Faulty Gas Valve

You will find gas valves on gas-fired hot water and steam boilers, gas furnaces, and gas fired hot water heaters. Modern, state-of-the-art heating systems utilize gas valves that are controlled by an electronic ignition or a printed circuit board. Conversely, older units often have a standing pilot.

When They Fail

Gas valves control the flow of gas from the gas supply line into the heating unit. If your furnace is not producing heat, a faulty gas valve could be the problem. There are several reasons this valve may stop working properly. The valve itself may have simply worn out or may be damaged due to basement seepage or submersion. Alternately, one of the electronic gas ignition components or a glitch in the safety circuit may be to blame. If your furnace has a standing pilot light, the thermocouple could be worn out.

Safety Concerns

Gas fueled heating systems have many built in safety features to prevent your home or business from filling with gas if another part of the furnace is malfunctioning for any reason. Therefore, it may be difficult to figure out exactly what is causing the system to fail. Testing the flow in and out of the valve may indicate the problem lies within the valve itself, necessitating its replacement. However, this may not be the only issue that needs to be resolved.

If it is the gas valve, or any related component, this is a job best left to a professional HVAC technician. Any furnace repair can be problematic, but unlike replacing a thermostat, when you are dealing with the flow of gas into your home, even a small mistake could result in catastrophe.

What to Do

The best way to avoid an unexpected repair during the middle of a cold winter night is to schedule a thorough inspection before the heating season. However, sometimes something just plain wears out. When that happens, reach out to the best, most reliable, HVAC service team in Chicago, IL—the professionals at Heatmasters, where we always put your comfort and safety first!

The draft inducer blower is a relatively new component found on modern furnace units. Added to ensure heating systems are able to comply with the most recent government-mandated efficiency standards, it is designed to facilitate the removal of gases and air from the furnace and out to the chimney.


When the furnace enters start-up mode, the blower removes any gases remaining in the heat exchanger from the previous cycle. This provides cleaner air for combustion as well as helping to prevent soot from clogging the burners. At the beginning of the heating cycle, the blower fan begins spinning 30 to 60 seconds prior to the burners igniting. The fan motor must also run properly, and this function is usually monitored by a safety pressure switch attached to the blower housing.

If at any time, the motor cannot turn on, the furnace will usually shut off and lock out. A blockage in the gas vent flue, a faulty pressure switch, or even a malfunction of the blower itself may also cause the system to shut down.

Fixing the Problem

Due to the fact that most draft inducer blower designs are nearly impossible to rebuild, when the motor (or other component) fails, it is usually necessary to replace the entire blower unit. However, most units manufactured by Carrier and Bryant are exceptions to this rule.

Determining the exact cause of any shut down of your HVAC system is not always as simple as it initially seems. Conversely, some very minor issue may mimic a costly part replacement. Therefore, the best way to diagnose why your furnace is giving you the cold shoulder is to call on an experienced professional. Here in the Chicagoland area, there is no one more reliable or dedicated to your safety and comfort than the highly-trained technicians at Heatmasters.

When your furnace is failing to produce heat, a faulty furnace igniter could be the culprit. The furnace igniter is simply the catalyst that ignites the fuel, lighting the burners, and producing heat in the heat exchanger. If it is not functioning correctly, your furnace will not work as it should.

Types of Igniters

In the past, both furnaces and boilers used pilot lights to ignite the burners. A pilot light is a small, standing flame that is maintained by a connection to a constant flow of gas. This, in turn, will ignite the burners when a larger quantity of gas is released by the gas valve, providing heat whenever it is called for by the thermostat. You may have a pilot light igniter if you have an older model furnace or boiler.

Most furnaces today use electric hot surface igniters, which industry experts agree are more reliable and cost efficient alternatives to pilot lights. A hot surface igniter is electric, eliminating the need for a constant flow of gas to the pilot light, saving energy and money. Hot surface igniters consist of a thin wire made from high-heat resistant metal that glows red hot and produces a spark when the system calls for heat.

Possible Problems

A pilot light can occasionally go out as a result of a draft, requiring it to be manually relit. A dirty or broken thermocouple or sensor can also be the cause of a malfunctioning pilot light.

On the other hand, hot surface igniters have a definite life span. They may last up to five years, but will eventually burn out and need to be replaced. To ensure your igniter lasts as long as possible, maintain your furnace filter by cleaning or changing it as required, and clean carefully around the igniter—but be aware that the wire is very delicate and can easily break if disturbed.

Restoring Heat

It is possible to relight a blown out pilot, and even replace a thermocouple or hot surface igniter yourself—just make sure to consult the furnace or boiler owner’s manual first.

On the other hand, the simplest, quickest, and most reliable way to get your heating system up and running properly is to call on the expert technicians at Heatmasters. We will make sure the job is done correctly, keeping you and your family safe, warm, and comfortable. Furthermore, having a professional check out your HVAC system seasonally is highly recommended. Proper maintenance reduces, and can even eliminate, costly and inconvenient emergency repairs.


One of the most common causes of an otherwise fully operative furnace failing to produce heat is a problem with the flame sensor.

What a Flame Sensor Does

The flame sensor is a safety feature that is designed to protect your family and your home from dangerous conditions that can arise after the gas is ignited. It is composed of particular metals that create an electrical current in the presence of a flame. The sensor is designed to detect whether or not the fuel is being burned properly by the last burner in the group of burners.

If the flame is steady at the last burner, this indicates that the proper ratio of fuel and air is being distributed to each of the burners, and a safe burning environment is assumed. When no flame is detected, it could mean that any one of the burners is not working properly. The flame sensor is designed to signal the control board, and the control board shuts down the system.

Because any system can produce an occasional false reading, your furnace may try to restart two or three times, and then turn off for a period of several hours, or even permanently until the condition is addressed and the control panel is reset.

Possible Causes of a Flame Sensor Malfunction

There are two possible reasons a flame sensor will not relay the proper information to the control board. The most common is that it is dirty. Because burning fuel of any kind produces trace amounts of moisture, over prolonged exposure to these conditions, metal will rust. Since your sensor is made of metal, rust can build up, preventing proper sensing of the flame.

The other possible issue is a cracked insulator or otherwise defective sensor. It may be that a short has developed in the electrical component, stopping communication with the control board.

What to Do

The best thing to do if you hear your furnace starting and stopping two or three times, and it still doesn’t begin to cycle, is to call on our expert technicians at Heatmasters. We can clean or replace the defective sensor, safely restoring warmth and comfort to your home or business. Count on experience. Count on quality. Count on Heatmasters!