Any HVAC Professionals In Here?

I need some help with my furnace, all I get on other forums is "pay a professional" lol.

 

Make and model # and symptoms might help.

 

Morning

Heil propane furnace.

It works fine for an hour or so, then one of the two (upper one) Flame Rollout Senors trips. So I reset it, works for another hour or so, trips.

The sensor that kept tripping I replaced, keeps happening.

I do NOT see any evidence of flame rollout as in nothing is dark, burned, singed.
I watch the two flame jets and they seem to work perfectly fine.
As far as I can see inside I dont see any blockage.
There is a little black soot lying around on a metal bar underneath the ignitor.

In my ignorance Im thinking if it works for an hour or so there isn't a blockage? I didnt see any blockage?

Advice please?

Thanks in advance!

 

Does it run for an hour straight? It shouldn't take that long to reach set point and cycle off.
What is the ambient temp in the house and what is the discharge temp?

 

For example, when I get home today it will be about 62 degrees at the thermostat. Ill turn it on. About an hour later the house might be say 68 then it just blows cold. Ill go downstairs and it will blink 7 times stating the switch was tripped. Ill open the case, reset it, close the case, and turn it on again. It will run for about an hour, then again trip.

 

Odd that it only goes up 6f in an hour. Are all the vents open? Filter clean?
Take a pic of the data plate and post it.

 

The filter is only about 2 weeks old - something that makes it take longer is that I have dual zone with a huge open foyer and the upstairs heat is not always on to equalize so some of the heat just goes upstairs. Data plate?

 

Kinda wonder if that Stat. doesn't have somethin' to do with it. Yeah, CurtB, 6F is pretty slow.

 

Something like the sticker in your truck door jamb. Like this

 

ok will do around 3pm when Im home thanks.

 

Data plate is on the inside of the unit, bottom or side, you will see it. It will look similar to what Bill posted.
I'm pretty sure this is all airflow related, and I think it has to do with the dual zone controls. I know next to nothing about them other than the few I've dealt with were a PITA.

 

It isnt dual zone, I have a furnace in the attic for the second floor. The one acting up is in the basement for the first floor. I also have a borescope Ill be using the look around. I wish it was easy to access the heat exchanger but apparently it is not!

 

Now you tell me lol. Do you have a probe type digital thermometer? The air temp entering the furnace, and the temp leaving the furnace will show the temperature rise. Data plate will show max temp rise. I'll bet it's over limit. And the high temp limit switch should cut out before a rollout switch.
Again, are all the vents open on the 1st floor?

 

No, I know for sure the vent in the 1st floor next to the garage door is closed, Ill have to see if any others are closed/blocked. Would this make a difference? What does it mean if it's "over limit" that means it's getting too hot?

 

If too many vents are closed, the furnace can't move air freely. The furnace overheats and shuts down by the high limit switch, or in your case the rollout switch. Open all the vents and see what happens.
Temp rise is the temp difference between the air entering and the air leaving the furnace. It will be listed on the data plate.

 

Awesome, thanks, I will get back to you this afternoon.

 

I think I've found the problem. The metal tubes, they look like the flamethrowers, spit out the fire. Well, it looks like the fire is coming out through the sides on the business end and hitting the metal on the OUTSIDE of the tube that goes into the heat exchange. Sure enough, I looked at the "good" furnace upstairs (exact same) and the flame went 100% into the heat exchanger.

 

I think this is the replacement part:
https://www.supplyhouse.com/Heil-Qu...pUKr70W9700Db1cpQduGDFx0sswaZVXBoCbqoQAvD_BwE

 

Update: I swapped the tubes from the working upstairs one (which looked great) to the downstairs one and the flame did not shoot out the side like the old one onto the metal. Time will tell if it works. I cleaned them both good with a copper brush, the old one was very clogged.

EDIT: Didnt make a difference.

Ran it with the door off for 30ish minutes, ran.
Closed the door, 5 minutes later, turned off. I felt the tripped rollout sensor and it was very hot. I was watching the flame the entire time and it never "rolled out" but I believe the heat is traveling from across the metal to heat it up from the heat exchange inlet.

 

That's a lot of yellow flame on that burner which causes more sooting (lazy flame). The flame should be about 1.5 to 2 inches long and 90 percent blue for the length of the flame.
I am not a hvac guy, but I work with a lot of gas appliances.