Furnace question
 

I hired a heating and air company to do a service on a furnace in one of my rental units in Reno. His diagnoses was that the furnace is in good condition but that the igniter was showing signs of age. My experience with igniters, although limited, is either they ignite or they don’t. Am I wrong? Can a technician tell by checking ohms? Should I just replace the igniter? So many questions.

I'm showing signs of age too. I still go to work every day.

Ignore. But maybe buy one online and have it ready.

Good idea.....I have replaced one before although not on this furnace. Not that difficult.

Some ignitors work like spark plugs, others like glow plugs.

If you have a hot surface ignitor (HSI) "showing age" can be some white residue on the ignitor. HSI's pretty much glow or they don't. If they don't, they REALLY need replaced. I consider them a maintenance item that should be replaced depending on age. Having a spare on hand can't hurt either.

I've had the ignitor go bad on my heater. Sometimes it would work and sometimes it wouldn't and many times it would click many times before lighting. So, I would say they can go bad or work poorly before completely going out.

What kind of igniter? Spark or hot surface? I had a lot of problems with the hot surface igniter on a Bryant. I think it was just bad design. The gas wasn't introduced to the heat properly or something. Never had a problem with a spark igniter.

Me too. Eventually it broke and didn’t ignite anymore. Cheap and easy to replace, nice to have a spare on hand.

The guy saw it cycle thru an ignition sequence without main flame occurring. Its not going to get better. You can see the difference with a new ignitor , they glow brighter

IPI (intermittent pilot ignition) or HSI (hot surface ignition)?

If it is an IPI, you can see if the ignitor is pitted and corroded from years of use. Flame signal will degrade after time.
HSI as mentioned will get whiteish as they age.

Both prove flame after ignition so their ability to prove safe combustion after ignition is as important as igniting the flame.

IPI ignitors clean with some emery cloth and the grounding rod too. Make sure that there is a good ground.

HSIs can be gently dusted with compressed air. They can be more fragile as they age. Visible cracks are a bad thing.

IPIs can be tested for micro amps as an input to the ignition board.

It’s a hot surface igniter. Technician said the ohm reading was telling him it’s going to fail. When? He couldn’t say. Don’t they all fail eventually?

Yes.

Some of them get brittle over time, such that fiddling with them will cause failure. Some have suggested getting a spare and having it ready, which makes sense. Or just replace it. And get a spare. And tape it to the furnace door.