Understanding Heating or Cooling DelaysUpdated 10 hours ago
When your heating or cooling doesn’t turn on right away, it can be frustrating — but in most cases, it’s completely normal. Your Mysa thermostat uses built-in protection features and comfort-balancing rules to keep your HVAC system healthy and your home energy efficient.
This article explains the most common reasons you may experience a delay in heating or cooling.
1. Minimum Compressor Off Time (MCOT)
Applies to: Heat pumps and air conditioners only
Mysa MCOT: 5 minutes
What It Is
After heating or cooling turns off, your thermostat enforces a mandatory “rest” period before the system can start again. This is often referred to as a compressor lock-out. It allows system pressures to equalize and internal components to return to safe operating conditions.
How It Causes Delays
If your HVAC system recently shut off, it will not turn back on immediately—even if the room temperature calls for it—until the 5-minute MCOT has passed.
During this period, the heating or cooling icon will appear on the thermostat or in the app, but the system won’t engage until the lock-out expires.
Why It Matters
Turning the compressor on too soon after it shuts off can cause it to operate under high internal pressure, leading to strain and possible damage. The 5-minute delay protects your system by allowing it to restart safely.
2. Cycles Per Hour (CPH) Limits
Applies to: All HVAC systems supported by Mysa for Central HVAC
Mysa CPH Settings:
12 for electric systems
6 for fuel-based systems
3 for heat pump or hydronic systems
What It Is
CPH limits how many times your system can turn on in a single hour. This prevents short-cycling, which is when a system turns on and off too frequently.
How It Causes Delays
Even if heating or cooling is needed, Mysa may delay the next cycle if the maximum allowed cycles per hour has already been reached.
Example:
System Type: Heat Pump
CPH Limit: 3 (1 cycle every 20 minutes)
If a cycle starts at 1:00 PM and ends at 1:10 PM, and another call for heat happens at 1:16 PM, the system will wait until 1:20 PM before starting the next cycle.
Note: Manual temperature adjustments override CPH limits. This is useful during setup, maintenance, or troubleshooting.
Why It Matters
CPH limits reduce system wear and tear, improve temperature stability, and lower energy consumption.
3. Temperature Differential (Swing)
Applies to: All HVAC systems supported by Mysa for Central HVAC
Mysa Differential: 1°F (0.6°C)
What It Is
To avoid unnecessary cycling, Mysa thermostats use a temperature differential (also called a swing or deadband). The system won’t turn on with tiny fluctuations in temperature.
How It Causes Delays
Heating or cooling will only activate once the room temperature moves sufficiently away from the setpoint.
Example:
Setpoint: 21°C
Differential: 0.6°C
Heating may not activate until the room drops to 20.4°C.
This can feel like a delay, especially when temperature changes rapidly.
Why It Matters
This feature prevents frequent cycling, reduces energy use, and helps maintain consistent comfort levels.
4. Combined Effects
Sometimes, more than one delay rule applies at the same time. For example:
The room temperature exceeds the differential threshold, but
The compressor is still in its Minimum Off Time, or
The system has reached its CPH limit.
Why This Happens
These overlapping protections are intentional. While they can make delays seem longer than expected, they ensure safe operation, prevent equipment strain, and optimize energy efficiency.
If you're still unsure whether your delay is normal or you're experiencing issues outside of these conditions, consider contacting our support team for further troubleshooting.