Shocking Truth Revealed: The Real Reason Why Your Furnace Transformer Keeps Blowing!

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If you experience a loud buzz, it is likely your furnace transformer. It’s not because you forgot to turn it off; rather, the device has simply overheated and exploded! Here’s why – along with what to do about it if this does happen in your home.

Why Does My Furnace Transformer Keep Blowing?

If you’ve noticed that your furnace transformer keeps blowing, consider the following:

Are you experiencing high temperatures in your abode? If yes, we recommend paying attention to how hot it is!

If so, take action. Open up your windows and fan systems at your residence – if heating needs to be increased to compensate for any resulting temperature drop; don’t despair; simply find ways to make yourself more comfortable with minimal exertion on your end.

Tutorial: How to Replace a Furnace Transformer?

If your furnace transformer has gone out, then it’s time to acquire a replacement. To save yourself some hassle and expense incurred in purchasing a new unit, you can simply unbolt the old one from where it is mounted and swap it out for a new one!

If you lack the necessary tools or experience required for repairing your own home equipment, don’t fret! This article will provide you with step-by-step instructions for removing and replacing your defective transformer.

  •  Unplug the electrical components that stay connected to the existing furnace transformer.
  • Then remove any screws securing it to its mounting bracket; next, unplug its cables while leaving the terminal connectors intact.

Step 1: Turn off the Power to Your Furnace

Your furnace transformer is a device that connects the power source to your furnace. This saves you time and money by providing energy to your home when needed – typically when it’s cold outside or during periods of power outages.

Therefore, it’s essential that the unit be shut off before beginning any repairs. First, turn off the power at your fuse box; then locate your furnace’s circuit breaker and flip it to ‘off’.

Step 2: Remove the Hose from the Cold Water Line

Gazing upon the hose that connects to your hot water tank, unclasp it from its hook and slide it out of the way.

To discover whether or not your furnace is in need of an overhaul, you’ll need to ascertain how much H2O pressure the system is generating as well as check its temperature. To do so, simply observe the dials on your thermostat; if they don’t match up with what’s being displayed by the gauge beside them – indicating temperatures within range – then it could be time for some upgrades! If there’s no change when compared to earlier readings then this could indicate a leak in the HVAC unit resulting in a drop in power output.

Step 3: Remove the Nuts That Hold the Electrical Wire To The Hose

Once you have unscrewed each bolt, take out the electrical wiring with pliers or a wrench.

If your transformer is being replaced at this juncture, it could be a different size than the one that was installed initially. If this situation arises, don’t fret – just swap it out for another accordingly.

Once you’ve removed all of the mounting hardware from around the coil and wires, give it a thorough inspection to ensure there are no loose bits or pieces along its length.

Step 4: Loosen and Take Off The Screws That Hold The Furnace Voltage Terminal Cover Plate

With the terminal cover plate loosened, now is an ideal time for you to remove it! Be sure not to lose any screws; they’re essential if you intend to put the furnace back together in the future.

Determine which screw came out first then tighten it up while taking note of its location so as to prevent future issues such as forgetting where one goes or trying to install components without knowing how they were previously secured.

Step 5: Remove The Voltage Terminal Cover Plate From The Bottom Of The Transformer

Now that the terminal cover plate has been removed from the bottom of the device, it’s time to proceed with the next step – inserting a probe into the box and locating its terminals.

With the ampacity circuit completed and all connections made, you should now find yourself gazing upon a magnificently familiar sight – six wires leading away from their respective terminals!

Connect one end of an ohm-scale resistor to one of these wires; then connect another end to the ground. To ensure precision in your calculations, choose a value between five and twenty-five ohms.

Step 6: Remove The Old

If you have been diligent throughout this process, then your transformer should now be in its rightful place in the furnace.

Ensure that it is well secured in its socket with screws or rivets and that its terminals are properly connected. Turn on the power switch on the receptacle box to finalize these tasks and ensure maximum efficiency!

Damaged or Dirty Furnace Transformer From The Bottom of Your Furnace

If your transformer is situated at the bottom of your furnace, then its unanticipated demise might be due to an accumulation of gunk and grime accumulating on the unit.

If this happens, chances are it could take some time for the clogged-up area to be cleaned up. While this can occasionally be done manually by hand – most furnaces today come equipped with electric access panels for expedited cleanup efforts!


Despite the numerous methods to rectify this issue, it is imperative that you contact a pro for assistance in resolving it. If your furnace is still under warranty or if you possess an extended warranty plan then don’t hesitate to contact us – we’ll be glad to assist!