image of a technician pressing a power switch, there are displays showing all 8s

How To Pass a Lift Test on your NCAT

The lift test is a powerful tool that you can use to keep your NCAT’s burn time short. It can tell you if you have faulty components and can even impact your results. Our technicians use this test to determine what they need to do when they start service, and often it’s the first thing we do when we refurbish units. In this article we will cover the lift check and why it’s the most important diagnostic tool for your NCAT.

What is a lift test?

The lift test is a feature on an NCAT ignition furnace that shows you the amount of air moving through your unit. The air, which comes in from the bottom, hits the hearth plate and then moves up and out through the top of the chamber. In the balance indicator screen, we get a negative number. The highest negative value is your NCAT’s lift.

How to do a lift test

To find out what your lift number is you first need to make sure that your unit is off and cold. If your unit is hot, you won’t get an accurate number. Once you have a cold NCAT, perform the following steps:

  1. Open the furnace door
    • We do this to make sure that the furnace doesn’t heat prematurely.
  2. Turn the unit on by flipping the green power switch
  3. Let the scale finish its countdown and zero out
  4. Shut the door
  5. Re zero the scale if necessary
  6. Press the start button on the keypad
  7. Look for the highest negative value on the balance indicator screen
    • This is your lift number.

What should my lift number be?

It really depends on what series your NCAT is. If you don’t know what series you have, check out this article to find out.

If you have a newer series (1087 or 1275) then your ideal draft is between -4 to -7. Anything higher than that and your furnace will struggle to maintain its temperature, while anything lower will result in incomplete burns and a longer burn time. Essentially, more air equals more ignition.

If you have an older series (859 or 945) then your ideal draft is between -4 to -6. It is very important to make sure that your lift never goes above -6 as your furnace will not be able to get back up to temperature.

Why should it be done?

The lift test can tell us a lot about the unit. It can tell us if it needs to be cleaned. It can tell us if the blower motor is functioning properly. It can even tell us if there are components that need to be replaced. In short, the lift test is the single most important diagnostic tool in our arsenal. By knowing your number, you can save yourself from hours of painstaking work.

What to do if your NCAT doesn’t pass

If your furnace is below the ideal draft, you are extending your burn times past 40 minutes. There may be many reasons why the number would be low, but the key areas to focus on are how dirty the top of your furnace is, and if your blower motor is functioning.

Cleaning The Top

To clean the top of your unit you will need to take off the top cover and take off the metal box that sits inside of the top. PLEASE DO NOT DO THIS WHEN THE UNIT IS HOTThe tools you will need:

  • A Phillips Head screwdriver
  • An 11/32 Nut Driver or wrench
  • Shop Vac (a Bag is highly recommended to limit mess)
  • Cleaning Wipes (We use Tub O Towels)

The first thing you need to do is remove the back metal plate (if you have it) that secures the top to the unit. Then you’ll slide the top off and set that aside.

Next, you will need to disconnect the blower motor wiring harness. While you’re here you should oil your blower motor too.

Then, you will use your nut driver to loosen the 4 nuts holding down the metal box and slide back the metal plate covers.

Finally, slide back the metal plates and lift the metal box off of the unit and clean the inside. You will get dirty.

Once you have cleaned the metal box and put everything back together, you will need to run a new lift test and see where your number is.

What to do if your NCAT is still not passing

If you have gone through all the steps above and still have an incorrect lift number then it’s time to call in the experts.

804.893.4076 or email [email protected]

Gordon Technical technicians are trained to service your NCAT by a factory trained master technician. They know every single component by heart and know how they all work together. How do we know? They aren’t able to service equipment on their own until they pass a test.

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