How To Tell If Your Furnace is Broken

The avatar of Scott Kirschner

Scott Kirschner

Oct 26

Learning how to tell if your furnace is broken will help you move one step closer to figuring out what’s wrong with your heating system. In this post, we provide you with a list of signs that your furnace is broken and then we give you a recommendation for how to find a heater repair service in your local area.

Continue reading to learn how to tell if your furnace is broken and needs repair. If none of these apply to your situation, you still should go ahead and contact an HVAC pro to diagnose your specific heating problem.

How to Tell If Your Furnace is Broken: 7 Signs

The below signs are the most common ways to tell if your furnace is broken.

Thermostat Is Not Working

A non-working thermostat is likely to be one of the earliest problems you’ll encounter if your furnace is broken. For instance, if you raise the temperature on the thermostat and there is no change in physical air temperature, your furnace is broken. In this case, you should hire an HVAC contractor to get it fixed.

Bill is Unexpectedly High

If your bill balance is unusually high and there isn’t anything in particular that you remember happening to create a spike in your energy costs, this could be a sign that your furnace is broken. If your furnace isn’t working properly, it can run unnecessarily and consume too much energy.

If you haven’t already, check the details of your most recent energy bills and pinpoint the date of any drastic changes, and go from there.

Airflow is Weak

If the airflow in your house is weak, this could be another sign that your furnace is broken. Your vents should be noticeably blowing warm air out in a flow that can actually heat up your home quickly.

This could be an issue with the fans or belts and motors. Whatever the case may be, you need to hire an HVAC pro to make sure the issue is properly diagnosed.

Cold Air Comes Out

If cold air is coming out of your vents while your thermostat is set to increase the temperature or keep your house warm, this spells trouble. This might be an issue with your pilot light or thermocouple.

A local HVAC professional will be able to best assess the situation.

Furnace Repeatedly Cycles

If your furnace continuously kicks on and off and it doesn’t seem like much else is happening, this is another way to tell that your furnace is broken. Thermostat problems and dirty filters are some of the possible issues here.

To be 100% certain what the problem is, you need to contact an HVAC contractor. 

You Smell Gas

If you smell gas, you could have a gas leak. This can be pretty dangerous, so make sure you shut off your furnace and hire an HVAC pro immediately to fix it.

In the meantime, turn off the gas supply valve and avoid turning on any lights or lighting matches.

There’s Water Around Your Furnace

If you spot water pooling around your furnace, this means you have a water leak. It could also potentially be a gas leak, but it’s likely just water if you don’t smell gas.

Often, water leaks around a furnace are caused by a clogged line. Don’t tinker with it yourself, because you’ll need to hire an HVAC professional that has plumbing experience as well.

Heating Experts To Fix Your Broken Furnace

If you need to find a heating expert in your local area to repair your furnace, use

Service is the best place to find a reliable contractor. We only list vetted HVAC pros, and we provide unparalleled support to you as a homeowner.

With conveniences such as online payments, dispute resolution assistance and a handy mobile app for chatting with your contractor, look no further than


The avatar of Scott Kirschner

Scott Kirschner

Oct 26

Being the Marketing Director at Scott works on automation for e-commerce as well as creative design. In his free time Scott plays in several bands around Detroit, MI. He enjoys backpacking through the outdoors and traveling across the world.