Furnaces Keeping You Warm & Cozy All Winter Long, Guaranteed

Monroe Township Furnace Services

Your Heating Experts, Serving All of Central New Jersey and the Jersey Shore

In New Jersey, where the temperatures drastically change throughout the year, you depend on your heating system to keep you and your family comfortable year-round. Any piece of equipment with constant use will go through normal wear and tear, causing your system to possibly malfunction or break down. Guaranteed Service is here for you through all of this, whether you need annual maintenance or emergency service, anytime, any day.

For more information about our heating services in Central New Jersey and the Jersey Shore, call (732) 412-1134 or contact us online.

How a Furnace Works

As we head into winter, it’s a good idea to learn a thing or two about the machine that will provide you with heat and comfort throughout the cold, winter days—most likely, a gas furnace. The more you understand how a furnace works, the better you can troubleshoot if something goes wrong. According to the Department of Energy, space heating accounts for roughly 45% of energy bills paid by U.S. homeowners, so it’s no wonder why people want to know more about how furnaces work.

To be clear, you may have a different heating system, such as a boiler, heat pump, or active solar heating. If your heating system heats water and you have radiators, you have a boiler. A heat pump is basically an air conditioner that works in reverse. Keep in mind that many homes have a hybrid heating system, which combines the energy efficiency of heat pumps for mild weather with the powerful heating capacity of furnaces during more extreme temperatures.

Not all furnaces use natural gas, although most do. Your furnace may run on propane, heating oil, or electricity.

Understanding how your furnace works will help you troubleshoot it and potentially avoid an expensive HVAC service call. Sometimes, you can quickly solve the problem yourself. Other times, you can easily show the problem to your Monroe Township heating specialist, saving time and frustration. As an added bonus, you’ll also impress the technician with your knowledge.

The sequence of operation may vary depending on type or brand.

But for the most part, manufacturers have all gone to a hot surface or direct spark ignition, and the sequence of operation is as follows:

  1. There is a heat call from the thermostat
  2. The control board does a safety check (limit switches, roll out switches)
  3. The inducer motor comes on
  4. The pressure switch must close to go to the next step
  5. The hot surface ignitor begins getting hot or the direct spark ignitor begins to spark
  6. The gas valve opens
  7. The furnace lights
  8. The flame sensor senses flame
  9. Within 30 seconds to 1 minute, the blower motor comes on
  10. Once the thermostat is satisfied, the burner shuts off

If the inducer comes on but your hot surface ignitor never glows, there is a good chance that you have a bad pressure switch or your vent motor is not moving enough air (vent pipe stopped up, blower wheel stopped up).

Two-Stage Heating

Two-stage heating means the furnace has two levels of heat output: high for cold winter days and low for milder days. Since the low setting is adequate to meet household heating demands 80% of the time, a two-stage unit runs for longer periods and provides more even heat distribution.

Longer, low-capacity operation has many advantages, such as:

  • Consistent comfort: Two-stage heating eliminates the temperature swings associated with standard furnaces, regulating temperature to within as little as one degree of the thermostat setting.
  • Quiet operation: Two-stage furnaces start in the first stage, when the amount of heat required is lower, instead of full capacity all at once. That means there’s no sudden “kick” or blast of air.
  • Improved air filtration: Low-speed operation allows your filters to capture more contaminants (because air is constantly passing through them), so you can breathe easier.
  • Efficient performance: Because the furnace operates mostly in its lower-capacity first stage, it burns less fuel than a standard furnace that always runs at full capacity and shuts off when the heating demand has been met.

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Furnace Heat Exchangers

Your furnace heat exchanger is arguably the most important part of the entire system. It’s at the heart of the system, and it’s what generates the warmed air.

As the air inside the furnace and around the heat exchanger warms to very hot temperatures, the metal inside of the exchanger expands and contracts.

However, over the course of multiple years and multiple winters of use, all that expansion and contraction of metal has the potential to cause the heat exchanger to crack. Even a small crack can be a problem since it can result in carbon monoxide gas being leaked into the home’s air ducts. Not every crack will cause a carbon monoxide leak, but every leak needs to be investigated and repaired when it happens.

To make sure that your exchanger and furnace are safe to operate this winter, you’ll want to schedule a heating tune-up. Regular maintenance means that a technician is doing a thorough inspection to check for the signs of exchanger problems. If there are any problems with the exchanger or furnace as a whole, you’ll be able to address them before the coldest months of the year—or before the furnace becomes a safety hazard to your home.

Flame Sensors

To ensure that the gas has ignited on a hot surface ignition system, the furnace utilizes a “flame sensor” to “sense” the flame. If the primary or ignition board does not sense that a flame has been established, in just a few seconds the board will de-energize the gas valve to stop the flow of gas to the burners. If a flame is not established, most boards will retry a set number of times before going into “lockout.”

