Harman Control Board Fuse 5 Amp, 3-20-49446

SKU 3-20-49446
MPN 3-20-49446
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This 5 Amp, 20mm, control board fuse is located on the backside of your Harman Stove Circuit board. Most units made after 2013, Revisions E and up, use this shorter fuse.

Most stoves and inserts made prior to 2013, with auto ignition, Revisions E and under, will use a 30mm 6 Amp fuse, 3-20-49447, those without an igniter will use this fuse, also use a 5 AMP fuse but it is the larger 30mm size, part 1-00-05237

Before ordering a fuse, unplug your unit, remove your fuse from your controller and measure the length.

  • All 30mm fuses (1.1811") in stoves without an igniter are 5 Amp.
  • All 30mm fuses (1.1811") in stoves with an igniter are 6 Amp.
  • All 20mm fuses (0.787402") are 5 Amps.
  • Sometimes controllers have been replaced since your stove was installed, your actual fuse type may be different the controller was updated.

Check out the TROUBLESHOOTING tab regarding fuses.

fuse markings chart


Replacement For Part Number:
  • 3-20-49446

Technical Specs

Volts <250V
Length 20mm


If you keep blowing fuses at start-up, here is a simple way to troubleshoot the problem to see which component is causing the short.

NOTE 1: Before you get too involved in troubleshooting every component when you have the controller out of the stove to access the fuse, look at the controller very carefully on both sides for signs of a short circuit on the board itself. It's usually pretty obvious. If you see any signs of carbon, which looks like a fire or hot spot on the board, or if the controller smells like an "electrical" burning smell...just replace the controller and start from there. This step is especially important if you recently had a power outage and your stove wasn't plugged into a surge protector.

  1. You are going to need at the most, 4 fuses to troubleshoot the problem without using a multi-meter. Unplug the unit and place a new fuse in the controller. Make sure the controller is not touching any metal if it is not mounted in the stove. By process of elimination, we will get to the root of the problem. Make sure that the mode selection switch on your stove is set to "OFF" for this whole process.
  2. Both the combustion motor circuit and the ignition/feed circuit are energized for roughly 2 seconds when the stove or insert is plugged in. If you do not have an igniter and your fuse is blowing the moment you plug in your stove, replace the combustion blower.
  3. If you have an igniter, we need to isolate each circuit from the controller. On the back of your stove or insert, find the pressure switch. There will be two light blue wires that connect into a single terminal on one side and a single white wire that connects on the other side. Remove the white wire from the pressure switch.
  4. Plugin your unit. If you blow the fuse at that moment, replace the combustion blower.
  5. If the combustion blower comes on for 2 seconds and then turns off and you do not blow the fuse, your problem is most likely a shorted igniter or a bare wire for the igniter inside of the burn pot.
  6. Unplug the unit. Find the light blue and yellow wires that pass through the rear of the unit for the igniter. Cut the zip tie that cinches up the extra length of these wires and then push some of that length into the back of the stove towards the igniter.
  7. Remove the burnpot cover plate, release the igniter and cradle and gently pull the igniter out of the burnpot about 6" until the wire disconnects are visible. Inspect the igniter wires for bare spots. Check the igniter for warping. These are signs of a short. Unplug the igniter from the yellow and blue wires.
  8. Reconnect the white wire to the pressure switch
  9. Plug in the unit. The combustion blower should come on for 2 seconds. Turn on the stove in either mode. If the fuse does not blow, replace the igniter. When installing the igniter make sure that the wires are not pinched under the cradle when it is reinstalled. If the fuse did blow, continue...
  10. Unplug the unit, reinstall the igniter, pull the extra length of yellow and blue back towards the cooler part of the stove in the rear, tie up the loose ends. Make sure the pressure switch wires are reconnected, Plug in the stove. If you blow a fuse you either pinched the igniter wires or you have a short somewhere in your wiring harness. If you did not blow the fuse, continue...
  11. Unplug your stove. In the wiring harness, find the black wire. This is the feed motor power wire. Disconnect it where it meets the black wire of the auger motor. Plugin your stove. Turn your "Feed Trim" knob to test. If you blew a fuse, your distribution blower motor is shorting out, replace it. If you didn't blow the fuse, continue...
  12. Turn your "Feed Trim" off of the test area. Unplug the stove. Reconnect the black auger motor wires. Plug your stove back in and try and start it in "Room Temp" mode and make sure the igniter toggle switch is in the Auto position. If it blows a fuse, replace the auger feed motor.
  13. If you got to step 12 and you didn't blow a fuse, your stove should be operating normally.
  14. If you blew a fuse again, retrace your steps. If you are at a loss, you can always test the individual components of your stove for Ohms resistance but you may have to study some to understand how to do this.


  1. It doesn't happen often but it has happened to me a few times where there is actually more than one component shorting out so it's okay to feel discouraged and confused...you may just have to keep following these steps until you can get to step 12 and have the stove running again.
  2. If your fuse blows at or around the same time as the distribution/ convection blower turns on, that motor may be the cause but not necessarily. Fuses have an AMP rating that allows the fuse to blow when the AMP rating is exceeded. This is the total draw of amps used by all components for all of the circuits that are closed at any given time while the stove or insert is being used. It's not uncommon for stove components, especially motors, to exceed their AMP rating as they age so it's entirely possible for components to "still work" but also contribute to fuses blowing. When this happens, it's usually never at startup. This problem usually happens at random and the stove will need to have been running for a period of time. As motors age, they become less conductive, which causes them to heat up, which causes them to draw more power to do the same work. Fuse AMP ratings allow for some AMP draw tolerance of aging components. If any single components OR if the sum of two or more aging components draws too many AMPS, the fuse will blow. The only way to test this scenario is with a meter and you need to test the components when they are hot. At startup components usually test within limits but fall out of spec the longer they are in use. To avoid this situation, or if you are pulling your hair out trying to figure out the problem, consider replacing your motor components at least every 8-10 years.
  3. Typically, at startup, any stove or insert is only using a total of 3 circuits; the combustion motor for combustion air, the auger or feed motor for fuel, and the igniter to create heat to initiate combustion. If during start-up, if the fuse AMP limit is exceeded, the fuse will blow. In this scenario, the distribution of convection blower can be ruled out as a potential problem because that component hasn't "turned on" yet, as we are waiting for the stove to detect "proof of fire". Once "proof of fire" is established, the ignition circuit is turned off or "opened" to allow the distribution/ convection blower to be powered up without exceeding the AMP threshold. For example; the combustion motor is about 1AMP, the feed motor is about 1AMP (when it's on) and the igniter is about 3AMPS, for a total draw of 5 AMPS during ignition. With a 6 AMP fuse, there would be some leg-room for any component to be slightly out of spec due to wear and tear and the stove could still operate within the limits.
  4. Igniters typically do not ever "over-draw" on AMPS at any time and still continue to work. They either work correctly, within spec, or they over AMP and short out.


Unfortunately, sometimes products do not work like they are supposed to. We offer a 90 day warranty on manufacturer defects. Some manufacturers make this a very simple and easy process unfortunately others do not. Items must be used in accordance with the manufacturers guidelines to qualify for warranty replacement. Please be advised that warranty claims for these parts may take up to 4 weeks for processing, and customers must cover shipping.

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