How to Test Smoke and Carbon Monoxide Detectors — Iowa
Complete checklist with climate-adjusted recommendations for Iowa
Overview
Replace batteries, test alarm function, replace units older than 10 years (smoke) or 7 years (CO).
Step-by-Step Guide
Locate every detector in your home
Walk through every room and note the location of each smoke detector, CO detector, and combination unit. Minimum recommended placement: one on every level of the home, inside each bedroom, outside each sleeping area, and near (not inside) the kitchen and garage. Most homes should have at least 5–8 units.
Check manufacture dates
Remove each detector from its mounting plate and look for the manufacture date printed on the back. Smoke detectors should be replaced after 10 years. CO detectors should be replaced after 5–7 years (check manufacturer recommendation). Combination units follow the shorter lifespan. If there is no date visible, replace the unit.
Replace batteries in all units
Even in hardwired detectors, replace the backup batteries annually. Most units use 9-volt or AA batteries. Use high-quality alkaline or lithium batteries — lithium batteries last up to 10 years in low-drain devices. After inserting fresh batteries, the unit should chirp once to confirm power. Never use rechargeable batteries in smoke detectors.
Test the alarm function
Press and hold the test button on each unit for 3–5 seconds. The alarm should sound loudly within a few seconds. If the sound is weak or the alarm does not sound at all, try replacing the battery first. If it still fails, replace the entire unit. Test one detector at a time and alert household members first.
Verify interconnection
If your detectors are hardwired and interconnected, triggering one should set off all connected units in the house. Press the test button on one detector and walk through the house listening for the others. If they do not all sound, check wiring connections or replace the non-responding unit.
Clean each detector
Dust, cobwebs, and cooking residue can interfere with detector sensors. Vacuum the exterior of each unit with a soft brush attachment. For stubborn residue, use a can of compressed air to blow out the sensing chamber. Do not use water, cleaners, or solvents on detector units.
Replace expired or failed units
Mount new detectors on the ceiling or high on the wall (within 12 inches of the ceiling). For ceiling mounting, place them at least 4 inches from the nearest wall. Avoid placing detectors within 3 feet of HVAC registers, ceiling fans, or bathroom doors (steam causes false alarms). Follow the manufacturer's instructions for the mounting bracket.
What You'll Need
Tools
- - Step ladder
- - Screwdriver (for hardwired units)
- - Vacuum with soft brush attachment
- - Compressed air (optional)
Materials
- - Replacement batteries — 9V or AA ($5–$10 for a pack)
- - Replacement detectors if expired ($20–$40 each for combination smoke/CO units)
Cost Estimates
DIY Cost
$10–$50 (batteries and 1–2 replacement units if needed)
Professional Cost
$150–$400 for an electrician to install hardwired interconnected detectors throughout a home
Safety Tips
- Turn off the circuit breaker before disconnecting hardwired detectors to avoid electrical shock.
- Never disconnect a chirping detector and leave it uninstalled — that chirp means low battery, not a malfunction.
- After cooking smoke triggers a false alarm, do not remove the battery. Instead, fan the detector or press the silence/hush button.
- Have an escape plan — testing detectors is a good time to review and practice your family's fire escape plan.
When to Call a Professional
Call an electrician if you need to install hardwired, interconnected detectors throughout your home, if existing hardwired units are not triggering each other, or if you are unsure about the wiring. Many municipalities require hardwired, interconnected smoke detectors for home sales or renovations.
Pro Tip
Write the installation date on the side of each detector with a permanent marker when you install it. This way you never have to remove it and squint at the back label to check the date — you will know at a glance when it is due for replacement.
Common Mistakes to Avoid
- Testing detectors by blowing cigarette smoke or holding a match near them — use the test button instead.
- Installing detectors in the wrong locations, such as inside kitchens (excessive false alarms) or in garages (temperature extremes damage sensors).
- Assuming that hardwired detectors do not need battery replacement — the backup battery is critical during power outages.
- Removing a chirping detector at 2 AM and forgetting to replace the battery the next day.
- Not replacing the entire unit after 10 years — the sensor degrades internally even if the alarm still sounds during a button test.