Furnace Pressure Switch
A furnace pressure switch is a safety device that ensures dangerous gases like carbon monoxide are vented properly from your home. It’s designed to detect whether the inducer motor is creating enough air pressure to move combustion gases safely out through the vent pipe.
In short, if your furnace isn’t venting correctly, the pressure switch prevents it from turning on — protecting you and your home from potential harm.
When your thermostat calls for heat, here’s what happens:
Why the Furnace Pressure Switch Is So ImportantYou might not think much about it, but the pressure switch is a vital safety mechanism. Without it, your furnace could operate under unsafe conditions — such as a blocked flue or failed exhaust fan — which could lead to carbon monoxide buildup.
Key benefits of the pressure switch include:
5 Common Signs of a Faulty Furnace Pressure SwitchIf you’re in Thornton, CO and your furnace is acting up, the pressure switch might be to blame. Here are some common signs of a bad or malfunctioning switch:
What Causes Furnace Pressure Switch Problems?There are a few common reasons your furnace pressure switch might fail or give false readings:
1. Blocked Vent PipeSnow, debris, or even birds’ nests can block the exhaust vent, preventing airflow and keeping the switch from closing properly.
2. Dirty or Clogged Inducer MotorDust and soot buildup can affect the inducer fan’s performance, reducing the pressure needed to trigger the switch.
3. Cracked or Loose TubingThe rubber tubing connected to the pressure switch can crack, loosen, or fill with condensation — interrupting the pressure signal.
4. Electrical FaultLoose wiring or corroded terminals can cause intermittent or failed connections to the control board.
5. Failed Pressure SwitchLike any mechanical component, the switch itself can simply wear out over time.
How HVAC Technicians Test a Pressure SwitchWhen you call a licensed HVAC professional like HVAC Thornton Pros, our technicians use a multimeter or manometer to test the switch. We’ll verify that:
Can You Replace a Furnace Pressure Switch Yourself?While some homeowners might be tempted to replace the switch themselves, it’s not always a good idea. A malfunctioning pressure switch could be a symptom, not the cause, of your furnace issue. If you replace it without addressing the underlying problem — such as a blocked flue or weak inducer motor — your furnace could still be unsafe to operate.
It’s always best to call a licensed HVAC technician to inspect the entire system and ensure everything is functioning properly.
Professional Furnace Repair in Thornton, COIf your furnace isn’t firing up or you suspect an issue with the pressure switch, don’t wait for a cold night to find out the hard way. At HVAC Thornton Pros, we provide fast, reliable furnace repair across Thornton and the surrounding Colorado areas.
Our team is available to diagnose, repair, and tune up all major furnace brands to keep your home warm, efficient, and safe.
📞 Call (720) 807-4379 today to schedule a same-day service appointment or request a free estimate online at www.hvacthorntonpros.com.
Let our experienced technicians keep your home comfortable all winter long.
Frequently Asked Questions on Furnace Pressure Switch1. What happens when a furnace pressure switch fails?When it fails, the furnace’s control board won’t receive the “all-clear” signal to ignite. The system may lock out or shut down entirely to prevent unsafe operation.
2. How much does it cost to replace a furnace pressure switch?In Thornton, CO, replacing a furnace pressure switch typically costs $150 to $350, depending on the furnace model and labor costs.
3. Can I bypass a furnace pressure switch?No — never bypass or tamper with your pressure switch. It’s a crucial safety feature designed to protect your home from carbon monoxide and combustion hazards.
4. How can I prevent pressure switch issues?Schedule regular furnace maintenance, keep vents clear, and change your air filters frequently to prevent airflow restrictions.
In short, if your furnace isn’t venting correctly, the pressure switch prevents it from turning on — protecting you and your home from potential harm.
When your thermostat calls for heat, here’s what happens:
- The inducer motor starts up to expel any leftover combustion gases.
- The pressure switch senses whether there’s enough airflow.
- If the airflow is adequate, the switch closes, signaling the control board to ignite the burners.
