How Many Watts to Run Furnace on Generator? You Won’t Believe This!

Winter is coming, and with it, the potential for power outages. If you live in an area prone to storms or rely on a generator for backup power, knowing how many watts your furnace needs is crucial. This guide will walk you through determining the wattage requirements for your furnace and provide helpful tips for choosing the right generator for your needs.

Understanding Furnace Wattage

The wattage your furnace needs depends on several factors, including:

• Furnace size: Larger furnaces require more power to operate.
• Heating capacity: The BTUH (British thermal units per hour) rating indicates the amount of heat your furnace can generate. Higher BTUH ratings generally require more wattage.
• Efficiency: Newer, more efficient furnaces use less energy to produce the same amount of heat, resulting in lower wattage requirements.
• Auxiliary equipment: Components like blower motors, circulating pumps, and electronic control systems also consume power.

Finding Your Furnace’s Wattage

The easiest way to find your furnace’s wattage is to consult the manufacturer’s manual or the unit’s nameplate. The nameplate is typically located on the furnace itself, often near the electrical connection. It will list the voltage and amperage, which you can use to calculate the wattage using the following formula:

Watts = Volts x Amps

For example, if your furnace operates on 240 volts and draws 20 amps, the wattage would be:

240 volts x 20 amps = 4800 watts

Estimating Furnace Wattage

If you don’t have access to the furnace’s documentation, you can estimate the wattage based on the furnace’s BTUH rating. A general rule of thumb is that for every 10,000 BTUH of heating capacity, the furnace requires approximately 1,000 watts.

For instance, a 60,000 BTUH furnace would need around 6,000 watts. However, this is just an estimate, and it’s always best to consult the manufacturer’s specifications for accurate wattage requirements.

Choosing the Right Generator

Once you know your furnace’s wattage, you can select a generator that meets its needs. Here are some key considerations:

• Generator size: Choose a generator with a wattage rating that exceeds your furnace’s requirements. A larger generator will provide enough power to run your furnace and other essential appliances.
• Fuel type: Generators are available in various fuel options, including gasoline, propane, natural gas, and diesel. Consider your fuel availability and storage options when making your choice.
• Start-up power: Generators have a higher power output during startup, known as “surge” power. Ensure your generator’s surge power rating is sufficient to start your furnace.
• Transfer switch: A transfer switch is essential for safely connecting your generator to your home’s electrical system. It prevents backfeeding, which can be dangerous and damage your generator or appliances.

Running Your Furnace on a Generator: Safety Tips

• Professional installation: Always have a qualified electrician install your generator and transfer switch.
• Proper ventilation: Generators produce carbon monoxide, so ensure adequate ventilation to prevent buildup.
• Regular maintenance: Regularly check your generator’s fuel levels, oil, and filters.
• Don’t overload the generator: Avoid running too many appliances simultaneously, as this can overload the generator and cause damage.
• Follow manufacturer instructions: Always refer to your generator’s manual for operating instructions and safety guidelines.

Generator Sizing for Multiple Appliances

If you need to power multiple appliances in addition to your furnace, you’ll need to calculate the total wattage required. Here’s a simple way to estimate:

1. List all appliances: Write down each appliance you want to run on the generator, including the furnace.
2. Find wattage: Look up the wattage for each appliance in its manual or online.
3. Add up wattages: Sum the wattage of all the appliances to get the total required wattage.
4. Add a safety margin: Increase the total wattage by 20-30% to account for startup surges and potential power fluctuations.

Key Factors for Generator Sizing

• Peak demand: Consider the peak demand for power during the coldest days. Your furnace will likely run at its highest capacity during extreme weather conditions.
• Future needs: Think about future appliance additions or upgrades that might increase your power requirements.
• Backup power duration: Determine how long you need your generator to run in case of a power outage.

The Importance of a Whole-House Generator

For comprehensive protection against power outages, a whole-house generator might be a better option than a portable generator. A whole-house generator automatically starts when power is lost, providing uninterrupted power to your entire home. This ensures your furnace, lights, appliances, and other essential systems remain operational during outages.

Beyond the Furnace: Generator Power for Other Appliances

While your furnace is a major consideration, remember that other essential appliances may also require power during a power outage. These could include:

• Refrigerator/Freezer: Keep food fresh and prevent spoilage.
• Well pump: Ensure water supply for drinking and sanitation.
• Lighting: Provide safety and visibility within your home.
• Security system: Maintain home security and deter potential intruders.

Choosing the Right Generator: A Final Word

Selecting the right generator for your needs depends on various factors, including your furnace’s wattage, the size of your home, and the appliances you want to power. It’s crucial to consider your specific requirements and consult with a qualified electrician for personalized guidance.

Frequently Discussed Topics

Q: Can I run my furnace on a small generator?

A: It’s possible to run a small furnace on a small generator, but it’s not recommended. Small generators typically have limited wattage output and may not be able to handle the demands of your furnace, especially during cold weather.

Q: How much wattage do I need for a 90,000 BTUH furnace?

A: A 90,000 BTUH furnace would likely require around 9,000 watts, but it’s best to consult the manufacturer’s specifications for accurate wattage requirements.

Q: What is the difference between a portable and a whole-house generator?

A: A portable generator is a stand-alone unit that can be moved from place to place. It typically powers a limited number of appliances. A whole-house generator is permanently installed and automatically provides power to your entire home during an outage.

Q: Can I use a generator for my furnace if I have a heat pump?

A: Yes, you can use a generator for a heat pump. However, heat pumps typically require less wattage than furnaces, so a smaller generator might be sufficient. Consult your heat pump’s manual for specific wattage requirements.

Q: What are some tips for extending generator fuel life?

A: To maximize fuel efficiency, avoid running multiple high-wattage appliances simultaneously. Also, ensure your generator is properly maintained and running at optimal efficiency.