Blog

Understanding the Furnace Installation Process From Start to Finish

Installing a new furnace in a home is a much more complicated process than most people realize. Removing an older furnace and replacing it can be time-consuming, but it can usually be completed in one day. However, it is always something that has to be done by a certified technician. You can’t just plug in a furnace, hook up the gas, and have it ready to go. There are a huge number of steps and tests that need to be done to ensure it operates safely and heats effectively. This guide will show you all of the various steps involved in replacing or installing a furnace so that you know what to expect during the process.

Load Calculation

Before installing a new furnace in a home, technicians will need to perform what’s known as a Manual J load calculation. A load calculation is essential as it enables them to accurately determine what size the furnace needs to be to heat the home effectively and operate as energy efficiently as possible. When performing the load calculation, technicians will take into account a wide variety of different factors including the home’s square footage and the climate zone.

They’ll also need to measure the level of insulation in the home and check how well-sealed it is or how many air leaks the structure has. These factors can contribute to heat loss. How many windows and exterior doors the home has, their sizes, and which direction they face are also important for factoring in both heat loss and heat gain. A load calculation always needs to be performed to ensure the new furnace isn’t undersized or oversized and works as effectively as possible.

Safety Check

Before removing the old furnace, our technicians will first perform a safety check to eliminate any potential hazards. This basically involves making sure the circuit breaker is shut off and the HVAC system doesn’t have power, shutting off the gas lines and inspecting for leaks, etc. Furnace installation is almost always a two-person task, and the technicians will always perform safety checks throughout the process.

Disconnecting and Removing the Old Furnace

Before the old furnace can be removed, our technicians will need to disconnect everything from it. This includes the electrical wiring, gas lines, exhaust vents, ductwork, etc. They will also lay down a protective covering to prevent damaging the floor. They will then remove the old furnace and take it outside of the house and also remove the blower if it is being replaced as well.

Preparing the Area

Once everything has been removed, the technicians will then prepare the area for the new furnace. This involves cleaning underneath where the old unit sat and cleaning out the ducts that connect to the furnace. It is also often necessary to make some alterations as the new furnace may be a different dimension or set up differently. In this case, our technicians may need to alter the existing ductwork or change where the furnace filter is located. They may even need to make slight changes to the nearby walls to ensure the furnace has sufficient clearance. This is important both for preventing fire hazards and ensuring it works effectively.

Installing and Connecting the New Furnace

Our team will then haul the new furnace inside and set it in place. Some of the alterations we mentioned can only be done when the furnace is in place. This means they may need to do some things as they go, such as building a new sheet metal supply plenum to ensure the unit has proper airflow. Before setting the furnace, it is important to lay down a rubber pad or something to isolate it so that it isn’t sitting directly on the floor. If the furnace isn’t isolated, the metal will draw moisture out of the floor and quickly start to rust.

Once the furnace is set, our technicians may need to adjust it or add some type of shims so that it is perfectly plumb and level. The inside of the furnace then needs to be completely sealed using a special caulk to make sure it’s able to withstand the pressure that occurs when the unit runs. They’ll then reconnect the ductwork and seal the connections to prevent air leaks before finally reconnecting the electrical wires and gas line. In some cases, it will be necessary to run additional wiring or repair or replace the existing wires. If the gas line is rusted or in poor condition, they will also replace it and run a new line before setting the furnace.

Commissioning, Calibrating, and Testing the Heating System

Commissioning is an HVAC term you’re probably not familiar with, but it is an important process that must be performed when installing a new furnace or any type of heating or cooling unit. Commissioning a furnace essentially means starting up the furnace and making sure it is working according to the manufacturer’s specifications and within the specific parameters of the home’s heating system. The process is quite complicated and will usually take a technician 45 minutes to an hour and sometimes even longer. There are at least several dozen different things that need to be tested and checked.

The reason that commissioning a new furnace is so essential is that every HVAC system is different, which means that no furnace is ready to operate properly out of the box. The size of the home and the distance of all of the rooms from the furnace and blower need to be accounted for when setting up and calibrating the system. In addition, the shape and size of the duct system is just one of many other important factors.

When commissioning and calibrating a new furnace, our technicians will turn the heating system on and then use a digital gauge to perform a variety of different tests. They’ll test the gas pressure coming into the furnace and the temperature of the air coming out of the furnace in each different heating phase. They’ll also measure how many cubic feet of air the blower is moving through the ductwork and make sure the blower is operating at the right amperage. If a new blower was installed, it will need to be tuned so that it operates at the proper speed and moves the correct volume of air. They’ll also need to measure the static pressure to make sure there aren’t any issues leading to increased airflow resistance. This would limit the effectiveness of the heating system.

Performing these and all of the other necessary tests allows the technicians to calibrate the furnace and the entire heating system so that it works as effectively as possible. Calibrating also helps everything to work more efficiently to prevent the system from using too much energy and also to decrease wear and tear on all of the components. If a heating system isn’t properly calibrated, it will likely experience more issues, need more frequent repairs, and have a decreased lifespan.

Another essential part of testing the new furnace is to make sure it is venting properly. This ensures that the combustion fumes flow directly outside to prevent carbon monoxide from being able to leak back into the home. Our technicians will also check to make sure that all of the various safety switches in the furnace work as they should.

Our Services

With 40 years of experience, Hoff Heating & AC is the top choice for furnace installation services in O’Fallon and the Greater St. Louis area. We are proud to be a Lennox Premier Dealer, and we offer some of the top-rated furnaces in the industry. Once your new furnace is installed, we can also take care of the necessary repairs and maintenance requirements to keep it heating effectively. We also offer professional air conditioning and air quality services. Give us a call for any of your HVAC needs.