New Series, Old Series, Which NCAT Do I Have?

If you have ever called in for maintenance, you’ve been asked this question. Do you know which series you have? It’s your typical deer in a headlights situation. There’s always an audible silence before the caller ends up saying, “no” and “how can I find out”?

Today, we are going to tell you the difference between a new series NCAT (1087 and 1275) and an old series NCAT (859 and 945).

How to tell which series furnace you have

  • The Door
  • The Chamber
  • The Blower Motor Wiring Harness
Old Series NCAT
Old Series NCAT Furnace

The Door

The easiest way to tell from a distance if your NCAT is an old or new series is to look at the door.

In old series furnaces, the top of the door will align perfectly with the top cover. Whereas in new series furnaces the top of the door sits below the top cover.

This is due to the Newer series furnaces having a separate area for the coarse ceramic filter and afterburner heating element. Instead of redesigning the door, Thermolyne decided to increase the space above the chamber as the new afterburner would also need more insulation and a new way to seat a thermocouple.

refurished NCAT
New Series NCAT Furnace

The Chamber

What series NCAT do you have? if yours looks like this than you have a newer series furnace
New series NCATs look like this with no metal basket in the chamber.

Let’s say that you’ve walked up to the unit and still aren’t sure which series you have. Your next option is to open the door and look inside the chamber. Do NOT do this while the unit is on or operating. The NCAT is hot and at those temperatures, you are likely to start a fire.

When looking inside the chamber if you see a metal basket at the top of the chamber you have an old series furnace, and if you don’t, you have a new series furnace.

Why is it this way?

When Barnstead first created the NCAT they built the chamber so that all of the ignition and cleaning would happen there. This meant that in addition to heating elements, they had to create a space for coarse and fine ceramic filters to scrub the smoke before it hit the afterburner element. The fine coarse ceramic filter has since been discontinued

The chamber gets really hot during ignition and they knew that the filters had to sit in something so they went with metal. And of course, because there is a lot of oxygen in the chamber steel would rust to oblivion. Therefore they went with stainless steel.

Blower Motor Wiring Harness

Ok, ok. So you’ve looked at the door and the chamber and you still aren’t sure what series you have. Your next option before calling in a technician is to take the top cover off and look at the blower motor. Again, DO NOT DO THIS WHEN THE UNIT IS STILL HOT. The top cover is very hot and can severely burn you. Seriously, don’t.

This method is a little less reliable than the two others, but you need to look at the wiring harness coming off of the blower motor. If you see an orange sheath around them, you have an older series blower motor and may have an older furnace.

This was done because the wires coming out of the blower motor sit directly on the metal. Obviously, when the metal gets hot, the wires would get hot and melt. Thermolyne didn’t want to make a single-use blower motor so they designed a heat-insulating sleeve to protect the wires.

Having said that, please don’t rely on this method. A lot of times, other companies macgyver a solution from old parts and don’t understand why this isn’t a good idea.

What if I still don’t know

If you are still unsure or want to be 100% without a doubt what series your unit is, send us an email with a picture of your unit to One of our technicians will be able to tell you what series you have and can help you out if you’re having trouble with your unit.