Do I Need a New Furnace If I’m Switching to a Heat Pump?

Sep 4, 2025 | Heat Pumps

Many homeowners upgrading to a heat pump wonder the same thing: “What happens to my furnace?” Some assume they have to remove it entirely, while others think they can just keep it as backup.

The truth depends on your home, your comfort preferences, and your long-term energy goals. In Northern California, where winters are mild, the answer often leans toward retiring the furnace. But there are times when keeping it makes sense.

This guide explains the differences, pros and cons, and how to decide whether you should keep, replace, or remove your furnace when installing a heat pump.

How a heat pump replaces a furnace

A heat pump works differently from a gas furnace. Instead of burning fuel to create heat, it uses electricity to move heat from one place to another. In the winter, it extracts heat from the outdoor air and delivers it inside. In summer, it reverses direction to cool your home—working like an air conditioner.

That means one system provides both heating and cooling. For most Northern California homes, that makes a heat pump capable of fully replacing a furnace and air conditioner.

Modern air-source heat pumps can heat efficiently even when outdoor temperatures dip below freezing. They’re quieter, cleaner, and often cheaper to run than older gas furnaces.

When keeping your furnace makes sense

Keeping your existing furnace can make sense in certain cases, especially if you want a dual-fuel system. A dual-fuel setup uses both a heat pump and a furnace together. The heat pump runs most of the year, and the furnace only activates when outdoor temperatures drop too low for optimal efficiency.

That hybrid approach is useful if:

• You live in an area that occasionally drops into the 30s or below.

• Your current furnace is fairly new (under 10 years old).

• You want the reassurance of having a backup heat source.

• You prefer to transition gradually instead of going fully electric.

For example, homeowners in higher elevations of Sonoma or Napa counties sometimes keep their furnaces for peace of mind. During rare cold snaps, the furnace can kick in automatically, controlled by a smart thermostat or zoning system.

This setup also helps if your electrical panel doesn’t yet have capacity for a fully electric system, since the furnace can share some heating demand until future upgrades.

When it’s better to replace your furnace entirely

In many cases, removing the furnace is the best long-term move.

If your furnace is more than 15 years old or showing its age with frequent repairs, it’s often smarter to replace it when switching to a heat pump. Combining both projects saves labor costs and ensures your ductwork and electrical are optimized for one system.

Reasons to replace instead of keeping it:

• Efficiency: Gas furnaces lose 20–30% of energy through exhaust. Heat pumps deliver up to 300% efficiency (producing three times more energy than they consume).

• Maintenance: One system is easier and cheaper to maintain than two.

• Incentives: Many California HVAC rebates and federal tax credits require full electrification. You’ll qualify for more rebates by removing gas equipment.

• Space savings: Eliminating the furnace frees up space for storage or upgraded air filtration.

• Cleaner air: No combustion means no carbon monoxide risk, pilot lights, or fuel exhaust.

If you’re aiming for an all-electric home, removing your furnace is the simplest path. It future-proofs your HVAC system and aligns with California’s ongoing push toward low-emission homes.

Comparing the two approaches

North HVAC Services can evaluate your setup and show how both options would perform in your home. Call (415) 845-6910 to schedule a heat pump consultation with one of their local technicians.

Factors to consider before deciding

There’s no one-size-fits-all answer. Your decision depends on how your home is built, your comfort preferences, and your energy priorities.

Here’s what to evaluate before deciding:

• Climate: Homes in coastal or inland regions (like Petaluma, Santa Rosa, or Novato) rarely need gas backup. Mountain areas might.

• Age and efficiency: If your furnace is nearing end-of-life, replacing it now is more cost-effective than maintaining it for a few more years.

• Ductwork: Both systems must share the same ducts. If your ducts are undersized or leaking, replacing both systems ensures proper airflow.

• Electrical capacity: Full heat pump conversions sometimes require an electrical panel upgrade.

• Rebate eligibility: Incentives may not apply if you keep gas equipment.

For example, the Energy Efficient Home Improvement Credit provides 30% back (up to $2,000) for qualifying heat pump installations through 2025—but only for all-electric systems.

How dual-fuel systems work

If you decide to keep your furnace, you’ll likely install a dual-fuel system. This hybrid setup lets your thermostat decide which heat source to use based on temperature.

Here’s how it works:

• On mild days, the heat pump handles all heating efficiently.

• When outdoor temperatures drop below a set point (usually around 35°F), the thermostat switches to the furnace.

• Once temperatures rise again, the system reverts to heat pump mode.

This automatic switching maximizes efficiency while maintaining comfort. However, it adds cost and complexity, since both units need annual service and compatible controls.

Why California homeowners are going all-electric

California is rapidly transitioning toward electrification. Homeowners who switch from gas furnaces to heat pumps can qualify for rebates from PG&E and regional programs like BayREN.

Heat pumps are now designed for California’s climate—delivering steady warmth even when it’s 30°F outside. Many models operate quietly, integrate with smart thermostats, and use R-410A or R-454B refrigerants that are more environmentally friendly than older systems.

All-electric homes also eliminate the risk of gas leaks, reduce greenhouse emissions, and simplify future upgrades like solar integration or battery storage.

How to prepare for a furnace-free upgrade

If you’re leaning toward full replacement, take these steps before installation:

1. Schedule a professional load calculation. This determines the correct system size for your home’s heating and cooling needs.

2. Inspect your ducts. Leaky or undersized ductwork can undermine efficiency.

3. Check your electrical panel. Some homes need a breaker upgrade to handle heat pump power requirements.

4. Compare rebate options. Programs like BayREN Home+ and Federal Energy Credits can significantly reduce your installation cost.

When you work with North HVAC Services, their technicians handle this assessment for you—ensuring your system is properly sized, installed, and eligible for available incentives.

The financial and comfort payoff

New heat pumps can reduce heating and cooling costs by 20–50% compared to older systems. Combined with available tax credits and California rebates, homeowners can often recoup part of their investment in just a few years.

You’ll also gain:

• Consistent temperatures throughout the home

• Lower noise levels compared to older gas systems

• Cleaner indoor air with better filtration options

• Remote control and monitoring through smart thermostats

For many homeowners, comfort improves immediately after switching—and energy bills drop noticeably.

Making the right choice for your home

If your furnace is still fairly new and you want backup heating, keeping it temporarily is fine. But if it’s old, inefficient, or limiting your rebate options, replacing it is usually the better decision.

North HVAC Services helps homeowners across Sonoma, Marin, and Napa counties compare system options, evaluate long-term savings, and choose the best setup for comfort and cost efficiency. To find out which path fits your home, call (415) 845-6910 and schedule a personalized consultation with a licensed HVAC expert.