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Boiler Basics

Imagine turning on your shower and waiting for it to heat up in the winter only for the water to stay cold. Or maybe the water that comes out of your faucet is always cold, even if you are using the hot side. These would be signs that something is wrong with your boiler.

When it comes to boilers, not many people are educated about how they work. It is not until you need a boiler repair in Chicago that you are interested in learning more about how they operate. At Deljo Heating, Cooling & Plumbing, we provide the Chicagoland area with heating and cooling solutions for even the most unexpected situations! Before winter hits in full effect, here is some more information about how boilers work and the different kinds that may be in your home.

What is a Boiler?

Don’t take your boiler for granted! This is an appliance that is responsible for heating your home’s water for reasons including cooking, showering, and central heating. There are different kinds of energy that are used to run boilers, including wood, coal, oil, natural gas, and resistance heating elements.

Types of Boilers

Generally speaking, there are three different types of boilers that your house or apartment may utilize. The three types include a combination boiler, a system boiler, and a standard boiler. Here are some of the differences between the three:

Combination Boilers

This type of boiler combines high-efficiency water heaters with a central heating boiler, which is why they are referred to as combination boilers. The water in the main water line is heated directly, which eliminates the need for a cylinder that stores water. The advantages of this type of boiler include cost-effectiveness and energy efficiency. Your overall energy bills are likely low with this type of boiler.

System boilers

System boilers are composed of a cylinder that stores hot water, however, the majority of both heating and hot water systems are built into the actual boiler, making it easy to install. Plus, system boilers are compatible with solar water heating systems!

Regular Boilers

Regular boilers also referred to as traditional boilers or heat-only boilers, contain a cylinder to store hot water and require two tanks. One tank is for storing cold water and the other is used for maintaining water levels for the central heating system.

How Long Do Boilers Last?

We know that you want to get the most out of your investment. Our heating contractor in Chicago tells our customers that the more you put into taking care of your boiler, the longer they will last. On average, boilers last 10-15 years with the right care.

If you have questions about taking care of your boiler or you need a boiler repair in Chicago, contact Deljo Heating, Cooling & Plumbing today!

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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