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Common HVAC Myths

Your HVAC system works tirelessly in the background to keep your home warm in the winter and cool in the summer. Unfortunately, there’re a number of myths commonly associated with HVAC systems, and for you to enjoy the best in heating and cooling in Chicago, we’d like to explore a few of those.

Myth 1: Turning my thermostat all the way up or down will make my home heat or cool faster.

Turning the thermostat way up or down, known as oversteering, doesn’t speed up heating or cooling. Your HVAC system works at one speed, no matter the setting, high or low. It’s best to set the thermostat at the temperature you desire and leave it there. Otherwise, if you forget to adjust it later, your system works overtime and wastes a lot of energy.

Myth 2: The HVAC technician replaces the filters during his service visit, so I don’t need to replace filters.

While our technicians will gladly replace your filters during a service call, it’s important for you to change your filters regularly. A clogged filter makes your HVAC system work harder to circulate air. Replacement varies from household to household, depending on things like household size and the number of pets, but you should check your filters every 30 days and replace as necessary.

Myth 3: I should cover my HVAC’s outdoor unit during winter.

Covering the unit seals up moisture and speeds up corrosion. Instead, if a heavy snowfall is expected, cover the fan temporarily with something like a piece of plywood.

Myth 4: During the summer, I should set my thermostat to a higher temperature while I’m away.

Not a good idea. Once you’re home and turn the thermostat down, it’s hard for your HVAC system to catch up. You’ve actually created a lot of load for the system to overcome before it starts cooling again.

Myth 5: I only need to call an HVAC specialist when something breaks.

Like any complicated machinery, your HVAC unit needs periodic maintenance to run efficiently. The dollars you spend on regular maintenance will be easily made up by lowering energy bills and extending the life of your system. And the warranties of many manufacturers require regular maintenance.

For the very best maintenance for heating and cooling in Chicago, call Deljo Heating, Cooling & Plumbing at 773-829-4295 and let us provide the support you can trust and count on.

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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