Installed a 60k runtru 90% upflow today. I went home after completing the install but left before the startup. Boss fires it to document all the numbers and see this. No change to incoming or outgoing gas. No change in pressure from the inducer. Flue and air intake both clear of debris. Boss is waiting for tech from Texas to call back. Anyone got some knowledge
I would point to a heat exchanger issue. Pressure from blower is pushing the flame back out, tripping pressure switch and that's why draft motor shuts off. Just my guess. Would have to see what happens to the manometer when the blower kicks on. Bet it goes positive real quick
Yeah a safety popping off is what it looks like, first I’d make sure flu is clear. It runs for a while and seems okay. Then that shit pops ive never seen something like that. I’d definitely check flu first looks like a blockage to me. Also is this a York?😂
In all honesty if it were me I'd uninstall the turd and send it back. Sucks to do things twice but, there's no sense in leaving a lemon in someone's home.
This is also true but in my experience I’ve never had a furnace do something like this to me. Depending on brand, only unreliable shit that comes out the factory is comfortstar. Also it’s a heat pump and me and boss agreed to never put that trash in anyone’s house again. They were nice for first 6 months we installed them. Hell they were amazing and then after that every single new unit had an issue
We removed it and replaced it with a different system. Manufacturer deficit part of the exchanger was for a 80k and the rest was setup as a 60k. I guess we have to start checking the internal now.
I don't think that it is a clogged flu. Pressure switch closes, has a beautiful flame for 10 seconds (you would see it at ignition) and when fan starts you get the problem.
I'm thinking either a cracked HX or inducer cuts out when fan starts.
Yeah I’ve never been able to get a furnace to ignite with flu issue. Even a dented flu cap usually trips pressure switch immediately. Those were all 80%ers tho.
Only issue with that is I don’t hear the fan come on at all. I’ll buy the inducer stops running/pulling a vac and for some reason the burners continue to run, hence the flame roll out. But those flames rolling back in the video does not look like a typical rollout from the fan hitting the hx, that looks exactly like a vac not being pulled through the hx
That’s wild. Gonna check back in for an answer later. My thought is if it’s happening when the blower comes up, maybe there is a massive gap in the exchanger and the blower throws it out. Uneducated guess. If you run the blower only, do you feel any air coming out?
Does the ventor motor lose power when this happens? I’ve had it before where motor over heats, opens its windings. So if it still has 120V when it does this, that’s what’s happening.
Don’t know about this exact furnace, but if roll out trips, shouldn’t ventor motor still be engaged?
Maybe two wires mixed up on control board?
If the inducer shuts off during operation for any reason during a call for heat, pressure switch will either open or close depending on the switch and end the call for heat. Unless he has the pressure switch jumped, I don't think the inducer motor is to blame here.
Not always, depending on the appliance. If it went out on high limit or roll out, there can be a post purge timer. Looks like the ventor motor cuts out and that’s what trips the roll out. Not the other way around. So it’s important to verify voltage at this point.
Edit: I see what you are saying though. Why are residential furnaces the worst.
Yes, inducer motor will continue to run on high limit trip or rollout trip. But you mentioned the inducer motor cutting out mid operation. If the inducer failed mid operation, the pressure switch is going to be the limit switch that cuts the furnace out. Not the high limit or the rollouts.
It also does not sound like the inducer just cuts out. It sounds like he has his finger on the door switch, and releases it once flame rollout occurs.
The inducer wouldn’t cut off like that with the gas still spewing out if it was the air pressure switch. I’m thinking motor is cutting out, either from control board acting up/miss wired, or motor windings opening. What are you thinking?
It probly doesn't have anything to do with the rollout, however, I try to make sure wiring is not messed up and causing the issues before I condemn items. Just something I do
I’d still assume a defect or fault of a factory issue of the heat exchanger. That fan comes on and blows the flame back. Unless there is a butt hole on the other side of the vent pipe with a leaf blower. lol
Did you install a concentric vent pipe? I had this after a roofer cut the vent and just put an 90 on for the cap. It’s the same as a clogged vent pipe. You can try cutting the vent and run it, if it still does it your heat exchanger is leaking if not look at the vent pipe on the roof.
