Any furnace guru's?

[Ron H]

Guy jumps out of a plane and begins falling frantically pulling at his rip cord. Half way down he passes a guy going up and says “Do you know anything about parachutes?”
The guy responds “No, do you happen to know anything about gas furnaces?”

Lol, that's one reason I never had the gumption to jump out of a plane, train, or automobile...did enough other chit though to cause personal injuries (to me).

 

[Demonic]

The furnace was designed without a filter..

No. Whoever did the return duct failed to fab a filter rack.

 

[bm02tj]

Unit heaters have no duct work and never a filter

 

[Ron H]

Followed install instructions including venting options, required pitch, etc. No mention of a filter install..

 

[Burnout68]

Sorry didn’t realize it was a unit heater no filter needed different than a residential furnace which is what I was thinking
So now I’m guessing you have a loose terminal on one of the limits check those may have to crimp down on the terminal a little to make it fit tighter on the spade

 

[Ron H]

My apologies gents; I should have included a better description what unit I have that my earlier photos wouldn't have revealed such as a photo showing the entire unit..

 

[Burnout68]

No worries

 

[Burnout68]

Different type of fan also than what I was thinking earlier
So should be good they don’t get the build up like the other squirrel cage blowers do
Your type(prop fan) can be wiped easily or blown off like you did

 

[Moms68]

Thanks guys; sail switch or fan inducer I'm unaware of. Does this show up in my top photo of the guts, my OP? Will check for cracks on exchanger - my guess is if this is bad it's time for a new furnace huh? Had one put in the house furnace and was pricy.

in the photo below, see the proving switch (round silver) and the red hose going to it. There should be 2 wires going to it, which should have low voltage on both terminals when the unit starts. Is that red hose kinked at the top?

(

 

[Ron H]

in the photo below, see the proving switch (round silver) and the red hose going to it. There should be 2 wires going to it, which should have low voltage on both terminals when the unit starts. Is that red hose kinked at the top?

View attachment 1218321 (

Still out in garage, checked the hose seeing your post...its good, no kinking or collapse.

 

[Burnout68]

Check for loose terminals on the limit switches I would follow that whole circuit follow those wires to the board and make sure you have good/tight connections since that seems to be where you getting the error code for the limit switches and the symptoms it’s having
Then when tap it works, either a limit resetting or loose wire/terminal I’m thinking

 

[Demonic]

Sorry didn’t realize it was a unit heater no filter needed

Yeah, a couple of us missed that. All these forum guesses aside, mine included - you need to logically troubleshoot with a multimeter.

 

[hunt2elk]

Another thing to check is for a poor connection on the molex connector on the circuit board. Pull the plug and check their condition. I sometimes will spread the terminals a bit and after it is back together, take a pick and make sure each terminal is fully seated. Sure sounds like you have a problem in the high limit switch circuit though. When you replaced that switch, did you shine a flashlight in the hole just to be sure there isn't a crack in the exchanger where the switch sets? That would cause it to open up as well. But, it should do it every time if that was the problem.

 

[Moms68]

Try removing this cover. May be able to access the screws holding the flame sensor or be able to clean it.

 

[bm02tj]

no will not give access

 

[Burnout68]

Did you ever figure out the problem?

 

[Ron H]

Did you ever figure out the problem?

Well - my next move is still taking out the bracketing to get to the dang flame sensor - but - the furnace still plugs away giving some heat sometimes nicely and then not so much...but some heat...and but it's been friggin cold enough here not wanting to do this if I encounter a hassle that will have me with no heat for a day or longer. Right now far as I can tell, a root cause of the trip outs aim to the sensor. Hope this is what it is. My go-to furnace outfit I've used won't service Lennox so have it on the list to find a place that does. Appreciate you asking and will update hopefully with a success story.

 

[bm02tj]

It is not hard to do just do as I said in my earlier post
Yes Lennox did build with some stupid ideas

 

[Burnout68]

Well - my next move is still taking out the bracketing to get to the dang flame sensor - but - the furnace still plugs away giving some heat sometimes nicely and then not so much...but some heat...and but it's been friggin cold enough here not wanting to do this if I encounter a hassle that will have me with no heat for a day or longer. Right now far as I can tell, a root cause of the trip outs aim to the sensor. Hope this is what it is. My go-to furnace outfit I've used won't service Lennox so have it on the list to find a place that does. Appreciate you asking and will update hopefully with a success story.

Don’t sound like a flame sensor problem if burner stays on longer than 3seconds
But if can’t take apart yourself
If can reach with a wire brush/sand paper and just brush as good as can
It’s just a metal rod so basically just cleaning it
Crazy nobody wants to work on it because it’s Lennox
Every company I’ve worked for worked on anything heating & cooling

 

[Burnout68]

Also did you have this problem before you replaced the fan?