Rollout Switch tripping on ICP Commercial

Hi guys-

I have an outdoor ac/furnace unit (ICP Commercial, model: PGF030K080A).
Got it 11 years ago.

3 weeks ago, the flame rollout switch started tripping. It would run for ~5-10m then trip. After resetting it several times, it kept working.

I had company come out for $95, they said the draft inducer motor was making noises and probably the cause - quoted me $760 to replace! I looked online, and part was $145 on amazon -- I got it shipped fast for $185, and installed it... was very simple.

A week later, happened again. Got another company out for $85... they did a candle-test to see if the heat exchanger could be cracked.... the guy saw it dance around a bit, so he said that must be it.

They couldn't give a quote yet, since it's xmas.... though i looked and found part is $850! I paid $2900 for the whole thing. I'm sure they'll quote me some crazy amount.... since this part doesn't seem that quick to swap.

Today it's happening again... i'm only praying it'll stop and won't happen in middle of night.

Anyone have suggestions of something else it could be? i'm not sure if to trust them... if they're like first company, it could be wrong analysis again. Is there a better way to be sure the heat exchanger is cracked for sure? To me, just seems odd that it works for a week with no issues.... then has a problem for a few hours... then ok again for a while.

Thanks,
ben

 

Symptoms of a cracked heat exchanger for starters is headaches and dizziness while the heat was running. You can also buy a carbon monoxide alarm and put it near a vent that blows hardest. If it goes off you have a cracked heat exchanger. You could look inside the exchangers to see if they look rusted. A flashlight helps. If rusted all the way, it's probably cracked.

 

I was sick with flu symptoms/no fever since last sun. So i did suspect maybe CO poisoning... but maybe just by chance it's the longest cold i've had, since I got couple of CO meters few days ago and it registers 0ppm.... even after placing on vent for few hours. The last guy that came also had a meter, he held it up to a vent and could not see anything significant (jumped to 1 here and there, he said that's normal).

I could not see very well with my flashlight inside the heat exchanger. From opening one of the compartments, i can see it externally.... looks like some rust around the edges, not the whole thing.

If i can't measure CO does it mean it's not cracked? Anything else could cause it? they measured gas pressure was on low end. Any chance rollout switch is flaky? (first guy did measure with a temp probe, it reach ~280F when tripped...later when he reset and let it run it didn't trip, and temp stayed ~200F).

 

Just to get heat, I bypassed the flame rollout switch for now. I'm scared to leave it like this for long. I think the sensor is probably ok, since temps there are getting to 450f & it's rated at 300f.

I posted this 2min video (sorry for low volume) -- maybe it gives some clue some of you experts will recognize for root cause:

Icp furnace issue - YouTube

Thanks so much, really appreciate any tips... (is there any cleaning/maint needed maybe on the exchanger?)

 

http://icpindexing.toddsit.com/docum...6204130500.pdf

The left burners look like they may have a problem.
I see that the insulation from the unit top is resting on the rollout switch. Did anyone remove the top and inspect the heat exchanger?

Bypassing a rollout switch is very dangerous.

 

I don't work on these units but just making some oberservations.

You definitely have a problem there. The flame looks clean. Air mixture looks ok.

You're right in what you said in your video the flame isn't getting sucked into the tube.

I'm guessing the draft inducer draws the flames down thru the unit. Logic would suggest that the heat exchanger may be restricted.

I'm wondering if the inducer blower you just put in is moving enough air.

Check this.......when the unit first calls for heat......before the main air blower starts.....see if the flame is "sucked into" the tube on the left.
If the flame looks normal there.......and when the blower starts has the issue......you more than likely have a cracked exchanger.

 

Does the flame ever actually rollout or does the switch just keep tripping? I would replace the rollout switch and reconnect it.

 

No, they did not remove the top. First guy acted like he did me a favor that he opened the panel in the back. He said he saw no 'eyelets' dropping from heat exchanger (not sure what this means), so it was probably ok.

Thx for that diagram, that's what i've been working of to see the parts. I've been thinking of removing another panel to inspect it better.... wasn't sure if it's better to take off the top one or the side panel (M). Maybe the Top to avoid messing with gas/electrical... though that has that fan... i guess i lift it up with it? hmm... maybe i'll try. Could it be a problem before the heat exchanger? When you say u see a problem with left burners u mean since flame isn't sucked in? Could it be gas pressure too low? what sucks in the flame? the inducer fan? or gas pressure? (since i understood from reading the inducer fan is something that used to not be in furnaces).

 

The inducer pulls the flame into the heat exchanger.
The side panel might not let you see the 2 left burners.
I'd turn off the breaker and the gas valve, unwire and remove the fan before removing the top.

Does the flame change after the indoor fan motor starts?
The right burner appears to be thinner in the video and the left appears thicker as if pushed by air (tough to tell though). If this occurs when the indoor fan starts it would point to the heat exchanger.

 

Here's video of flame startup: Icp furnace startup - YouTube

I don't see a difference when indoor fan kicks on (~30sec u hear the click when it starts).

I started getting top off, but the AC fan has wires running into the compartment through a tube, and I couldn't find easy way to detach (yet).

I took off inducer motor and the plate covering bottom of heat exchanger ports -- they do look rusty inside, but can't see any damage... i vacuumed there, though didn't help.

Could maybe too much gas pressure cause it? (just thinking maybe it sprays too much in the section where see flame rise near ignitor)... i wonder if i can test by closing valve a bit. The other thing, when I put on new inducer fan, I didn't have the gasket (felt-like material)... though I kinda doubt it, since it screws in there pretty snug... it also worked for a full week after I swapped. Would a cracked heat exchanger always cause CO in house?

 

This morning, I turned down gas valve and i could see the flame that was rising near ignitor go down dramatically. The gas valve is almost all the way off.

Now it seems ok at least in quick test... temps are very low, around 80 while flames running. I can't see any negative impact yet (at least in how flames look).

I hooked up the flame rollout switch again... so now i can feel safe to go to work.

What do you think? is it safe to not have gas valve open all the way? If this ends up solving it, does it indicate gas pressure issue could be problem (it's strange since guy measures and said it was on low end).

 

Turning the gas pressure down will probably cause a carbon build up in the heat exchanger.

No one on this site will tell you that this is safe. Bypassing safety switches isn't safe either.

I would consider the heat exchanger unsafe until proven otherwise at this point.

Get it inspected or get a new unit, and get the gas pressure checked.

Be Safe...

 

Thanks a lot for your advice.

I am getting new furnace... since replacing HX is $1500.

This is just to limp along as I'm waiting for quote (it's ~20 degrees outside here). Gas company came to check, pressures are fine. When I close the valve, it falls below furnace operating recommendation. He did measure exhaust and saw CO in the 1000s of ppm... he said it shows heat exchanger is clogged or cracked. He measured 0 at the vents inside house.

If anyone has suggestion for good company in STL, Missouri, let me know.

Thanks again for tips.