The short answer
You likely need a new furnace if repairs keep recurring, the heat exchanger is damaged, or your home heats unevenly despite service. We inspect the full system, explain whether repair, a new gas furnace, or a heat pump fits your home, and quote only after seeing the job. Bay Area rules don't force you to replace a working furnace.
When a furnace stops keeping up, the decision is bigger than which model to buy. You need to know whether the old unit is worth fixing, what size a new one should be, and how current Bay Area rules affect your options. Prime Choice HVAC Repair Service installs furnaces for homeowners in San Jose and nearby cities. Every job starts with a look at the whole heating system, not just the unit in the closet, garage, or attic. Here's what to watch for, what we check, and how a visit works.
Signs It May Be Time for a New Furnace
Santa Clara Valley winters are mild and damp rather than harsh, so furnaces here often run fewer hours than they would in colder regions. That can hide problems for a long time. These are the signs that a furnace may be nearing the end of its useful life:
If you smell gas or your carbon monoxide alarm sounds, leave the house and call your gas utility or 911 from outside before doing anything else.
- The same part fails more than once, or repairs keep coming back each season
- Some rooms stay cold while others overheat, even with vents open
- The burner flame looks yellow or flickers instead of burning a steady blue
- Gas bills climb without any change in how you use the heat
- New noises such as banging at startup, rattling, squealing, or a blower that won't shut off
- A burning smell that lingers well past the first few days of the heating season
- Rust, cracks, or soot on the cabinet or around the vent pipe
- Replacement parts for your model are getting hard to find
What We Check Before Recommending Anything
A furnace that's the wrong size or connected to leaky ductwork won't perform well no matter how new it is. Before we suggest repair or replacement, our technician looks at:
Sizing deserves extra attention. An oversized furnace short-cycles, wears out faster, and causes temperature swings. An undersized one runs constantly on the coldest nights. We base our recommendation on your house, not on a rule of thumb or the size of the old unit.
- Heat exchanger condition, including cracks or corrosion that could let combustion gases escape
- Burners, igniter, flame sensor, and gas valve
- Blower motor, capacitor, and related components
- Venting and flue pipe for proper slope, clearance, and secure connections
- Ductwork for leaks, crushed runs, and disconnected sections, especially in attics and crawlspaces
- Filter size and the return air path
- Thermostat wiring and settings
- Your home's size, insulation, windows, and layout
Repair, Replace, or Switch to a Heat Pump
If the furnace is in reasonable shape and the problem is a single part, such as an igniter, flame sensor, or blower motor, repair is often the sensible choice, and we'll tell you so. Replacement makes more sense when the heat exchanger is damaged, when major components fail repeatedly, or when repair bills keep adding up on an aging unit.
Bay Area homeowners also have a third path to consider. Under Bay Area Air District Rule 9-4, natural gas furnaces manufactured from 2029 onward must meet a zero-NOx emission standard. In practice, that points homeowners toward heat pumps when replacing a furnace after that date. The rule does not require you to replace equipment that's working. It applies only when an existing furnace fails or is replaced.
That leaves you with several options today:
Each option has trade-offs involving electrical capacity, ductwork, and comfort. We walk through them with you so you can choose based on your home and how long you plan to stay.
- Replace a failing furnace with a new, more efficient gas furnace
- Install a heat pump that heats in winter and cools in summer, which can be especially useful in the hotter inland and southern parts of the valley
- Pair a heat pump with a gas furnace as a dual-fuel system
What Affects the Cost of a New Furnace
We quote every installation after seeing the home, because the details change the job. The main factors are:
On incentives: the federal Energy Efficient Home Improvement Credit (25C) covered qualifying heat pumps placed in service before December 31, 2025, and it isn't available for new installations after that date. BayREN and your local clean energy provider may offer heat pump and electrification incentives, but amounts and availability change by funding cycle. We confirm the current offer before including it in a quote.
- Equipment type: single-stage, two-stage, or variable-speed furnace, or a heat pump
- The efficiency rating of the unit
- The size your home needs
- Installation location, since attic, garage, closet, and crawlspace jobs differ in access and labor
- Duct sealing, repair, or replacement
- Venting changes, especially when moving to a high-efficiency condensing furnace
- Electrical panel work if you're switching to a heat pump
- Permits required by your city
- Thermostat upgrades or zoning
How a Furnace Installation Visit Works
We keep the process clear from the first visit to the final walkthrough:
A straightforward furnace swap can often be finished in a day. Jobs that involve ductwork, venting changes, or a heat pump conversion take longer, and we'll give you the expected timeline before work begins.
- Inspection and conversation: we check the current system and ask which rooms are uncomfortable, how you use your heat, and what matters most to you
- Recommendation and written quote: you get clear options, including repair when it makes sense
- Scheduling and permits: we handle the permit process with your city
- Installation: we protect your floors, remove the old unit, set the new equipment, connect gas or electrical, venting, and ductwork, then test the system
- Walkthrough: we show you how to change the filter, use the thermostat, and what to watch for going forward