Sunset Air Blog: Posts Tagged ‘Furnaces’

What Causes Delayed Ignition in a Gas Furnace?

Monday, November 27th, 2023

If you’re a frequent reader of our blog, you’ll know that we often discuss alarming sounds in a furnace that require prompt attention. One of these is a booming sound in a gas furnace. That’s because this sound is often made by a gas furnace’s delayed ignition. What you’re hearing is literally a mini explosion when something is impeding the furnace’s ability to ignite when it’s supposed to. 

There are many possible causes for delayed ignition. No matter what the cause is, one thing is for certain: delayed ignition is something that should be addressed ASAP. Delayed ignition can potentially lead to a fire in your home. It can also cause damage to your furnace when it’s subjected to these constant mini-explosions. Let’s go over 4 possible causes.

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Why Is My Furnace Making Strange Noises?

Monday, November 9th, 2015

It can be somewhat alarming when your furnace starts making unusual noises. Your mind may dream up all sorts of nightmare scenarios that might be happening to your furnace. Really, though, how much trouble your furnace is in depends on the type of sound you’re hearing. Let’s run through some of the more common strange sounds you are likely to hear coming from your furnace.

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Short-Cycling and Its Effects on Your Furnace

Monday, April 6th, 2015

Have you noticed your furnace turning itself on and off every few minutes? If so, you have a problem. That behavior is known as “short-cycling,” and it can be quite harmful to your furnace if allowed to continue for any length of time. If you notice your furnace short-cycling, you should turn it off and call for a professional to look at it. If you’re interested in preventing it from happening in the first place (and you should be) then read on. Let’s examine the primary cause of short-cycling, and what it can do to your furnace.

Clogged Air Filter

Every furnace has an air filter installed in the return duct of the air handler. This filter is designed to protect the furnace by capturing any dust or other particles that might otherwise damage the system. Though the air filter is quite good at this job, it can become clogged with these particles if it’s not cleaned or replaced every few months. If that happens, it will restrict the flow of air into the furnace.

When the air flow into the furnace becomes obstructed, the temperature inside the system rises. Eventually, the furnace will overheat. This activates the limit switch, which shuts down the furnace as a safety measure to prevent it from damaging itself. Unfortunately, the limit switch cannot address the cause of the overheating. As soon as the furnace restarts, the clogged air filter will cause it to overheat again and the limit switch will cause it to shut down again.


The startup process is the most stressful part of the entire furnace cycle. It is during that time that the furnace attempts to reach the target temperature as quickly as possible. After the temperature is reached, it eases off and only makes the occasional adjustment to maintain the climate. When the furnace becomes locked in an endless startup process, it is put under far more stress than it was designed to handle. This can cause the heat exchanger to rapidly wear out and develop cracks, requiring replacement. The entire system will be put at greater risk for a breakdown, and its lifespan will be drastically reduced.

If you suspect your furnace of needing repairs, call Sunset Air. We provide furnace repairs throughout Olympia, WA. 

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Why Do Furnaces Need an Exhaust Flue?

Friday, November 28th, 2014

You’ve probably noticed your furnace’s exhaust flue, that pipe that extends away from your ductwork and through the wall to the outside of the house. The concept of an exhaust flue is thousands of years old, it’s the whole reason fireplaces have chimneys. In the context of a modern furnace, however, it may seem odd for the exhaust flue to have so much importance. Most furnaces, depending on their fuel source, don’t produce smoke. So what’s the point? Let’s examine the actual byproducts of today’s furnaces, and why the exhaust flue is necessary to get rid of them.

Incomplete Combustion

Every furnace works by burning some kind of fuel to produce heat, whether it be wood, gas, or oil. Combusting fuel can create heat and energy quite easily, as evidenced by the fact that much of our transportation technology relies on it. Unfortunately, it’s not an efficient process. Combustion is often incomplete, resulting in byproducts of the burnt fuel being created. These byproducts are almost entirely pollutants.

Combustion Byproducts

There are a number of combustion byproducts common to furnaces. The three major ones are carbon monoxide, nitrogen dioxide, and sulfur dioxide. All of these are toxic gases, and should be avoided as much as possible. Unfortunately, carbon monoxide is completely undetectable to human senses. This makes it the most dangerous of the three, as the other two have unpleasant odors that allow them to be more easily avoided.

Carbon monoxide works by displacing the oxygen in a person’s blood stream. In high enough concentrations, this can cause suffocation. Carbon monoxide poisoning is among the most common types of fatal air poisonings on the planet. Common symptoms of exposure include headaches, nausea, dizziness, and fatigue. If you suddenly start experiencing any of these symptoms, especially while the furnace is on, get out of the house and call emergency services. This is the biggest reason why furnaces need an exhaust flue. Without a safe way to vent these byproducts out of the house, they can become trapped and poison the people inside.

If you think your exhaust flue is having issues, call Sunset Air. We provide heating repair services throughout Olympia.

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3 Potential Reasons Why Your Furnace Is So Expensive to Run

Friday, October 24th, 2014

As we head toward winter, more and more people are turning on their heating systems. If you’ve noticed a big jump in your heating bill as compared to last year, you may need to consider some reasons as to why your heating has become so expensive to run. Our Sunset Air technicians have put together a short list of reasons that can account for a sudden jump in energy costs, as outlined below.

