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Understanding Why Your Furnace’s High Limit Switch Keeps Tripping

Is your furnace acting up on you again? We’ve all been there – one day it’s keeping you nice and cozy, the next it’s leaving you out in the cold. It could be because your furnace’s high limit switch keeps tripping. But don’t let it ruin your day just yet. Let’s figure out what’s going on with that stubborn thing.

The job of a high limit switch is to make sure your furnace doesn’t overheat and cause any safety issues. But when that switch is constantly pulling the fire alarm and cutting your heat, that’s just plain frustrating (not to mention chilly).

So for fellow Hoosiers and Ohioans out there, we’re going to break down the most common culprits behind those high limit switch tantrums. We’ll walk through whether it’s something you can troubleshoot yourself or if you need to call in the pros before your furnace goes completely haywire. Nobody wants to be left out in the cold this winter!

Furnace Maintenance

What is a Furnace High Limit Switch?

Okay, let’s talk about your furnace’s high limit switch that’s been causing you headaches.

Basically, it has one job – making sure your heating system doesn’t get so hot that it becomes a safety issue. It keeps an eye on the temperature inside that heat exchanger area. If things start getting too toasty in there, past the point of what’s considered safe, the high limit switch steps in and shuts the whole furnace down before any real damage happens.

An overheated furnace is seriously bad news. It could lead to potential cracks in that heat exchanger, carbon monoxide leaking out, or even fires if it gets really out of control. Yikes! 

The high limit switch is what stands between you and a whole bunch of expensive repairs or dangerous situations. Sure, it’s a pain when it keeps tripping and cutting your heat. But in the long run, it’s doing you a favor and keeping your home and family safe.

For something so small, it plays a huge role in how your furnace runs. Instead of just getting frustrated with it, let’s figure out why yours keeps getting all worked up.

Common Reasons the High Limit Switch Trips

Okay, now that we’re all on the same page about what this high limit switch actually does, let’s dig into why it keeps throwing a fit. There are quite a few potential culprits:

Restricted Airflow

For starters, restricted airflow is a major no-no for furnaces. If your air filters are clogged up with dust and grime, vents are blocked by furniture or other objects, or you have too many registers closed off in unused rooms, it makes it really hard for air to circulate properly through the system.

That lack of airflow means the furnace has to work overtime trying to push out heat, driving up those internal temperatures way too high. Hello, tripped high limit switch!

Dirty or Clogged Heat Exchanger

Another culprit is if you’ve got a dirty or clogged up heat exchanger. Over years of use, that core component can accumulate all sorts of built-up gunk, soot, and debris. All that crud acts like insulation, trapping heat inside instead of letting it dissipate out.

Keep running your system like that for too long and you’re just asking for an overheating situation that’ll have your high limit sensor losing its cool and shutting everything down.

Oversized Furnace

Sometimes the root issue is that your furnace is simply too big and powerful for the square footage it’s trying to heat. 

These oversized units tend to cycle on and off rapidly in an attempt to maintain temperature. But they don’t give the blower fan enough run time to evenly distribute that heat throughout the home. So you get hot spots and cold spots that make the high limit think there’s a raging fire!

Malfunctioning Blower Motor

Speaking of blowers, if yours has seen better days and isn’t running as effectively as it used to, that can starve parts of the furnace of proper airflow too. The heat exchanger areas may get too little air moving across them, leading to overheating.

The same is true for ductwork that’s undersized or installed poorly – you’re just not getting sufficient airflow from another angle.

Faulty High Limit Switch

And you know, in some cases, the high limit switch itself could just be going haywire or becoming overly sensitive! These things can get a little glitchy or defective with age, basically crying wolf about overheating when the temperature rise is actually within normal bounds.

The bottom line is, something’s gotta be throwing your furnace’s temperatures out of whack for that high limit switch to keep throwing down the red card. Whatever it is, we’ve got to sniff out the real culprit behind those constant trips!

Risks of Ignoring a Tripping High Limit Switch

We’ve all been tempted to just ignore the high limit switch when it keeps tripping. Just reset it and keep it pushing, right? But ignoring those warning signs can seriously come back to bite you. We’re talking major risks to your furnace system, your wallet, and even your safety.

System Damage

Every time that high limit trips due to overheating conditions, it puts extra strain and stress on your furnace’s internal components. The heat exchanger, blower motor, control board – they’re all being taxed beyond their limits. Keep running things at those unsafe temperatures and you’re just accelerating wear and tear.

What might have been a quick fix could turn into a full system breakdown way sooner than expected. Replacing an entire furnace is one expensive repair bill!

Increased Energy Costs

On top of the physical toll, frequently tripping the high limit makes your furnace an energy hog too. All that rapid cycling on and off as it overheats and shuts down? It’s just incredibly inefficient and wasteful operation. 

Those constant restarts use way more fuel than a system running smoothly. So while you’re ignoring the root issue, your utility bills are just silently climbing through the roof. Here are a few extra tips on how to improve the energy efficiency of your furnace.

Safety Hazards

But most importantly, continuing to run an overheating furnace when the high limit is tripping can create some serious safety risks. We’re talking potentially cracked heat exchangers that could start leaking carbon monoxide into your home’s air supply. Or, worse, an out-of-control fire sparked from those extreme temperatures!

