Most homeowners think comfort problems start on the thermostat.
Mike Sanders knows they actually start on the ceiling.
Electric heat—especially from through-the-wall units, PTACs, and combo systems—creates the most misunderstood vertical air movement of any HVAC equipment. Unlike compressors, gas furnaces, or heat pumps, electric heat has a fast, high-intensity radiant footprint. That footprint tends to pile up near the ceiling, leaving the lower part of the room—where humans actually live—cooler, heavier, and often slightly humid.
Mike calls this phenomenon “The Heat Rise Trap.”
This long-form article breaks down Mike’s complete system-design approach for preventing stratification, smoothing vertical temperature, stabilizing comfort, and allowing electric-heat wall units to perform like a full central system.
📘 1. Mike’s Core Principle: “Heat Rises. Comfort Doesn’t.”
When homeowners complain that:
-
their feet are cold,
-
the room feels comfortable only near the unit,
-
the thermostat reads warm but they feel chilled,
-
they have stuffy ceilings and drafty floors,
-
or the electric heat “just doesn’t feel right,”
Mike knows what’s happening.
Electric heat produces:
-
high-density warm air concentrated near the output
-
low-pressure cool air accumulating near the floor
-
a vertical imbalance that worsens with room height
-
slow return-flow movement
Comfort isn’t a top-to-bottom phenomenon.
It’s a lowest-occupied-zone phenomenon—usually between 1.5 to 5 feet above the floor.
Mike’s goal is to pull the heat down, not let it swim up to the ceiling where it’s wasted.
📐 2. Why Electric Heat Causes Extreme Stratification
Many heating systems naturally push or pull air in predictable patterns.
Electric heaters, however, behave differently.
🔥 2.1. Electric Heat Is Radiant-Weighted
Even though wall units use fans, the heating element produces intense localized radiant heat that floats upward before the blower fully mixes it.
📈 2.2. The Blower Discharge Is Horizontal, Not Downward
Nearly all wall units throw warm air straight ahead, leaving cooler, denser air near the floor unmoved.
🌀 2.3. Warm Air Gains Speed as It Rises
This creates a “thermal elevator”:
-
Updraft at the unit
-
Ceiling pooling
-
Down-flow only at perimeter walls
🌫️ 2.4. The Floor Zone Acts Like a Cold Sink
Cool air sinks, resists mixing, and forms a “cold plate” at the floor.
🪟 2.5. Windows Intensify Vertical Drift
Cold windows create downward currents that compete with the heater’s output, causing swirling stratification layers.
This combination forms what Mike calls a vertical thermal stack—a layered room that’s warm at the top and chilly at the bottom.
📊 3. Mike’s Vertical Temperature Rule Set
Mike uses three rules that govern how he designs rooms for electric heat:
📏 Rule 1: The ΔVertical Must Be Less Than 4°F
The difference between floor and ceiling temperature should NEVER exceed 4°F.
Above 6–8°F:
-
comfort collapses
-
cycles become inefficient
-
heating bills shoot upward
-
lower humidity gathers near the floor
🌬️ Rule 2: The Unit Must Stir, Not Blast
Electric heat performs best with:
-
medium airflow
-
gentle, continuous mixing
-
low noise-cycle transitions
Fast-blast airflow throws heat to the ceiling even faster.
↙️ Rule 3: Heat Must Be Directed Toward the Poorest Zone
This usually means pointing airflow toward:
-
windows
-
cold walls
-
long room stretches
-
areas farthest from the unit
This “corridor strategy” distributes heat before it rises.
🧭 4. Mike’s Step-by-Step Vertical Heat Strategy
Here’s the full process he uses to control heat rise in any room.
1️⃣ Step One: Identify Vertical Stratification Using 3 Measurements
Mike takes readings with an IR thermometer at:
📍 Floor (1 inch from surface)
Cold zone
Tells Mike the density and temperature of the heaviest air.
📍 Midline (4 feet from floor)
The human comfort zone
This is the true reference temperature.
📍 Ceiling (1 inch from ceiling)
Heat-pooling zone
This warns of stratification severity.
🧪 Mike’s Interpretation Scale
-
0–3°F difference: Perfect
-
4–6°F: Needs optimization
-
7–10°F: Stratified
-
10°F+ Severe stratification (common in electric heat)
Reference:
ASHRAE thermal comfort guidelines – https://www.ashrae.org/technical-resources
2️⃣ Step Two: Correct the Airflow at the Unit
Mike adjusts the air direction, fan speed, and vane angles to fight heat rise.
📐 4.1. Vane Direction
Mike NEVER points heat straight upward.
Instead he uses:
↘️ Down-Angled Throw
Aim the airflow slightly downward to mix floor air.
⇢ Long Horizontal Glide
Aim along long room paths to stretch the warm air mass.
↖️ Window-Directed Throw
Overcome cold radiation on window-facing walls.
