Do Furnaces Have Fuses?
What this costs
| Option | Job | Low | High |
|---|---|---|---|
| Replace | Furnace Replacement | $2,950 | $8,350 |
Two different protections
Not every model looks like this. Check the manual for your model and the label inside your furnace.
- At your panel: Rheem's manual says the furnace's 115-volt power must come from a dedicated circuit with the correct fuse or breaker.
- On the furnace: the same manual's wiring diagram shows a 3-amp fuse on the integrated control board, next to the low-voltage thermostat connections.
What you can check
Check your panel first. If the furnace's breaker tripped, CPSC says to find out why, and to get a qualified electrician if it keeps happening. Also look for a furnace power switch, often on or near the unit, that may have been turned off. Don't open the furnace cabinet to look for the board fuse unless you know the model and are comfortable. Rheem's instructions warn that the work is for qualified people and that not following them could cause a fire or explosion.
Why a new fuse isn't always the fix
A fuse blows to protect something. CPSC's older guide warns against using a higher ampere fuse than the circuit calls for, since that lets wiring overload. That guide is about house panels, and we apply it here by analogy. We recommend a technician find the cause of the blown fuse.
If you smell gas
Leave the house right away and call your utility or 911 from outside. Carrier says not to troubleshoot a suspected gas leak yourself.
Furnace Won't Turn On? Safe Checks Before You Call
Common questions
Why would my furnace blow a fuse?
What size fuse does my furnace use?
Related questions
- Are GFCI Outlets Required in a Garage?
- Can a Breaker Go Bad Without Tripping?
- Can a Light Switch Cause a Breaker to Trip?
- Can a Roof Leak Be Fixed From the Inside?
- Can a Water Heater Leak Carbon Monoxide?
- Can Breakers Trip for No Reason?
- Can Garage Door Springs Kill You?
- Can GFCI Outlets Go Bad?
Last verified 2026-11-04
- Rheem: *RA series gas furnace installation instructions — Wiring diagram shows a 3 amp fuse on the control board; 115-volt dedicated branch circuit with correct fuse or breaker; disconnect within sight; qualified individuals.
- U.S. Consumer Product Safety Commission: Home Wiring Hazards publication 518 (undated older guide) — Don't put in a higher ampere fuse; a fuse that blows repeatedly needs a qualified electrician.
- Carrier: Furnace not turning on — Safety warnings; when to call.
- Public Service Commission of Wisconsin: Natural gas consumer safety — If you smell gas, leave immediately and call the gas utility's emergency number or 911 from a safe distance outdoors; odor described as rotten eggs, sulfur or garlic.
General information, not professional advice. Conditions, codes and prices vary. Turn off power, gas or water before any work, and hire a licensed professional when in doubt. Cost figures are our estimates, not quotes.