In a forced air system, the furnace device is important for safety and ensuring the system works well. Before turning on the furnace, there are a few factors on the checklist, such as in the working status of the ventilation system and the connection of the pressure switch to the furnace’s vent pipe that reacts according to the changes in air pressure.
The pressure switch monitors the air pressure in the vent pipe by preventing the furnace from turning on if the pressure drops below a certain level. It will rest assured nothing goes wrong in any situation.
What is Furnace Pressure Switch?
The furnace pressure switch is connected to a control board that controls its working function by regulating the temperature and ensuring everything runs smoothly. The switch is designed to automatically close when the furnace is not running and vice versa. And in the end, it will shut down when the furnace reaches its normal operating pressure.
Monitoring or checking the furnace pressure switch at regular intervals is important. Because the furnace won’t turn on or unexpectedly turn off while running if the switch is not working properly. In such a scenario, get it inspected by a professional, as it is a sign of malfunctioning.
What is the Working Furnace Pressure Switch?
A working furnace pressure switch monitors the pressure inside the furnace’s vent system and ensures that the furnace’s ventilation system is functioning properly before allowing the furnace to turn on.
When you turn on the furnace, the pressure inside the vent system will change as its starts to draw air through the return ducts and blow hot air through the supply ducts. A pressure switch is installed to detect the changes in pressure and respond accordingly.
The pressure switch is conveniently linked to the furnace’s vent pipe and features two ports for a seamless connection. One port is connected to the vent pipe, and the other port is connected to the control board. The pressure switch automatically turns on when you fire up the furnace. It signals to the control board that all systems go and the furnace is prepared to run smoothly.
What is the Importance Of a Pressure Switch in Your Furnace?
The primary purpose of the pressure switch is to ensure that the furnace’s ventilation system is working properly before allowing the furnace to turn on. It monitors the air pressure in the vent pipe and prevents the furnace from turning on if the pressure drops below a certain level, which could indicate a blockage in the vent pipe.
It also helps to prevent the build-up of dangerous gases, such as carbon monoxide, inside the home by shutting off the furnace if it detects a problem with the venting system. This can save lives and also protect your home from potential hazards.
Also, having a pressure switch that works well ensures the furnace works well and efficiently. Ensure that the pressure switch is in good working condition; otherwise, your furnace could malfunction and shut off unexpectedly or not turn on. This can decrease energy efficiency and drive up energy costs significantly!
In short, the pressure switch is an important safety device that plays a vital role in the furnace’s proper functioning and the home’s protection. It is important to check and test the pressure switch often to ensure it works correctly and the furnace works safely.
Types of Furnace Pressure Switch
Different kinds of pressure switches for furnaces are made to meet different furnace systems requirements. These include:
1. Single Stage Conventional Furnace
This pressure switch is specially crafted for single-stage conventional furnaces, usually found in older homes with a single heat setting. It’s an efficient and effective addition for any home, old or new. The pressure switch in these systems is used to detect changes in pressure in the vent pipe and shut off the furnace if necessary to protect against dangerous gas build-up.
2. Single Stage Condensing Furnace
This type of furnace pressure switch is designed for use in single-stage condensing furnaces, which are more efficient and typically found in newer homes. These pressure switches are similar to those used in conventional furnaces but are designed to be more sensitive to changes in pressure and to shut off the furnace more quickly in case of a problem.
3. Two-Stage Furnace
These pressure switches are more advanced than those used in single-stage systems with two heat settings, high and low.
4. Modulating Furnace
This type of furnace pressure switch is used in modulating furnaces, which can adjust their heat output to meet the demands of the home. These pressure switches are very advanced. They can keep track of and react quickly to changes in pressure. This ensures the furnace runs as efficiently as possible and keeps you comfortable.
You need to pick up a pressure switch that is compatible with the furnace system to ensure proper operation and safety.
Why Does Furnace Pressure Switch Fail?
Regular checkups of a furnace pressure switch can prevent serious malfunctions from occurring, which happen for various reasons. Some of the most common reasons for furnace pressure switch failure include:
1. Blockage in Inducer Fan
The inducer fan is responsible for drawing in air from the outside and blowing it into the furnace. If the inducer fan becomes blocked, it will not be able to draw in enough air and the pressure switch will not close, preventing the furnace from turning on.
2. Blockage in Flue/Chimney
The flue or chimney is responsible for venting combustion gases outside of the home. If the flue or chimney becomes blocked, the pressure switch will not close and the furnace will not turn on.
3. Crack/Hole in Suction Tube
The suction tube connects the pressure switch to the vent pipe. If there is a crack or hole in the suction tube, the pressure switch will not function correctly, preventing the furnace from turning on.
4. Bad/Loose Wire Connection
The pressure switch is connected to the furnace’s control board with wires. The pressure switch will not function correctly if the connections become loose or corroded.
5. Water Built Up In The Inducer Fan Housing
High-efficiency furnaces have condensate traps that prevent water from building up inside the inducer fan housing. If that trap clogs or there is a issue with the drainage it can lead to water built up in the inducer fan housing, this will cause the pressure switch to fail.
6. Loose Suction Tube
If the suction tube is not securely connected to the pressure switch or the vent pipe, it may cause the pressure switch to fail.
7. Bad/Shorted Switch
The pressure switch may fail due to wear and tear or an internal malfunction, preventing the furnace from turning on.
8. Inducer Fan Running Too Slow
If the Inducer fan is running too slow, the pressure switch may not close, preventing the furnace from turning on.
9. Inducer Fan Motor Is Bad
The inducer fan motor may fail, causing the fan not to run at all, This will prevent the pressure switch from closing and the furnace will not turn on.
How to Test the Working Condition of a Furnace Pressure Switch?
It is important to test the pressure switch for smooth operational working. Here are a simple steps to check its working condition.
