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Page 6 - FLAME SENSORS

# Flame Sensors - Furnace Flame Rods and Detectors

Shop replacement flame sensors (flame rods) for gas furnaces. We stock flame sensors for all major HVAC brands including Carrier, Trane, Lennox, Goodman, and more at our Westland, Michigan warehouse, ready to ship same-day.

## Why Buy Flame Sensors From Technical Hot & Cold?

**Complete Sensor Selection**
Flame sensors for virtually every gas furnace make and model, from budget-friendly to premium brands.

**OEM Quality**
Genuine manufacturer flame sensors ensure proper fit, function, and safety compliance.

**Same-Day Shipping**
Flame sensors in stock ship today when ordered before 3PM EST from our Westland warehouse.

**Low-Cost Safety Part**
Flame sensors are inexpensive but critical safety components. Stock up and keep one on hand!

## What is a Flame Sensor?

The flame sensor (also called flame rod or flame probe) is a safety device that:
- Detects presence of flame at burners
- Proves safe combustion before continuing
- Shuts off gas valve if flame is lost
- Prevents dangerous gas buildup
- Required on all modern furnaces with electronic ignition

**Located:** Positioned in flame path at burners
**Function:** Flame detection and safety monitoring

**How It Works:**
- Flame conducts small AC current through sensor
- Control board monitors this current (microamps)
- Adequate signal = safe to continue
- No signal = shut off gas (safety lockout)

## Flame Sensor Specifications

### Physical Specifications:

**Rod Material:**
- Stainless steel or ceramic
- Corrosion-resistant
- High-temperature rated

**Rod Length:**
- 2" to 5" typical
- Must reach into flame
- Varies by furnace model

**Mounting:**
- 1/4" hex head (most common)
- Bracket mount
- Direct thread mount
- Must match original

**Wire Connection:**
- Quick-disconnect
- Screw terminal
- Various configurations

### Electrical Specifications:

**Current Signal:**
- 0.5 to 10 microamps typical
- Must be above minimum threshold
- Varies by control board

**Voltage:**
- Part of 24V circuit
- AC signal through flame
- Rectification by flame

## Common Flame Sensor Problems

### Furnace Symptoms:

**Ignites Then Shuts Off:**
- Most common symptom
- Ignitor glows, burners light
- After 3-10 seconds, shut off
- Repeated attempts
- Eventually lockout

**Won't Stay Running:**
- Same symptoms as above
- "Short cycling" on ignition
- Frustrating for homeowners
- Usually easy fix

**Error Code Displayed:**
- LED flashes specific pattern
- Indicates "flame sensing error"
- Consult furnace manual
- Most boards have diagnostic LEDs

### Causes of Flame Sensor Issues:

**Dirty Sensor (Most Common):**
- Carbon buildup on rod
- White oxidation coating
- Prevents current flow
- Simple cleaning fixes

**Cracked Ceramic:**
- Physical damage
- Allows grounding
- Cannot be repaired
- Must replace

**Corroded Connection:**
- Wire connection oxidized
- Poor electrical contact
- Clean or replace

**Wrong Position:**
- Not in flame path
- Bent or misaligned
- Recently serviced/moved
- Reposition correctly

**Bad Sensor:**
- Less common than dirty
- Actual sensor failure
- Replace with new

## Flame Sensor Cleaning

**You can often fix the problem without replacement!**

### Cleaning Procedure:

**What You Need:**
- Fine grit sandpaper or emery cloth (400-600 grit)
- Clean cloth
- Screwdriver (usually 1/4" hex)

**Steps:**

1. **Turn Off Power**
   - Breaker and furnace switch
   - Wait 5 minutes
   - Ensure no power

2. **Access Burner Compartment**
   - Remove front panel
   - Remove burner access cover
   - Locate flame sensor (rod near burners)

3. **Remove Flame Sensor**
   - Unplug wire connection
   - Remove mounting screw (1/4" hex usually)
   - Carefully slide out of bracket

4. **Inspect Sensor**
   - Look for carbon buildup (black)
   - Look for white oxidation
   - Check for cracks in ceramic

5. **Clean the Rod**
   - Use fine sandpaper/emery cloth
   - Gently rub rod surface
   - Don't scrub aggressively
   - Clean entire exposed metal
   - Wipe with clean cloth
   - Rod should be shiny metal

6. **Reinstall Sensor**
   - Slide back into bracket
   - Position in flame path
   - Secure mounting screw (don't overtighten!)
   - Reconnect wire

7. **Test Furnace**
   - Restore power
   - Call for heat
   - Verify ignition and continuous operation
   - Monitor several cycles

**Cleaning Tips:**
- Don't use steel wool (too abrasive)
- Don't use chemicals
- Don't bend the rod
- Don't scratch ceramic insulator
- Handle carefully

**How Often:**
- Clean annually during maintenance
- More often if needed
- Preventive maintenance extends life

## Flame Sensor Replacement

**When to Replace:**
- Cleaning doesn't fix problem
- Cracked ceramic insulator
- Corroded beyond cleaning
- Bent rod
- Preventive replacement

**Installation Steps:**

1. **Turn Off Power**
   - Breaker and furnace switch
   - Verify no power

2. **Remove Old Sensor**
   - Follow cleaning steps above
   - Unplug wire
   - Remove mounting screw
   - Extract sensor