So when that high limit switch starts acting up, you need to take it seriously. A few simple resets might be okay as a temporary band-aid. But if it keeps happening, get to the root cause ASAP before you’re stuck dealing with an expensive, hazardous mess. That annoying little switch may be inconvenient, but it’s trying to protect you!

Troubleshooting and Resolving the Issue

Okay, we’ve established that ignoring your high limit switch when it’s tripping is a terrible idea. We’re talking expensive repairs, crazy energy bills, or even safety hazards like carbon monoxide poisoning or fires. Not something to mess around with! Time to roll up our sleeves and get to the bottom of this issue.

Step 1: Check Those Air Filters

One of the most common reasons for high limit issues? Clogged up air filters. Yes, it’s an easy one to overlook. But those things can get disgustingly full of dust, pet hair, you name it – completely blocking airflow if you let it go too long. And restricted airflow leads to overheating real quick.

Do yourself a favor and make a habit of checking the filters monthly and replacing them when they’re dirty.

Step 2: Give Vents and Registers a Once-Over

While you’re thinking about airflow, take a quick peek at all the vents, registers, and returns around your home too. Shoved up against a wall by furniture? Blocked by your kid’s pile of toys? Covered in pet hair and fuzz? Any of those obstructions can be the culprit. Clear away any blockages and give those vents a good vacuum if they’re dusty.

Step 3: Watch Your Furnace in Action

Spend some time just observing how your furnace behaves when it’s running. Cycling on and off like a jackhammer every few minutes? Noticing major hot or cold spots in certain rooms? Temperatures fluctuating wildly? Patterns like these can clue you in to issues like an oversized unit, airflow problems, or any of the other culprits.

Step 4: Do a Basic Visual Check (If You’re Comfortable)

Feel free to do a quick visual once-over of the accessible furnace components too, but don’t go too wild. Things like checking for debris buildup around the blower fan or visible cracks in the heat exchanger. Just don’t touch or disassemble anything you’re not qualified to work on – safety first!

Step 5: Call in the Pros

Tried all those basic steps and the high limit switch still tripping? Or suspect there’s a faulty switch, blower issue or other component causing overheating? That’s the signal to wave the white flag and call in professional HVAC backup. Certified techs have the proper tools and know-how to do a deep inspection, clean out built-up gunk, and repair or replace any problematic parts. Don’t risk messing with stuff beyond your abilities!

The name of the game is taking it step-by-step to solve the mystery. Try the easy DIY troubleshooting first to rule out simple fixes. But know when to hand it off to the experts before you get in over your head. Resolving high limit drama is a process, but worth it to get your heating system running smoothly and safely again.

When to Replace a Furnace High Limit Switch

Okay, so you’ve been through all the troubleshooting steps – replacing filters, clearing vents, monitoring weird behavior. But that pesky high limit switch is still tripping like it’s got a mind of its own. At this point, the switch itself could be the real culprit behind all the drama.

There are a few telltale signs that it may be time to replace that high limit switch:

  • It’s tripping constantly, even when airflow seems fine and other components look good. If you’ve ruled out all the usual overheating suspects, that points to a faulty switch.
  • The furnace keeps overheating quickly, even after you reset the switch. Like it can’t even run for 5 minutes before hitting the limit.
  • You’ve got an older furnace and the switch is original/has been through the ringer for years. These things can get glitchy over time.
  • The switch is visibly damaged – cracked casing, frayed wires, scorch marks, etc. A sign it’s taken one too many heat beatings.

If any of those scenarios sound familiar, the high limit may simply be too old, too sensitive, or too busted to keep properly regulating furnace temperatures anymore.

Of course, the only way to know for sure if replacement is needed is to have a professional HVAC tech take a look. They’ve got all the diagnostic tools and experience to thoroughly test the switch and determine if it’s still operating within proper specifications. No more guesswork on your part!

A technician can also take a look at the entire furnace system as a whole. Maybe the switch is fine, but there are other components on their way out that are causing the constant overheating issues. They’ll be able to make an informed call on whether replacement is the right fix, or if you need to start budgeting for a whole new furnace installation down the line.

If you’ve tried everything you can to resolve those high limit problems and it still won’t cooperate, don’t be afraid to call in an expert. Replacing a faulty switch is a whole lot cheaper than completely neglecting the issue until your furnace becomes a safety hazard or expensive paperweight!

Keeping Your Furnace Out of the Doghouse with Bassett

When your furnace’s high-limit switch just won’t stop throwing a fit, don’t let it leave you out in the cold! Trust Bassett Services – a better breed of service that’s doggedly determined to get to the bottom of any heating issue. Whether you need basic DIY troubleshooting guidance or a professional hand, our home hounds have your back across Indiana and Ohio.

Our expert heating techs are equipped to sniff out even the most stubborn high limit switch problems, repairing or replacing faulty components with top-notch workmanship. But Bassett’s services don’t stop there – we’re your home’s best friend for any furnace repair, installation, or maintenance needs. No tricks, just treats for your heating system!

So next time that high limit has you howling, sound the hound and dial (317) 360-0054. Bassett will be by your side with tail-wagging service to get your furnace back in top-dog shape.

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