421-331 Allanson Lennox Ignition Transformer

The Allanson 421-331 ignition transformer is a high-reliability, double pole unit designed specifically for Lennox oil burners. With a powerful 10,000V secondary and 120V primary input, this transformer ensures consistent ignition performance under demanding operating conditions. Built with high-temperature wire and designed to manufacturer specifications, the 421-331 provides long service life, quieter operation, and dependable ignition power.

✅ Key Features

• Built with high-temperature wire for durability and extended service life

• Runs cooler, quieter, and safer on oil burners

• Manufactured to Lennox OEM specifications for guaranteed fit and performance

• Meets American & European EMI/RFI noise emission standards

• Single porcelain design for durability and stability

• Provides dependable ignition source for commercial and residential oil burner applications

📊 Technical Specifications

⚠️ Common Symptoms of a Failing Ignition Transformer

• Burner fails to ignite or takes multiple attempts

• Intermittent ignition or weak spark

• Sparking noise but no flame established

• Soot buildup from incomplete combustion

• Repeated lockouts requiring manual resets

• Visible cracks, burns, or arcing on transformer casing or terminals

🛒 Shopping Tips – How to Choose the Right Replacement

1. Match the Primary Voltage → This model is 120V input; check your burner’s rating.

2. Secondary Voltage & Current → Ensure compatibility with 10,000V @ 23mA ignition requirements.

3. Grounding Type → The 421-331 uses mid-point ground; incorrect grounding may prevent proper ignition.

4. HV Terminal & Mounting → Designed with a zinc plated button terminal and end hinge mount.

5. OEM Compatibility → Built for Lennox oil burners; verify burner type for proper fit.

6. Replace Proactively → If your transformer shows signs of wear, replacing early helps avoid downtime.

❓ Frequently Asked Questions (FAQ)

Q1: Is this transformer specific to Lennox burners?
Yes, it is designed to Lennox OEM specifications but may also fit other burners requiring the same electrical ratings.

Q2: What is the output voltage?
The secondary output delivers 10,000V at 23mA for reliable ignition.

Q3: Can I use this as a universal replacement?
It is best suited for Lennox applications, but if the specs match (voltage, grounding, and terminal type), it can be used as a replacement.

Q4: Does it reduce electrical noise?
Yes — it meets EMI and RFI standards, preventing interference with nearby equipment.