When to check for a cracked HX

[ATLtech]

I am curious as to when everyone begins to check for a cracked heat exchanger and the extent to which they go.
Normally I visually check the burners before and after the blower kicks on for flame movement. I also heat up the furnace, unplug the inducer, keep the blower motor running and stick a log lighter into the HX to check for flame movement.
I have several different methods to find cracks in the HX if suspected, but the suspicion is what I have a problem with. On every service call, do you perform an intense check (pulling blower to inspect, spraying HX, etc) even if there are no red flags (such as flame movement)? Or do you need "probable cause" to start the process?

Thanks

[Gross]

Every call, everytime. Period.

Visual inspection a must :/

[kyjourneyman]

I will always do a visual everytime. But on furnaces over 20yrs. I will break out the camera or do a smoke test.

[John Markl]

Copious amounts of rust in or on the burners is a red flag. Visual observation of the flame movement is also key.

Typically, a HX under 20 years old is not likely to have failed....unless it's in a gas pack.

In gas packs, if you're experiencing roll-outs tripping, you can almost bet that you have a bad HX.

:.02:

[ductductgoose]

Flame inspection is critical however some units will roll out if the cover is supposed to be on when the flame is present. So just because you see flames moving don't diagnose it bad without proper inspection cause you'll look the fool if someone who knows comes behind you for a second opinion

[John Markl]

Flame inspection is critical however some units will roll out if the cover is supposed to be on when the flame is present. So just because you see flames moving don't diagnose it bad without proper inspection cause you'll look the fool if someone who knows comes behind you for a second opinion

You mean, like a RUUD gaspack? :whistle:

[chuckcrj]

Typically, a HX under 20 years old is not likely to have failed....unless it's in a gas pack.

Maybe down south....

The majority of failed furnace hx I see are less than 20 years old. I have replaced 4 this year that were under 10 years old.

[John Markl]

Maybe down south....

The majority of failed furnace hx I see are less than 20 years old. I have replaced 4 this year that were under 10 years old.

If they're gone in less than 10 years, there's something else wrong.....the bad HX is just the symptom...

[chuckcrj]

If they're gone in less than 10 years, there's something else wrong.....the bad HX is just the symptom...

Yep, all 4 were a combination of underfired, and no post purge on the inducer. Tail end of primary rusted through.

We have a 9 to 10 month heating season which equals a lot of young furnaces dead.

[ductductgoose]

If they're gone in less than 10 years, there's something else wrong.....the bad HX is just the symptom...

YEPPERS like undersized ductductgoose work :whistle:

[chuckcrj]

Yep, all 4 were a combination of underfired, and no post purge on the inducer. Tail end of primary rusted through.

We have a 9 to 10 month heating season which equals a lot of young furnaces dead.

Both manufacturer defects, I should add, and very common ones at that.

[billygoat22]

If longer than a year since last call, then I check. unless something looks off.

[SuperDave89]

to many companys swap out furnaces they just put it in real quick and walk away. They dont go through proper set ups like checking gas pressure, temp rise or proper duct work sizing. To many newer furnaces are being oversized which is causing short cycling and these cheaper made heat exchangers can not last.