The flame sensor is just a small metal rod with ceramic about halfway down it and is usually located at the opposite end of the burners from the hot surface igniter. This is done to ensure that all burners have lit. Often, these sensors collect debris and ash from the burning process and this debris acts as an insulator, not allowing current to flow and causing the module to lock out the system. Usually, when a dirty sensor is the problem, a furnace will run through its ignition sequence, ignite for four to six seconds, and then drop the flame out and start over. These sensors can be cleaned with steel wool or a very fine emery cloth. Using too rough a sandpaper will put grooves in the metal sensor and these grooves will collect debris and ash much faster.

Draft Inducer Motors

As the furnace enters start-up mode, the draft inducer blower begins to purge the heat exchanger of gases that may have remained in that area during the furnace’s previous heating cycle. This makes the air in the area cleaner at the time of combustion and also prevents furnace burners from becoming clogged with soot. By improving the quality of air moving through the furnace, the draft inducer blower helps improve the efficiency of the system.

When a furnace begins a new cycle, the draft inducer blower fan begins with whirring 30 to 60 seconds before the furnace burners actually ignite. The fan motor must also run properly and usually has a safety pressure switch connected to the fan housing. Pressure switches ensure the motor is running according to the manufacturer’s specifications. If the inducer fan motor cannot turn on, the furnace will generally shut off and lockout. Other reasons why the draft inducer blower may ultimately shut down a furnace include a faulty pressure switch, a bad rubber tube component, or there may be a blockage in the gas vent flue, or even that the blower itself may not be working properly.

The Hot Surface Ignitor

The hot surface ignitor is an electric resistant element, much like a cooking element on an electric stovetop. When energized, they become glowing red hot to ignite the gas from the burners. These ignitors are fragile and any break in them will break the circuit to the resistant heater and it will fail.

When changing an ignitor, it is important to take care not to touch the element because the oil from your skin can cause the element to deteriorate.

Operating under normal conditions, a hot surface ignitor will last for three to five years (Silicon Nitride lasts about twice as long). During that time, ignitors will eventually crack and need to be replaced. Like a light bulb, they are a regular replacement item.

A good hot surface ignitor will have a resistance of 40 to 90 ohms. Greater than 90 ohms indicates a failing or failed hot surface ignitor. Disconnect it and measure the voltage coming from the controller. A good reading is 115 to 120 VAC.

Our Comprehensive Services

At Guaranteed Service, our highly skilled Monroe Township heating experts are extremely knowledgeable when it comes to furnace parts and inspections.

We proudly offer the following services to ensure that you and your family remain warm all winter long:

To schedule an appointment, give us a call at (732) 412-1134 or contact us online. Don’t forget to ask about our Comfort Club, which can help you save money on routine maintenance!

Our Pledge:

As an Employee of Guaranteed Service
  • I will always ask the customer at the end of my visit if they are completely satisfied with my visit and the service provided. If they are not, I will do everything in my power to make sure that they are.

  • I promise not to mislead or offer any customer products or services that they do not need or want.

  • I promise to always be ethical and do the right thing, every time.

  • I promise to take personal responsibility for the satisfaction of every customer and will follow all company policies and procedures at all times.

  • I will provide every customer, regardless of size of project, with every available option, which will allow them to make the repair or replacement decision that best suits their needs.

  • I promise to always use my technical knowledge and skill to diagnose all of our customers issues as efficiently and quickly as possible, while providing constant updates to our customer every step of the way.


  • Best HVAC experience I’ve ever had. “The guys at Guaranteed are the best. Al Giordano was friendly, on time and knowledgeable. He helped us pick out the best system for our home. Brian and Nick installed the system in one day. They were efficient, respectful and clean. The job came out better than I could’ve imagined. Best HVAC experience I’ve ever had.”

    - Sebastian C.
  • I will definitely use them again! “Truly great service, Joe is an excellent technician. He took the time to explain everything he was doing and answered all of my questions. I’m so glad I took advantage of the tune-up offer that Guaranteed Service was offering. I will definitely use them again for my maintenance service in the future and would highly recommend this company.”

    - Susan C.
  • Courteous, Professional and Efficient! “One of the best companies that I have ever worked with! From my first phone call to the final walk through, everything was impeccable! Al Giordano
    was just amazing, explained everything upfront and took the time to answer all my questions and address my concerns. Jason, Brian and Nick were fantastic and I cannot stop raving about them to my friends and family! I would recommend them over and over again, courteous, professional and efficient! Call Guaranteed Service, you will not be disappointed!”

    - Lyndell P.

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