Oil Furnace Ignition Repair and Transformer Replacement

Low voltage transformers can be found on the zone valves or on the thermostat of your furnace. When the transformer stops working properly, it can lead to problems with your furnace such as the igniter failing to start and the furnace overheating. A furnace should never be allowed to overheat as it will catch fire and could cause severe damage to your property while putting your lives at risk.

Diagnosing The Problem

Modern furnaces have a warning system built in, a flashing light will tell you the furnace is ‘locked out.’ You will need to shut the power down before removing the front of the furnace. Next is to locate the igniter itself. If the igniter clicks, it is a ‘spark igniter’ and will usually be located within a gas pilot tube next to the gas control valve. If it looks similar to a light bulb and glows, it is a hot surface igniter If you notice cracks in the hot surface igniter, it needs to be replaced without delay.

What Causes The Spark Igniter To Stop Working?

Cracks in the ceramic base and build up of dirt, dust, and oil are the common factors for spark igniter failure. While the latter is not so serious and can be rectified through cleaning, a cracked spark igniter requires replacement.

What Causes The Hot Surface Igniter To Stop Working?

The hot surface igniter or ‘HSI’ can fail due to contact with oil, the electric current in your property being too high or simply because it has reached its usage cycle. The scenario is pretty much the same as before. A clean up should do the trick but cracks mean it’s time to replace the igniter

What Is An Ignition Transformer And What Does It Do?

A perhaps less common problem is ignition transformer failure. The transformer converts electric voltage to create the impetus for the igniter to spark. As with igniters, the transformer can be damaged by moisture and leaked oil. It is standard practice for furnace technicians to carry out an output voltage test using a voltmeter. We strongly advise against untrained attempts at diagnosing and replacing the transformer. Without the proper knowledge and experience of performing such tasks, you run the risk of electrocution. There may be issues with the wiring connected to the transformer and the burner which are undetectable to unqualified non-professional and should not be tampered with for the same reasons previously stated.


For a few bucks, you will be protecting your heater/boiler and safeguarding your property from catastrophic and devastating consequences to your property. If your igniter won’t work after repeated tries, give us a call and leave this complicated and hazardous work to a licensed and fully trained professional furnace technician. We can be there within hours, we serve all of Long Island and the surrounding areas so there’s no cause for panic. Before the day is out, we’ll make sure you are safe and warm again.