1. Switch off the Power
Before performing any maintenance on the furnace, it’s important to ensure that the power is turned off to prevent electrical shock or damage.
2. Check the Pressure Switch Hose
Inspect the hose that connects the pressure switch to the vent pipe to see any visible signs of damage or obstruction.
3. Look at the Obstructions in the Hose
Check the hose for any blockages or debris that might be preventing proper airflow.
4. Inspect the Hose Port
Inspect the hose ports on the pressure switch and ensure they are clear of any blockage or damage.
5. Examine the Furnace Cover
There shouldn’t be any cracks or holes in the furnace cover to avoid any air from escaping.
6. Check for Vent Blockage
Inspect the vent pipe and the flue or chimney for any blockages that might be preventing proper airflow.
7. Check the Switch for Resistance
A multimeter checks the pressure switch for resistance by setting the meter to the “resistance” function and touching the probes to the switch terminals. The switch should show continuity.
8. Check the Furnace’s Operation
Once you have finished your inspections and made any necessary repairs, turn the power back on and test the furnace’s operation. If the furnace still isn’t working, it might be time to get a professional involved for further inspection and repair. It’s always better to be safe than sorry and handle any potential problems before they worsen.
Are There Any Troubles With Furnace Pressure Switch Usage?
Furnace pressure switches can sometimes experience a few issues, and it’s important to be aware of them. From blocked or clogged vents to loose wiring, these common problems can make your heating system work much less well.
1. Loose Hoses
The hose that connects the pressure switch to the vent pipe can become loose over time, preventing the switch from functioning properly. If the hose is loose, it will not be able to properly detect changes in pressure in the vent pipe, which can cause the furnace not to turn on or to shut off unexpectedly.
2. Debris on Switch
Any dust or lint, such as debris accumulating on the pressure switch, can cause a major problem in the switch’s functioning property. It can stop the switch from turning on and off when required. It needs to be resolved with an immediate solution.
3. Crack or Hole in the Tube
When there is a crack or hole in the tube connecting the pressure switch and vent pipe, it will cause disruption in the pressure detection. In such a scenario, the switch won’t close, preventing the furnace from turning on.
4. Broken Switch
The pressure switch is a mechanical device that can wear out over time. If the switch gets broken, it won’t be able to detect changes in pressure as it should. This will keep the furnace from turning on or off by itself.
How To Replace a Furnace Pressure Switch?
Replacing a furnace pressure switch can be complex and is best done by a professional HVAC technician to ensure that it is done correctly and safely. However, if you wish to try to replace it yourself, here is a general guide on how to do so:
1. Switch off Power to the Furnace
Before performing any maintenance, it’s important to ensure that the power is turned off to prevent electrical shock or damage to the furnace.
2. Locate the Pressure Switch
The pressure switch is typically located near the inducer motor or the vent pipe. It is a small cylindrical device with two wires coming out of it, connected to the control board.
3. Disconnect the Wires
Take time to detach the wires from the pressure switch terminals with a screwdriver. Remember which wire is connected to which terminal, as you’ll need to reattach them in the exact same order later.
4. Remove the Old Switch
A bracket usually holds the pressure switch in place. Remove the bracket by loosening the screws and gently wiggle the switch out.
5. Install the New Switch
Carefully insert the new switch into the bracket, lining up the screw holes. Replace the bracket, and Tighten the screws to hold the switch in place.
6. Reconnect the Wires
Reconnect the wires to the new switch in the same manner as they were connected to the old switch.
7. Turn the Power Back On
Make sure your furnace is connected to the switch and turn the power back on! Now you can test that everything works and your furnace is ready to go!
It’s important to note that the new pressure switch must be the same type and rating as the old one. If you need help with the type of switch you need, please refer to the furnace’s documentation or seek the help of a professional HVAC technician. And also please be aware that this task requires some technical know-how and is potentially dangerous if not done properly, it’s always better to seek professional help.
Furnace Switch FAQs
Ans: There could be several explanations as to why your furnace isn’t firing up. Some possible causes include: a lack of fuel, a malfunctioning thermostat, a broken or clogged pressure switch, a blocked or dirty flame sensor, a failed ignition control module, or a clogged air filter. It is best to have a professional HVAC technician diagnose and fix the issue.
Ans: It is not recommended to run a furnace without a pressure switch. The pressure switch is a great safety feature that ensures your furnace’s ventilation system works well. It will only allow the furnace to turn on if it detects the correct amount of pressure! Amazing! Without a pressure switch, dangerous gases such as carbon monoxide may build up inside the home, which can be potentially fatal.
Ans: Yes, a pressure switch can get clogged. The pressure switch is connected to the furnace’s vent pipe, and if the pipe becomes clogged with debris, it can prevent the switch from functioning properly. This can cause the switch not to close and prevent the furnace from turning on or shutting off unexpectedly. Regular maintenance & cleaning of the vent pipe and pressure switch can go a long way in avoiding this problem. It’s an easy and effective way to keep your equipment running smoothly!
Conclusion
In conclusion, the furnace pressure switch is an important safety device that is used in forced air heating systems. Before letting the furnace turn on, it checks to ensure the ventilation system works well. The pressure switch is connected to the furnace’s vent pipe and triggered by air pressure changes.
When pressure drops below the standard level, a switch automatically opens to prevent the furnace from turning on. This is an important safety feature because it prevents the furnace from turning on if there is a blockage in the vent pipe, which could cause dangerous gases to build up inside the home. Keep in mind that pressure switches can sometimes malfunction due to a variety of causes like hoses that are too loose, debris accumulation on the switch, tiny cracks or holes in the tubes and even broken switches. If you suspect that you have an issue with your pressure switch, it’s highly recommended to have it looked at by a professional HVAC technician.
