FAQ

furnace is overheating (the furnace has been known to glow orange when this occurs)

Replace the solid-state relay—Part Number NC-2510

The door seems loose when I open and close it and/or the door is not latching correctly

If the door is loose, you will need to realign the door and tighten the hinges. This can be accomplished by closing the door, pulling out on the hinges until the door sits flat against the furnace, and tightening the hinges down

Low lift test (lift should be between -3 and -8)

Check the blower fan is running and relatively quiet.  If the fan needs to be replaced, PN NC-1500 (1087/1275) or NC-1520 (859/945) Clean the upper section of the NCAT furnace as described in the maintenance section Verify the door is closing correctly.  See “Door Loose” section Check the filter temperature as described in the “Long Burns” section Verify there are no obstructions in the exhaust tube

The furnace is taking a long time to heat up

Check the heating elements.  They are the left, right, top, and bottom walls of the chamber.  If or more of them is cool, while the others are warm, they will need to be replaced.  As there are multiple variations, you will want to check the website and/or call HMA Lab Supply to ensure you order the correct part.  Please verify your model and SN as outlined in the “General Information” section prior to ordering If the left and the right heating elements are not heating, you will want to ensure your furnace is not in the low-power configuration.  This is an older configuration that was designed for 20A use and disables the left and right elements.  To check the configuration, unplug the furnace from AC power, open the back panel of the furnace and check the lower left-hand corner.  There should be a wire joining the two connectors there.  If it is either not present or connected to itself, then the furnace is in the low-power configuration.

The furnace is not heating

If the temperature is below 50F (10C), take a match/cigarette lighter, and apply the flame directly to the chamber thermocouple for 15-30 seconds.  Once the red display starts to change, the furnace should begin heating when you close the door Occasionally, when the furnace has been idle for several days, the red display is a little slow to respond.  Close the door for 30 seconds, then feel the left, right, top, and bottom walls of the chamber.  They should begin to feel warm to the touch. Check the door interlock.  There is a tab on the lower side of the door, near the hinges.  It should go into a slot on the furnace itself.  Verify that the tab is going in correctly; sometimes the tab will catch and get bent.

I came in this morning, and the furnace displays ‘INAC’ on the screen

This is a safety feature, often used alongside the startup timer. It only triggers if the furnace is idle for over 4 hours, and it shuts the heating elements off. To reactivate it, just hit ‘enter’ on the keypad and the furnace will begin operating as normal