Suburban 525033 Igniter Electrode For NT Series Furnaces

Overview

The Suburban 525033 is a genuine OEM replacement igniter electrode for select NT series Suburban RV furnaces. This 2-prong single electrode performs dual functions: it creates the high-voltage spark to ignite the propane burner AND acts as the flame sensor to verify the burner is lit.OEM Suburban2-Prong

When the thermostat calls for heat, the furnace control board sends high voltage to this electrode, producing a spark at the burner to ignite the propane. Once lit, the electrode uses flame rectification to sense the presence of the flame and send a signal back to the control board. If no flame is detected within approximately 10 seconds, the control board shuts off the gas valve for safety.

Key Features

• OEM Suburban replacement – genuine manufacturer quality
• Dual-function design – spark ignition AND flame sensing
• 2-prong single electrode configuration
• Direct drop-in replacement – no modifications needed
• High-voltage spark generation – reliable ignition
• Flame rectification sensing – monitors burner status
• Ceramic insulator – withstands high heat
• Durable metal probe

Compatible Furnace Models

This electrode fits the following Suburban furnace models:

How the Igniter Electrode Works

Suburban NT series furnaces use Direct Spark Ignition (DSI) – there's no pilot light. Here's the ignition sequence:

1. Thermostat calls for heat – sends signal to control board
2. Blower motor starts – purges combustion chamber (15-20 seconds)
3. Spark ignition begins – control board sends high voltage to electrode
4. Gas valve opens – propane flows to burner
5. Spark ignites propane – flame established at burner
6. Flame sensing activates – electrode detects flame via rectification
7. Control board confirms flame – continues heating cycle

If the electrode fails to sense a flame within ~10 seconds, the control board shuts off the gas valve and enters lockout mode for safety. The ignition sequence will retry up to 3 times before lockout.

Signs Your Igniter Electrode Needs Replacement

• Furnace won't ignite – clicks but no flame
• Weak or no spark at electrode
• Furnace starts then shuts off after a few seconds (flame sense failure)
• Frequent lockouts requiring thermostat reset
• Cracked or damaged ceramic insulator
• Heavy carbon buildup on electrode probe
• Corroded or pitted electrode tip
• Intermittent operation – works sometimes, not others

Troubleshooting Before Replacement

Before replacing the electrode, check these common issues:

• Clean the electrode – carbon buildup can prevent proper spark/sensing. Gently clean with fine sandpaper or emery cloth.
• Check electrode gap – should be approximately 1/8" from burner
• Inspect wire connections – loose or corroded connections cause failures
• Test control board – a failing DSI board won't send proper voltage
• Verify propane supply – empty tank or closed valve mimics ignition failure

Specifications

Fits Furnace Models

Replaces Part Numbers

What's Included

• Suburban 525033 Igniter Electrode

What's NOT Included

• Gasket – Order Suburban 525011 separately

Furnace Model Decoder

NT = New Technology (DSI ignition)
12/16/20 = BTU rating (×1000)
S = Standard
SE = Standard Electronic
SQ = Standard Quiet
SEQ = Standard Electronic Quiet

Related Parts

• 071076 – Burner Access Door Gasket
• 520820 – DSI Ignition Control Board
• 521232 – Furnace Blower Motor
• 161156 – Sail Switch
• 230956 – Limit Switch

Manufacturer

Suburban Manufacturing
(A division of Airxcel, Inc.)
Dayton, TN USA

Suburban pioneered Direct Spark Ignition (DSI) systems for RV furnaces in the late 1960s and remains the leading supplier of RV heating products.