🌬️ 4.2. Fan Speed Settings
Low heat mode:
-
keeps warm air near occupants
-
reduces ceiling pooling
Medium heat mode:
-
best mixing
-
stable circulation
High heat mode:
-
avoided unless pre-heating a very cold room
3️⃣ Step Three: Add a Return Flow Path at the Floor
Warm air rises and must be pulled down somehow.
Mike ensures:
-
the door undercut is at least ¾"
-
furniture doesn’t block baseboards
-
return paths remain unobstructed
For stubborn stratification, Mike adds:
🌀 Low-Flow Floor Booster Fans
Placed:
-
under furniture
-
near cold walls
-
beside the unit
These circulate cold air upward gently.
4️⃣ Step Four: Use the “Thermal Loop” Strategy
Mike aims to create a loop, not a line.
How the loop works:
-
Warm air flows outward from the unit
-
It strikes the far wall
-
It rises
-
It flows back across the ceiling
-
It drops along exterior walls
-
It returns to the unit intake
This creates a stable, pressure-balanced loop.
Rooms that fail this become two-zone layers:
-
upper hot zone
-
lower cold zone
5️⃣ Step Five: Fixing High Ceilings & Vaulted Rooms
If the ceiling is above 9 feet, Mike implements:
📉 5.1. Heat-Down Strategy
Aim airflow:
-
downward
-
toward seating
-
along longest lower trajectory
🌀 5.2. Ceiling Destratification Fan (Low RPM Only)
A slow-moving ceiling fan:
-
pushes trapped heat down
-
evens the temperature
-
dramatically lowers electric heating cost
Default Mike setting:
-
Winter mode: reverse
-
Speed: lowest possible
🧱 5.3. Thermal Zoning
Mike sections rooms visually and adjusts airflow to avoid heat stacking.
6️⃣ Step Six: Manage External Cold Loads
Electric heat loses most of its energy to:
-
large windows
-
thin exterior walls
-
open floor plans
-
stairwells
Mike uses these corrections:
🪟 Window Strategy
Angle airflow toward the window to:
-
break descending cold currents
-
flatten the convection loop
-
reduce floor chilling
🧱 Cold Wall Strategy
Direct heat along the wall plane to correct stratified drift.
🔌 Adjacent Room Strategy
Use door position to influence return airflow.
📉 5. Mike’s “Ceiling Load Reduction Protocol”
Heat rising isn’t the problem—heat staying up there is.
Mike uses:
-
slower fan cycles
-
longer continuous heat runs
-
downward throw angles
-
floor returns
-
ceiling-fan reversal
This stabilizes the entire column of air.
📊 6. Diagnosing Persistent Vertical Problems
Mike checks:
🌡️ 6.1. ΔT at Output vs. Room Temperature
If the unit’s temperature drop is normal but comfort is low, stratification is the real issue.
🎯 6.2. Ceiling Microclimate
Ceiling temperatures 10–15°F higher than midline are wasting electricity.
🧯 6.3. Humidity Gradient
Lower humidity at floor level = stagnant cold air.
Reference:
EPA humidity guidelines – https://www.epa.gov/mold
🪟 6.4. Window Downdraft Strength
Cold window surfaces cause a waterfall of downward air.
🛠️ 7. Mike’s Fixes for Real-World Problem Rooms
🧊 Problem: Cold Floors, Warm Ceilings
Cause: No return airflow
Fix: Add floor booster fan + adjust vane angle down
🔥 Problem: Unit Runs Hot But Room Feels Cool
Cause: Ceiling heat-stacking
Fix: Ceiling fan in reverse mode + medium fan speed
🪑 Problem: Stratification Behind Furniture
Cause: Blocked convection path
Fix: Pull furniture 2–3" off wall
🪟 Problem: Cold Windows Killing Heat
Cause: Radiant downdraft
Fix: Aim airflow toward window or run micro-fan at sill
⚡ 8. Performance Gains When Heat-Rise Is Corrected
Mike regularly sees:
-
20–45% reduced electric heating cost
-
up to 60% faster warm-up times
-
smoother, more even temperature from floor to ceiling
-
less dryness and hot-air feeling
-
significant improvement in cold-floor comfort
-
more stable thermostat behavior
Electric heat goes from feeling “dry and weak” to “soft, warm, and stable.”
🔗 External Verified Sources (Max 6)
-
DOE Insulation & R-Value Overview
https://energy.gov/energysaver/weatherize/insulation -
FLIR – Thermal Imaging Basics
https://www.flir.com/discover -
EPA Moisture & Mold Control
https://www.epa.gov/mold -
Window & Door Flashing Principles (relevant to sleeve flashing)
https://www.energy.gov/energysaver/design/windows-doors-and-skylights -
ACCA Manual J Load Guidelines
https://www.acca.org/hvac-design/manual-j
