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Gas Furnace Problems

As soon as the cold weather arrives, many people call Deljo Heating, Cooling & Plumbing for furnace repair in the Chicago Loop and other areas of Chicagoland. Whether it’s a residence or a commercial setting, the basic causes of gas furnace problems tend to be similar, and by knowing what these are you can become proactive and prevent many of them from occurring.

Lack of Maintenance

Regular, professional maintenance is absolutely essential to keep your system working properly. Lack of professional maintenance can lead to a poorly performing unit, unexpected breakdowns and increased energy costs.

Dirty or Clogged Filters

Monthly replacement of the filter in your furnace is one of the easiest and most important things you can do to increase the efficiency and extend the life of your furnace. A dirty filter restricts the air flow through the system and makes your furnace work harder to circulate warm air.

Mechanical Wear and Tear

Your furnace contains many mechanical parts essential to the operation of the system. Wear and tear on these parts can lead to numerous problems, but a heating specialist performing regular maintenance can prevent many of these problems from occurring.

Pilot or Ignition Control Problems

Today’s gas furnaces typically contain one of two possible ignition systems:

  • Hot surface ignition
  • Intermittent pilot

The hot surface system uses an electrically controlled resistance heating element (like the filament in a light bulb) to ignite the gas burner. The intermittent pilot system is also electronically controlled but uses a high voltage electrical spark to ignite the pilot and main burner. If the pilot isn’t working, check to see if an electrical surge has tripped a breaker cutting off power to the unit. If not, unless you’re highly skilled, it’s probably best to call for professional help.

Thermostat Malfunctions

The thermostat determines when and how much heat is produced to keep you warm, and problems with the thermostat can lead to intermittent heat or no heat at all.

It’s essential to remember that furnaces and thermostats are not mix and match. Using the wrong thermostat with a furnace can cause serious problems, so with this problem it’s best to call in the professionals at Deljo.

If you need furnace repair in the Chicago Loop and surrounding areas, call Deljo Heating, Cooling & Plumbing at 773-829-4295. The specialists at Deljo are the best in the business and are available 24/7, 365 days a year to come to your assistance.

Client Testimonials

Read the opinions of our satisfied customers.

5 stars

This was my first time as a Deljo customer, and I was very pleased. My technician, Giovanni, was very thorough and diligent. He serviced my furnace and identified a faulty sensor that was causing the unit to shut itself down. Deljo ordered the part, and Giovanni replaced it a few days later. Overall, the team at Deljo was great. The dispatcher kept me informed about Giovanni’s arrival time, and the supervisor assisted Giovanni when he was diagnosing the problem with the furnace. I highly recommend Deljo.

Paul D. 10/15/2026

5 stars

I’ve used Deljo for over 10 years now and they always do a good job. Izzy was the technician for this visit and he did an excellent job with my winter maintenance on my multiple units in the household. He also addressed an issue while cleaning the furnace blower wheel. His communication was clear and concise with what he planned to do to address the issue quickly. He was confident and I had 0 concerns or questions. Great job Izzy!

Jeff S. 10/14/2026

5 stars

Paul was great! Arrived on time and completed maintenance on my humidifier, tankless water heater, and two furnaces. All work was performed under my Gold Star maintenance program, so all maintenance charges were covered. Paul did provide a few proposals for additional services on furnace & tankless water heater, but those were emailed to me for further consideration. Paul was friendly, knowledgeable, and answered all my questions.

Jack N. 10/12/2026

5 stars

Gabe did an excellent job with our annual service visit. He arrived in the early part of our service window, was friendly and knowledgeable, and got the work done in a very reasonable amount of time. I have great confidence in Deljo, and am a long-time customer.

Ruth C. 10/9/2026

5 stars

I’ve been using Deljo for 20 years for HVAC but now venture into enlisting their plumbing services. Bashar was very courteous, efficient & informative, and I’d definitely request him again for the next plumbing job. Great experience!

Christopher R. 10/2/2026

5 stars

Working with Deljo is always a good experience, and today’s appointment with Izzy was no different. He was able to come early which actually worked better with our schedules, but called me ahead of time to make sure that was okay. He was friendly and knowledgeable when he explained the work he had done during his visit and our options for fixes. He was also able to schedule a quote appointment for us while he was still here. We would highly recommend working with Izzy and the Deljo team!

Lauren H.  9/25/2026

5 stars

Drew performed the seasonal maintenance on my AC. It needed some repairs and updates and he was able to fix everything at the same appointment. He also noticed issues with the hot water heater and we were able to get ahead of that, as well.

Emily W. 9/11/2026

5 stars

I would leave six out of five stars if I could! My technician Jorge went above and beyond on his service. There was buildup in the rental property’s toilet from the previous tenant. One maintenance person did a surface level job of cleaning but did not fully remove the obstruction. Jorge went above and beyond and came to a solution and even explained the perpetual problems older toilet models can cause. Moving forward with this insight, I can perform my own upkeep the previous tenant did not. Thank you kindly!

Kayla K.  9/15/2026

5 stars

We just had our new boiler installed by Jonathan and Carlos. First rate work! They arrived on time, removed the old boiler, installed the new unit, and explained the features. Both guys were pleasant. Bring on the cold this winter! We are ready thanks to the team from Deljo.

Edward B.  6/26/2026

5 stars

Deljo’s heating and cooling team was awesome to work with. As a first-time homeowner, I really appreciated how clearly they explained everything and answered all my questions. From the quote to the install and follow-up, the service was top-notch. Highly recommend!

Lindsey A. Chicago, IL

5 stars

Matt did an amazing job. He serviced our home and our rental property. He gave us options to help our systems run more efficiently. He also told us about Deljo’s new plumbing inspection which was very affordable. He is great!

Jordan R. Chicago, IL

5 stars

We had a problem with our Humidifier and called Deljo. Jesus came out to help and was amazing. He was extremely knowledgeable, detail oriented, and super courteous. Amazing customer experience!

Jeff C. Chicago, IL

5 stars

Jordan and Jesus were extremely helpful and knowledgeable! We would 100% work with them and have them back. They were both very professional and efficiently fixed our heating system.

Emily L. Chicago, IL

5 stars

Shout out to Ernesto for coming out and servicing our furnace and air con. Deljo provides a great service and glad to trust them with our HVAC for our small business.

Lauren H. Chicago, IL

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