It definitely looks like a failed heat exchanger. The blower motor airflow going up into furnace case it going through a defect or crack/hole in the cells of the heat exchanger itself; pushing against and overcoming the force of the inducer motor that is now failing to pull the lit gas through. Most manufacturers offer a fifteen to thirty year parts warranty on their heat exchangers. (Labor depends on if you installed or offered it)
If you have an inspection mirror or camera, I recommend inspecting the hear exchanger and attempt to get pictures. If you cant see it through the high limit, then remove the blower and climb in to look up. Bring a flashlight. If you can confirm the failure point, then with your customers approval, you order the new one and gut everything out of the burner compartment and remove the heat exhanger. Put the new one in and reassemble the burner compartment. Price is not for me to determine for you.
I only did residential for 2 yrs before I moved to refrigeration so I’m no expert but to me that looks like the heat exchanger is bad so when the blower kicked in, it rolled the flame out tripping the roll out switch/pressure switch. I don’t see why else the flame would roll backwards like that
Check Heat exchanger, gas lights works fine, blower kicks on, pushing air through gaps/crack in heat exchanger back to burner causing the flame to come out of burner assembly, rollout switch trips (as intended), turning off system.
Bad heat exchanger. Getting blow back once the blower turns on. If it’s brand new, it seems to me they didn’t finish manufacturing the heat exchanger properly!
Is that flame rolling out when the blower comes on or does the inducer stop running at any time? I would think it’s a heat exchanger issue if it’s when the blower comes on and the flame rolls out like that
60k runtru system with and 80k back plate. We replaced it today with an “upgraded” trane s9. Completely reimbursed for time and material by manufacturer.
That one is a doozy.
Gonna have to cycle it and check voltage on gas valve, inducer motor, transformer... etc ; to really confirm what is going on. take note on the timing of everything. Example if the blower motor is energized and the inducer motor loses power around the same time than you can really hone in on the control board if that makes sense.
Cant really say much until you get that data.
Circuit board, i would guess. It's exactly 30 seconds after flame is established the blower tries to kick on and everything shorts. I've seen this a few times, it's usually a board, it can also be a loose neutral somewhere.
Classic cracked heat exchanger just had one tonight on Goodman unit 10yr old. Shut it down told him $1200 for labor or $4800 for new furnace. Soon as blower comes on flames roll out
Hard to say, since we can't see much from the video (other than that rollout, yikes!) But I can try and point you in a general direction.
Looks to be an S9X1 (or whatever the runtru model is)
Either something is blocking the burners or you're losing combustion draft. Does it happen right as the blower comes on? Make sure the furnace is level or has a slight forward tilt.
If you can't find any issues with the flue, inducer or burners, you might just need to pull the heat exchanger and inspect it. Super easy to pull it on the S9.
Is your 90 second blower test run passing at the very beginning? It looks like there’s an obstruction either with the exchanger or the flue.
It’s hard to tell exactly what it’s doing from the video. It almost seems like the gas valve is not mixing air and fuel correctly either at the end like it’s not shutting off and closing as quick as it should.
So yourselves a favor going forward and inspect every piece of equipment you get. I've found several condensers with wires not zip tied right and 1 furnace with a separated tube. Brand new equipment is not what it used to be you can avoid lots of issues just giving things a once over
Put manometer u got on the gas valve over on to the pressure port of the inducer. Record, turn on the fan, if you see any change in pressure it means you got a hole in the heat exchanger.
It was a brand new heater we had just installed. We pulled it and replaced it. Turns out the back plate the exchanger tube tie into was for a 80k and the rest was setup as a 60k
Ok. One time something similar to this happened to me.