Reason 1: Faulty Ductwork

Your ductwork in an integral part of your heating system, but it can be overlooked or even ignored because it isn’t as visible as other parts of the system. Faulty ductwork – ductwork with significant cracks, holes or disconnections – can account for up to 30% of your home’s total air loss. Your furnace will work to compensate for this loss by working harder, which forces it to use more energy.

Reason 2: No Programmable Thermostat

A programmable thermostat allows you to set a heating program for different times and days, as far out as a week. You can program your heater to maintain more moderate temperatures when your home is unoccupied, such as during the work week, or at night when everyone is in bed. It can be difficult to remember to change your thermostat on your own, and the EPA estimates that for every degree you can lower your thermostat during the winter, you can save up to 3% on your energy costs.

Reason 3: Insufficient or Poor Maintenance

Every season your heating system operates causes it incurs a certain level of wear and tear. Without annual maintenance, this wear and tear is not taken care of, and will continue to run down your system season after season. Maintenance helps reduce your energy usage because it is cleaned and adjusted, and all moving parts are lubricated, which allows the system to work optimally. When your system works optimally, it doesn’t use extra energy to work.

If your heating bills have taken you by surprise, call Sunset Air today and let a trained HVAC technician in Olympia, WA help you find out what is happening with your furnace.

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Safety Features on Your Furnace

Wednesday, March 19th, 2014

Gas-powered furnaces can pose health hazards, but not at the level you may think. In general, conventional wisdom has far exaggerated the potential dangers of gas furnaces, which are no more a safety risk than other heating systems as long as they receive regular maintenance. If you take care of your gas furnace as you would any heating system in Tacoma, WA, you should encounter few problems with it, safety or otherwise. Look to Sunset Air for an excellent maintenance program for your furnace and air conditioner.

The reason that gas furnaces rarely create health hazards is because they have a number of special safety features installed in them that prevent gas leaks and the risk of explosions. Let’s go over a few of them:


One of the potential problems a furnace could have is flooding of the combustion chamber with unburned gas. If the pilot light of a furnace goes out (not all furnaces have pilot lights, which is another safety feature), unburned gas from the burner can fill up the combustion chamber and pose the threat of an explosion from even a small spark. To prevent this, a device called a thermocouple registers the heat of the pilot light. An electric current runs through the thermocouple—two linked pieces of different metal—that increases with the temperature. When the pilot light goes out, the thermocouple’s voltage vanishes, which causes the gas valve to shut off, preventing any more burned gas from entering the chamber.

Mercury sensor

This device has started to replace the thermocouple as the method of determining if the pilot light is still on. A mercury flame sensor protruding into the pilot light drives up the mercury in the device, which makes an electrical connection that keeps the gas valve open. When the pilot goes out, the mercury falls, the connection fails, and the valve closes.

Furnace fan limit switch

This safety mechanism prevents the furnace from overheating. The switch is located beneath the plenum of the furnace and registers its temperature. When the temperature rises above a set level (which the owner can change), the limit switch shuts off the burner. As the temperature drops, the switch first turns off the blower at a lower level, increasing the speed of the temperature decline, and only when the temperature reaches the lowest setting does the switch reactivate the blower.

It’s important that all these safety mechanisms work the best they can, and that means regular maintenance. Technicians will find out when thermocouples or mercury sensors need replacement, and catch where the furnace might develop possible safety-threatening malfunctions. Sunset Air can help you repair and maintain your heating in Tacoma, WA so you’ll always have a safe and effective furnace working for you.

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How Does the AFUE Rating Affect My Furnace?

Tuesday, January 28th, 2014

If you’ve ever installed or upgraded your furnace, you’ve probably heard the term “AFUE” used to describe its efficiency. Here in Tacoma, heating installation services will talk up high AFUE ratings, particularly when selling a more expensive model to you. That still doesn’t explain what an AFUE rating is or how it applies to heating. It’s reasonable to ask “how does the AFUE rating affect my furnace?” We can provide a few answers below.

AFUE stands for “Annual Fuel Utilization Efficiency,” which marks how efficiently the furnace uses energy. It’s listed as a percentage, representing the amount of energy the unit takes in divided by the amount it actually uses on heating. For example, a unit which uses 50,000 BTUs (British Thermal Units) of energy and creates 40,000 BTUs worth of heat has an AFUE of 40,000/50,000 or 80%. That means 80% of the energy is actually going to heat the home, with the other 20% being lost to waste and inefficiency.

In light of that, it’s obviously beneficial to use a furnace with the highest AFUE rating it can have. As time goes on, a furnace’s AFUE rating goes down, since parts wear out and the aging components need to work harder in order to do the same job. When the time comes to replace your furnace, it’s beneficial to look for one with higher AFUE rating, since it will save you money in the long run. Say your current furnace uses 100,000 BTUs and produces only 50,000 BTUs of heating power (an AFUE rating of 50%). Replacing it with a similar model with an AFUE of 90% — generating 90,000 BTUs of heating power for 100,000 BTUs used — means a savings of 40,000 BTUs, increasing your overall efficiency by 80% and saving you a great deal of money in the bargain.

Knowing how the AFUE rating affects your furnace will allow you to make an informed decision when purchasing a new one. The Tacoma heating installation experts like the ones at Sunset Air can provide further advice. We’re dedicated to your complete satisfaction and can find a new furnace for you with an improved AFUE rating that doesn’t break your bank. Give us a call today to set up an appointment!

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