answer
A dry trap and a blocked vent can both smell, but they behave differently and the fix is different.
- Re-prime and watch. Pour a bucket of water into the drain. If the odor fades for days and returns, the trap seal is evaporating - the drain is unused, or a trap primer was never installed or has failed. A floor drain in a laundry area needs a maintained seal (primer or a listed trap seal device).
- Look for pressure-driven loss. If the drain gurgles when the washer or a nearby fixture discharges, or if water is sucked out of the trap, the vent is restricted or the branch is wet-venting incorrectly; the trap is being siphoned, not just drying out.
- Test the system, not the smell. A smoke test on the DWV will reveal a broken drain line under the slab (consistent with the damp staining) that no amount of re-priming will fix. Camera the line if the smoke test is inconclusive.
- Check the whole stack. Roof-side blockage (bird nest, collapsed cap) is common on a 1962 home and produces gurgling plus odor in several fixtures, not just one.
3. What should be in writing, and who gets notified?
Read the worked answer
Write it the way you would want it read in a claim file:
- Red tag / do-not-operate on the water heater, with the reason (spillage evidence, no combustion air, corroded draft hood).
- Invoice language that separates the work you performed from the hazards you observed and referred: sewer odor with a dry trap and a possible under-slab break; CO alarm history; inadequate combustion air.
- Notification to the homeowner in person (and by email/text if available), with the recommendation to contact the gas utility and to have the venting and combustion air corrected by a qualified party before the appliance is returned to service.
- Do not relight or return the unit to service on the strength of a verbal assurance, and do not let the faucet repair become the reason the safety findings were never recorded. If the appliance remains unsafe and the occupant stays, escalating to the utility or building department is the defensible choice.