What Ohms should I be reading

How do I know what resistance this igniter should be

This chart is gonna help answer the question I get at almost every class, and it’s a chart I will put in the student books as well. What resistance reading should I get when I’m testing HSI’s?

When testing the resistance on HSI’s you want to make sure the unit is at room temperature. Don’t take a reading right after it’s been in the flame, or has been energized. As you can see by the chart, all the readings are done at room temperature.

The classic White Rogers 767A igniter should have no more than 75 Ohms of resistance at room temperature.

Check out the difference in resistance

You can also see that the readings are all over the map!

  1. The Honeywell Q3400A 24 volt igniter should see no more than 10 ohms.
  2. And the new Honeywell glowfly Universal Nitride igniter can seeĀ up to 90 ohms.
  3. The Carriers classic Norton should be no more than 90 ohms.
  4. But the Rheem’s Norton is good till 250 ohms!
  5. Then there is Lennox’s Sure Light 768A igniter that shouldn’t see more than 19 ohms.
So have a look at the chart. I’m sure there are others out there similar to this one, and perhaps with a little more information. If you are interested in downloading this chart, you can find it here …