If your Reznor heater is the heart of your shop, the burner and flame assembly is the pulse. When it’s clean, aligned, and breathing right, you get fast heat, clean combustion, and low fuel waste. When it’s dirty or neglected? You’ll see yellow flames, delayed ignition, soot buildup, and propane bills that make no sense.
I’ve seen perfectly good Reznor heaters get blamed for “old age” when the real problem was five years of dust, spider webs, and ignored burner ports.
Reznor UDX 60,000 BTU Propane Unit Heater
This guide walks you through a proper burner and flame tune-up—what to clean, what to inspect, what to adjust, and when to stop and call a pro.
🧯 Safety First: Read This Before Touching Anything
Before you crack the cabinet:
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Turn OFF electrical power at the disconnect
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Shut OFF the propane supply
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Allow the unit to cool completely
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Wear gloves and eye protection
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Never modify gas orifices or safety controls
If you smell propane at any point—stop, ventilate, and do not proceed.
🧰 Tools You’ll Need for the Job
You don’t need a service truck, but you do need the right basics:
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Nut drivers or socket set
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Soft wire brush (brass preferred)
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Compressed air or shop vacuum
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Flashlight or headlamp
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Small mirror
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Fine grit emery cloth (for flame sensor)
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Soap/water solution (gas leak test)
Optional but helpful:
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Combustion analyzer (pro-level)
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Manometer (for gas pressure checks)
🔍 Step 1: Access the Burner Compartment
Remove the front service panel carefully.
Inside you’ll typically see:
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Burner tubes
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Gas manifold
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Igniter
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Flame sensor
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Heat exchanger inlet
What to look for immediately:
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Dust buildup
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Rust flakes
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Spider webs (very common)
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Signs of overheating or discoloration
If everything looks filthy, you’re in the right place.
🔥 Step 2: Inspect the Burner Tubes
Burners need clean, open ports to mix air and propane correctly.
Inspect for:
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Blocked burner slots
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Rust scale inside tubes
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Bent or warped metal
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Misalignment with the heat exchanger openings
Common issues I see:
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Burners half-blocked by dust and debris
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Spider nests in unused heaters
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Burners shifted from vibration
Action:
Remove the burners if the design allows. Brush them gently and blow compressed air through the ports. Never use water.
🔗 Combustion fundamentals (EPA):
https://www.epa.gov/indoor-air-quality-iaq
🧹 Step 3: Clean the Burner Orifices (Carefully)
The orifice meters propane flow. It is precision-sized.
Do NOT:
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Drill
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Ream
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Enlarge
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Force wire into it
What you should do:
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Remove orifice if accessible
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Blow compressed air through it
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Inspect visually for debris
If an orifice is damaged or clogged beyond cleaning, replace it—don’t improvise.
🔌 Step 4: Inspect and Clean the Igniter
A weak igniter causes delayed ignition or no ignition at all.
Check for:
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Cracks in ceramic
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Carbon buildup
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Loose mounting screws
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Proper positioning near the burner
Action:
Gently clean with compressed air. Replace if cracked or heavily worn.
Delayed ignition isn’t just annoying—it can damage burners over time.
🔍 Step 5: Clean the Flame Sensor (Huge Payoff)
This little rod shuts down heaters more than any other part.
Symptoms of a dirty flame sensor:
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Heater lights, then shuts off
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Short cycling
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Lockouts with no obvious cause
How to clean it:
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Remove the sensor
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Lightly polish with fine emery cloth
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Wipe clean—no solvents
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Reinstall securely
That’s a five-minute job that saves service calls.
🔗 Flame sensing explanation:
https://www.energy.gov/energysaver/furnaces-and-boilers
🌬️ Step 6: Check Combustion Air Openings
Burners need oxygen. Restricted air = dirty flames.
Inspect:
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Combustion air openings
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Intake piping (if applicable)
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Screens for dust or debris
Signs of air starvation:
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Yellow or lazy flames
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Soot buildup
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Smell of combustion byproducts
Clear all obstructions and verify nothing has been stored too close to the heater.
🔥 Step 7: Reassemble & Perform a Flame Test
Restore power and gas.
Call for heat and watch the flame.
A healthy Reznor flame should be:
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Mostly blue
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Stable and consistent
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Even across all burners
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No lifting or fluttering
Problem flames include:
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Yellow tips → dirty burners or air issues
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Lifting flames → airflow or pressure problem
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Uneven flames → blocked ports or misalignment
🔗 Propane flame characteristics:
https://propane.com/propane-safety-in-your-home/
📏 Step 8: Verify Proper Burner Alignment
Burners must line up cleanly with heat exchanger inlets.
Misalignment causes:
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Flame roll-out
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Overheating
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Reduced efficiency
If burners don’t seat squarely, loosen mounts and realign before tightening.
This step is often skipped—and it matters.
⚠️ Step 9: Check for Signs You Should Stop
Stop DIY work and call a professional if you see:
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Cracked heat exchanger inlet
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Flame rollout
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Persistent yellow flames after cleaning
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Gas pressure issues
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Repeated ignition failures
Burner tuning is maintenance—not modification.
🧠 Pro Tip: Why Burner Maintenance Saves Propane
Dirty burners don’t just burn ugly—they burn inefficiently.
Clean burners:
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Light faster
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Burn more completely
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Reduce run time
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Lower carbon buildup
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Extend heat exchanger life
That’s less propane burned and less stress on the system.
🔗 Heating efficiency overview:
https://www.energystar.gov/products/furnaces
🗂️ Step 10: Document What You Did
Write it down:
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Date cleaned
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Burner condition
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Flame appearance
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Parts replaced
This helps spot patterns and protects warranties.
🔗 Manufacturer reference (Reznor):
https://www.reznorhvac.com
🏁 Final Word from Tony
Burners don’t fail overnight—they get dirty slowly until performance drops and problems stack up.
If you tune the burner and flame assembly once a year, your Reznor heater will:
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Start cleaner
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Run quieter
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Burn less propane
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Last longer
Five percent effort here prevents eighty percent of heating problems later.
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In the next topic we will know more about: Fan, Blower, and Motor Care: The Quiet Workhorse of Your Propane Heater