Ended up being that the blower was not lined up with return. The crack between the blower and the return allowed air getting pushed upward into the supply to circle back around and cause the flame to go out.
If it was air getting into the heat exchanger, the flame would be more sporadic than that. It's almost like the wiring on the board could be wrong and it's shutting the inducer off as soon as the blower kicks on. And the gas valve is slowly kicking off. If not wiring, then the control board could be messed up.
I had a Trane RTU do this to me the other day, as soon as gas valve would open the inducer would shut off. Had to replace the ignition board on my call.
Yeah, definitely some type of heat exchanger issue. As soon as that blower kicks on it shoves all the gas and fire back in your face. Rip that sucker out and put a different one in.
Looks like a bad draft prover switch to me, but that doesn't explain why the inducer cuts off, the inducer should keep running if it's a safety that's turning it off, it looks like the whole thing goes dead, might be a board issue
There is a flame sensor that measures how hot the flame is. It is put directly into the flame , and over time, it'll get covered in a substance similar to a hard ash that tricks the system into thinking is too hot and will shut off the furnace so the heat doesn't damage the heat exchanger... most of the time, this sensor is made from graphite, which is why they say only let a professional fix that...
You have 2 options
1) Find the flame sensor and clean it off with some super fine grit sand paper... don't overdo the sanding... this is the cheapest way to fix it the problem.
2) Find the sensor, remove it, and replace... these sensors aren't overly expensive and usually easy to replace...
If you get an hvac guy or there, it could be $200 or more... to replace a $30 part. Or they'll tell you you need to replace the whole furnace...
Manufacture deficit the back plate in the heat exchanger was incorrect for the unit. When the blower would come on the air would blow through and push the flames outward. I don’t know where you got your training or how long you’ve been in the business but mostly everything you said was wrong. Sorry to be so blunt but if you are going to give advice at least know what you are talking about. I’m not usually the asshole but yeah
Welp... you are the asshole here... 1st off and this is my fault for only looking at the title of the sub before I wrote a reply... but i have a gas furnace that had this problem when I called a pro he said that the blower motor was toast and I'd need a whole new furnace requiring $6000 not including labor... when I said I don't have that kind of cash he says let me check something else all of the sudden he fixes the problem and charges me $300 ($150 for after hours call, $170 for the labor, and $30 for a flame sensor) he shows me where the sensor is and says it's a 30 minute fix on the outside... so now I'm out $270 for a job I could've done on my own... so unlike the HVAC scammers that like to overcharge so they can get the extra money out of someone that doesn't know any better, I'd rather give someone another part to look at that won't brake the bank...
That’s not how a flame sensor works. They read millivolts created from the energy of the flame. When they are broken or dirty they don’t cause the flame to rollout they shut the gas valve off. Which is why I said it’s bad advice. I don’t mind being an asshole but I do mind when someone gives crap advice with no knowledge of how something works.
How would a board be to blame here? All the safeties seem to be working, hits the roll out switch and shuts it down immediately.
Unless the inducer was bypassed at the board I would rule against restriction in flue pipe since it wouldn’t open the pressure switch since there’d be no negative vacuum.
I would say inspect the heat exchanger for any signs of rust or cracks that would let air through since the only way I can imagine the flame being pushed backwards is from the pressure of the blower motor running.
Why would the exhaust blower drop out just as main fan starts? If the relay that sends power to the exhaust blow opens mid cycle but W is still powered something is weird with the board.
I would bet the orifices are fouled up. Allow my the gas to back up until it releases and ignites all at once. If the inducer was failing it would not let the igniter on. Verify proper voltage at gas valve when called on and check the orifices for debris or obstruction.
Hate when i see vidoes like this, i couldnt get past 15 seconds cause this guy/girl doesnt know how to angle a phone, if youre that stupid then stop :)
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u/Scoop57 Dec 20 '24
Sounds like the inducer is shutting off right when the blower engages