Why Is My Furnace Raising My Gas Bill?

Worried about high gas prices? You’re not alone. Many homeowners notice rising heating costs during the winter, but sometimes the spike is a lot higher than what weather conditions can explain. But you have to consider everything that’s in play. Your gas furnace, home insulation, energy usage, and even the condition of other appliances can all contribute to high gas bills. In more serious cases, a hidden gas leak or natural gas leak can drive natural gas usage, and obviously that’s not something you should ignore. Understanding the different causes can help you pinpoint the real problem—and get you back to savings!

Why Is My Gas Bill Suddenly So High?

A sudden jump in your heating costs can happen for a variety of reasons. We want to keep warm in winter. So extreme weather conditions during the cold months can cause your HVAC system to burn through more natural gas to maintain the temperature you want inside. Then again, if your home also has outdated appliances, like an older water heater or clothes dryer, then you might be noticing that your energy usage is climbing too. You likely have lots of things running in your home. Each one has a cost that can fluctuate.

 

Why Is My Furnace Using More Gas?

Running the heat in winter is one thing, but there are other reasons why your furnace might be using more gas. For example, your gas furnace may be using more fuel if it’s cycling on too frequently or blowing cold air instead of creating warm air.

Poor airflow, dirty filters, and failing parts can all increase natural gas usage because the system must run longer to meet demand. Even something simple like an older filter slowing airflow, or making lots of small adjustments on your thermostat throughout the day can force the furnace to heat inefficiently.

What Raises the Gas Bill the Most?

The primary things to consider for why a gas bill is so high include inefficient furnaces, poor insulation, high electric bills from other appliances, and increases in the cost of gas itself. Long heating cycles, leaky ducts, and aging systems all require more natural gas to deliver the same amount of warm air. Outdated water heaters and the extra strain that we put on our systems during cold months can also make high bills even worse.

How Can Poor Home Insulation Drive Up Gas Bills?

Poor insulation is one of the leading hidden causes of rising heating costs. Without proper weather stripping on your outside doors or well-insulated walls, your home loses heat quickly. The same goes for not having closed gaps around windows. These mistakes force your HVAC system to run longer and burn more natural gas just to maintain a comfortable temperature.

Where Does Heat Escape Most in Your Home?

Heat loss most often occurs around windows, attic hatches, doors, and uninsulated walls. If you’re noticing cold air coming through, take a closer look at what’s going on! Cracks or gaps allow warm air to escape and cold air to enter, raising your energy usage. Even a well-performing gas furnace can’t offset constant heat loss—meaning your home becomes more expensive to heat throughout the billing period. Some quick home improvements for insulation can help lower what you’re spending.

What Furnace Problems Cause Excessive Gas Usage?

A poorly functioning gas furnace is a major reason your gas bill increases. This is one of the reasons why routine maintenance is key. You want to make sure your system isn’t running on worn parts. Plus, your air filter needs to be relatively clean. Airflow restrictions cause the furnace to run longer, which just ends up wasting gas and raising your electricity consumption.

How Does a Malfunctioning Thermostat Increase Gas Bills?

A failing or outdated thermostat can cause short cycling, constant running, or inaccurate temperature readings. This pushes your HVAC system to use more natural gas while making your home feel too warm or still too cold. Maybe it’s time for a newer model! Upgrading to a smart thermostat can help you fine-tune your desired temperature, reduce waste, and improve overall energy savings.

Can Blocked Vents and Dirty Filters Make Your Furnace Work Harder?

Absolutely. Blocked vents, clogged filters, or obstructed ductwork force the furnace to run longer to deliver warm air. Restricted airflow can also cause overheating. This is a problem because it triggers the furnace to shut down and restart repeatedly. That means you’ll be wasting gas and seeing increasing electric bills.

How to Tell If a Furnace Is Leaking Gas

A natural gas leak or gas leak is a serious hazard—and it also drives your natural gas usage and heating costs through the roof. Signs include a sulfur smell (“rotten eggs”) or hissing near the furnace. It’s important to check out your system if you see a sudden spike in your gas bill. If you notice these signs, leave the home immediately and call your gas utility. Never ignore a gas leak. You’ll not only be paying more, you’ll be risking your safety too.

When Should You Replace a Furnace That's Raising Your Gas Bill?

If your furnace is over 15–20 years old and requires frequent repairs, then you might be ready to invest in a new system. Fortunately, this doesn’t have to break the bank! When you know where to shop, you can collect some big savings. That’s what we do here at Surplus City. We source directly from the manufacturers to keep our costs low. Then we pass those discounts on to you!

Old HVAC equipment is usually less efficient, which means you might notice continuously higher and higher bills. When that happens, a replacement may be the most efficient and cost-effective option. Newer systems use far less fuel and electricity.

What Is AFUE and Why Does It Matter for Gas Bills?

AFUE (Annual Fuel Utilization Efficiency) shows how efficiently your furnace converts gas into warm air. Older units often have AFUE ratings between 60–70%, meaning 30–40% of fuel is wasted. Modern furnaces can reach 95% or more. This is great because it will dramatically lower your heating costs. High-AFUE units, especially when paired with net metering or smart energy practices like better insulation, help homeowners save money and improve long-term energy savings.