- If not, the switch stays open — and your furnace won’t fire up.
Why the Furnace Pressure Switch Is So ImportantYou might not think much about it, but the pressure switch is a vital safety mechanism. Without it, your furnace could operate under unsafe conditions — such as a blocked flue or failed exhaust fan — which could lead to carbon monoxide buildup.
Key benefits of the pressure switch include:
- ✅ Prevents furnace ignition during unsafe venting conditions
- ✅ Protects against gas leaks and carbon monoxide exposure
- ✅ Ensures proper airflow for combustion
- ✅ Helps maintain furnace efficiency and performance
5 Common Signs of a Faulty Furnace Pressure SwitchIf you’re in Thornton, CO and your furnace is acting up, the pressure switch might be to blame. Here are some common signs of a bad or malfunctioning switch:
- Furnace won’t ignite — The system tries to start but quickly shuts down.
- Error codes or flashing lights — Your control board might display a pressure switch fault.
- Short cycling — The furnace turns on and off repeatedly.
- Clicking sounds — The switch is trying to open and close but isn’t detecting proper airflow.
- No heat — Even though the thermostat is working, the furnace won’t blow warm air.
What Causes Furnace Pressure Switch Problems?There are a few common reasons your furnace pressure switch might fail or give false readings:
1. Blocked Vent PipeSnow, debris, or even birds’ nests can block the exhaust vent, preventing airflow and keeping the switch from closing properly.
2. Dirty or Clogged Inducer MotorDust and soot buildup can affect the inducer fan’s performance, reducing the pressure needed to trigger the switch.
3. Cracked or Loose TubingThe rubber tubing connected to the pressure switch can crack, loosen, or fill with condensation — interrupting the pressure signal.
4. Electrical FaultLoose wiring or corroded terminals can cause intermittent or failed connections to the control board.
5. Failed Pressure SwitchLike any mechanical component, the switch itself can simply wear out over time.
How HVAC Technicians Test a Pressure SwitchWhen you call a licensed HVAC professional like HVAC Thornton Pros, our technicians use a multimeter or manometer to test the switch. We’ll verify that:
- The inducer motor is running properly
- The tubing is airtight and free of obstructions
- The switch opens and closes under the correct pressure
Can You Replace a Furnace Pressure Switch Yourself?While some homeowners might be tempted to replace the switch themselves, it’s not always a good idea. A malfunctioning pressure switch could be a symptom, not the cause, of your furnace issue. If you replace it without addressing the underlying problem — such as a blocked flue or weak inducer motor — your furnace could still be unsafe to operate.
It’s always best to call a licensed HVAC technician to inspect the entire system and ensure everything is functioning properly.
Professional Furnace Repair in Thornton, COIf your furnace isn’t firing up or you suspect an issue with the pressure switch, don’t wait for a cold night to find out the hard way. At HVAC Thornton Pros, we provide fast, reliable furnace repair across Thornton and the surrounding Colorado areas.
Our team is available to diagnose, repair, and tune up all major furnace brands to keep your home warm, efficient, and safe.
📞 Call (720) 807-4379 today to schedule a same-day service appointment or request a free estimate online at www.hvacthorntonpros.com.
Let our experienced technicians keep your home comfortable all winter long.
Frequently Asked Questions on Furnace Pressure Switch1. What happens when a furnace pressure switch fails?When it fails, the furnace’s control board won’t receive the “all-clear” signal to ignite. The system may lock out or shut down entirely to prevent unsafe operation.
2. How much does it cost to replace a furnace pressure switch?In Thornton, CO, replacing a furnace pressure switch typically costs $150 to $350, depending on the furnace model and labor costs.
3. Can I bypass a furnace pressure switch?No — never bypass or tamper with your pressure switch. It’s a crucial safety feature designed to protect your home from carbon monoxide and combustion hazards.
4. How can I prevent pressure switch issues?Schedule regular furnace maintenance, keep vents clear, and change your air filters frequently to prevent airflow restrictions.