Understanding Wall Draft and How It Affects Your Mysa for Central HVACUpdated 18 days ago
Overview
If your Mysa thermostat seems to be displaying inaccurate temperature or humidity readings, wall draft may be the culprit. This article explains what wall draft is, how it impacts thermostat performance, and what you can do to fix it.
What Is Wall Draft?
Wall draft occurs when air is unintentionally pulled through a gap or cavity behind your thermostat—typically near an HVAC return vent. This can happen if your thermostat is installed:
Near a return air vent
On a wall that backs onto a return duct
Over an unsealed hole where wires come through the drywall
When your HVAC system turns on, it pushes air into your home while pulling stale air out through return vents. That old air may travel through wall cavities—like the space between wall studs—passing behind your thermostat. If there's an open hole in the wall for wires, this air can escape through the hole and affect your thermostat's sensors.
How Wall Draft Affects Your Mysa Thermostat
Wall draft can lead to inaccurate readings that make your Mysa think the room is warmer or cooler than it actually is. Here's how it typically affects performance:
During heating: Cooler air pulled through the wall cavity may make the thermostat think the room is colder than it is. This can cause your system to heat for longer than necessary.
During cooling: Warmer or more humid air behind the wall can make it seem like the room is hotter or more humid, also leading to longer runtime.
This misreading may result in discomfort or energy inefficiency if the system runs more than it should.
Signs You Might Be Experiencing Wall Draft
If you're seeing inconsistent or incorrect temperature and humidity readings, look out for these clues:
The thermostat reading is consistently different from another trusted device (like a room sensor or digital thermometer).
The reading seems fine sometimes, but becomes inaccurate when heating or cooling starts.
Temperature or humidity rises after the HVAC system turns on (instead of decreasing, which is expected with cooling).
This behavior may indicate that external air (not room air) is affecting the thermostat sensor.
Diagnosing Wall Draft with Your Mysa
If you're troubleshooting temperature inconsistencies, try the following:
Compare readings: Use another accurate thermometer or room sensor in the same room.
Check runtime patterns: If the room seems to be heating or cooling more than expected, it could be due to false readings.
Inspect thermostat location: Is it near a return vent or directly on the other side of a wall that might contain ductwork?
Mysa Support can also help you interpret your runtime data to look for patterns typical of wall draft behavior.
How to Fix Wall Draft
The good news: fixing wall draft is simple.
Seal the hole behind your thermostat.
You can use plumber’s putty or similar insulating material to block airflow coming through the wall cavity.
Steps:
Turn off power to the thermostat.
Remove the faceplate.
Gently push plumber’s putty into the hole where the wires come through.
Reattach the faceplate and restore power.
By sealing the wall cavity, you’ll prevent external air from skewing your thermostat readings, improving accuracy and overall system performance.