Water-producing equipment around a typical furnace
| Equipment | Where the water goes | Common failure | Season |
|---|---|---|---|
| Whole-house humidifier | Small tube to a floor drain or condensate pump | Scale-clogged pad or drain, stuck solenoid valve | Heating season |
| High-efficiency furnace | Condensate line, often to a pump | Clogged trap, cracked fitting, failed pump | Heating season |
| Central AC coil | Condensate pan and line to drain or pump | Algae in the line, rusted pan | Cooling season |
| Condensate pump | Lifts water to a sink or drain line | Float sticks, motor fails, discharge tube kinks | Year round |
| Water heater | Relief valve discharge tube | Valve drips from high pressure or age | Year round |
Why these leaks get missed
A humidifier or condensate leak rarely makes a puddle you trip over. It is a steady trickle, sometimes a few cups a day, running under the furnace platform and wicking into the carpet or the bottom of the drywall in the next room. In many Highlands Ranch basements the mechanical room shares a wall with a finished family room or bedroom, so the first sign is a damp carpet edge or a stain along the baseboard.
Hard water makes humidifiers worse. Minerals build up on the pad and in the drain fitting until water backs up and finds another path out. A failed solenoid valve can also let water run continuously, even when the furnace is idle.
What to do when you find water by the furnace
- Turn the humidifier water off.There is usually a small saddle or quarter-turn valve on the copper or plastic feed line. Close it.
- Check the pump.If a condensate pump is full and not running, unplug it before handling it and empty the reservoir.
- Look for the path.Follow the wet area back to the source. Water under the furnace may come from the AC coil pan above it.
- Feel the next room.Check carpet and baseboard on the other side of the shared wall. Pull back a corner of carpet if needed.
- Call HVAC, then decide on drying.A heating and cooling technician fixes the drain or pump. If carpet pad or drywall is wet, drying is a separate task.
Twice-a-year mechanical room check
- Replace or clean the humidifier pad at the start of heating season
- Pour a little water into the condensate trap and confirm it drains
- Lift the condensate pump float to confirm the pump runs
- Look for rust stains under the AC coil cabinet
- Make sure drain tubes are not kinked or sagging
- Check the carpet edge in the room next to the furnace
General information for Highlands Ranch, not a quote or professional advice. In an emergency, call 911.