3. **Compare New to Old**
   - Match rod length
   - Match mounting style
   - Verify wire connection type

4. **Install New Sensor**
   - Insert in mounting bracket
   - Position same as old sensor
   - Rod must be in flame path
   - Secure mounting screw
   - Connect wire firmly

5. **Verify Position**
   - Rod tip should be in burner flame
   - About 1/2" into flame path
   - Not touching burners
   - Proper spacing

6. **Test Operation**
   - Restore power
   - Call for heat
   - Verify ignition
   - Burners should stay lit
   - Monitor several cycles

## Flame Sensor Positioning

**Critical for Proper Operation:**

**Proper Position:**
- Rod extends into flame path
- About 1/2" into flame
- Not touching burners
- Not too far from burners
- Same position as original

**Poor Position:**
- Too far from flame
- Not in flame path
- Touching burner (grounds out)
- Bent away from flame

**After Cleaning/Replacement:**
- Verify position before closing
- Watch first ignition cycle
- Ensure rod is in flame
- Adjust if necessary

## Troubleshooting After Replacement

**Still Won't Stay Running:**

**Check These:**
1. **Wire Connection**
   - Firmly connected?
   - Corroded terminal?
   - Clean and reconnect

2. **Sensor Position**
   - In flame path?
   - Proper distance?
   - Reposition if needed

3. **Burners Clean?**
   - Dirty burners = poor flame
   - Yellow flame = problem
   - Clean burners if needed

4. **Grounding Issue**
   - Sensor touching metal?
   - Damaged insulator?
   - Check carefully

5. **Control Board**
   - If sensor is good, board may be bad
   - Less common
   - Professional diagnosis

**Measure Flame Current:**
- Use microamp meter
- Measure signal at control board
- Should be 0.5-10 microamps
- Below threshold = problem
- Helps diagnose issue

## Flame Sensor Maintenance

**Preventive Maintenance:**
- Clean annually
- Inspect during service
- Check wire connection
- Verify proper position
- Keep burner area clean

**Extend Sensor Life:**
- Annual cleaning
- Clean burners regularly
- Change filter monthly
- Proper combustion air
- Address problems promptly

## Flame Sensor FAQs

**Q: How often should I replace my flame sensor?**
A: Can last 10-20 years if maintained. Replace when cleaning no longer works or if damaged.

**Q: Can I clean my flame sensor?**
A: Yes! This is the most common fix. Use fine sandpaper, clean gently. Often solves the problem immediately.

**Q: Why does my flame sensor get dirty?**
A: Normal combustion deposits. Accelerated by:
- Dirty burners
- Improper air/fuel mixture
- Dirty filter
- Lack of maintenance

**Q: Is a flame sensor the same as a thermocouple?**
A: No. Thermocouples are for standing pilot furnaces. Flame sensors are for electronic ignition furnaces. Different function and technology.

**Q: Can I bypass the flame sensor?**
A: NEVER! Flame sensors are critical safety devices. Bypassing creates extreme danger - gas buildup, explosions, death.

**Q: How do I know if my flame sensor is bad vs dirty?**
A: Try cleaning first. If cleaning doesn't work, likely bad. Cracked ceramic = definitely bad.

**Q: What current should my flame sensor show?**
A: Typically 0.5 to 10 microamps. Varies by control board. Check manufacturer specs. Below minimum = shutdown.

**Q: Can I use any flame sensor?**
A: Best to use exact replacement. Some universal sensors work but OEM-specific is always safest for proper fit and function.

**Q: Why did my new flame sensor fail quickly?**
A: Possible causes:
- Dirty burners (clean them!)
- Poor combustion (needs adjustment)
- Wrong position (reposition)
- Rare: defective sensor

**Q: How much does a flame sensor cost?**
A: Typically $15-40. Very inexpensive for such a critical safety part. Worth keeping a spare!

## Signs You Need a New Sensor

**Replace If:**
- Cleaning doesn't solve problem
- Cracked ceramic insulator
- Bent rod (can't straighten properly)
- Heavy corrosion/pitting
- Multiple cleaning cycles per season needed

**Test First:**
- Try thorough cleaning
- Check positioning
- Verify wire connection
- Measure microamp signal

## Compatible with All Major Brands

**We Stock Sensors For:**
- Carrier / Bryant
- Trane / American Standard
- Lennox
- Goodman / Amana
- Rheem / Ruud
- York / Coleman
- Heil / Tempstar
- Armstrong
- Payne
- And many more!

## For HVAC Contractors

**Stock Your Service Vehicle:**
- Inexpensive to stock
- Common failure item
- Quick fix = happy customer
- Multiple brand/model sensors

**Bulk Pricing:**
- Volume discounts available
- Mix and match models
- Keep full inventory

## Need Help Selecting a Flame Sensor?

Our HVAC parts specialists are here to help! Contact us:
- **Phone:** [Your phone number]
- **Email:** [Your email]
- **Hours:** [Your business hours]
- **Location:** Westland, MI - Local pickup available

**Have your furnace model number ready for exact match. Many sensors look similar but have different specifications!**

Can't find what you're looking for?

If you don't see your model or part, call us! Our friendly technicians are standing by. We can help you find the part you need with guaranteed fitment. Speak with us today at (734) 326-3900.

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