I have a nearly 7 year old natural gas furnace located in the attic of my 2 story home. It's a builder-grade furnace made by Goodman.
Gas supply comes in past the tee with the drip leg and goes to the gas solenoid valve. After the valve there are 4 orifices. The HSI is at the first orifice and the flame sensor is at the fourth one.
Situation:
* vent motor turns on
* HSI heats up
* gas flows
* there is a blue flame shooting out of the 1st orifice, but the 2nd, 3rd, and 4th have nothing
* gas flow shuts off since no flame detected out of 4th orifice
* However, sometimes it all works fine without any intervention
Question: what do I need to do for this to always work properly?
Repair attempt #1: HVAC tech does a cleaning on the burner mostly consisting of a lot of tapping on it trying to knock out a suspected plug. It worked afterwards so the tech left, but the problem returned overnight.
Repair attempt #2: the company sends a different tech who removes the burner and orifices, takes them to his van, and blows nitrogen through it all. This doesn't fix anything--the problem remains. The tech thinks it may be the gas valve but does not have a manometer to verify this. His price for a new gas valve is $530.
Repair attempt #3: I bought a new gas valve from someone else for $100 and a couple pipe wrenches. I replaced the valve myself. Unfortunately, the problem is still there.
I don't know what to do next.
Picture of my Goodman furnace:
Closeup of the burner where there is a flame out of the first orifice but not any of the others:
You can see: the gas valve that I replaced; the HSI at the outlet of the first burner orifice; and the flame sensor at the outlet of the fourth (last) burner orifice.
After the HSI lights up that first gas jet, how is the flame supposed to propagate to the other gas jets (assuming there is gas flowing out of the other orifices)?
No expert...but I just saw this asked/answered in another post...
I think it is supposed to pass from one to the other via those wings out at the end of each burner/orifice.
Maybe your gas pressure is low? How can they send someone who can't check gas pressure..thats just stupid
Sounds like you have the same problem as did this other poster.
http://forum.doityourself.com/gas-oi...-lighting.html
The most common reason for burners to fail to light is dirty burners ---- but a repairman who removed, blew them out and presumably inspected them should have solved that possible problem
Low gas pressure from the utility is definitely worth checking.
Then you have the replacement gas valve. Gas valves have their own pressure regulator built into them, and it's unlikely that a DIYer has the skill to correctly set the burner input, which is why DIYers shouldn't replace gas valves.
Just guessing, but it probably didn't need replacement anyway.
After reading the first post in the thread AND looking at the pictures, I tend to agree the problem is one of gas supply.
The one thing that really caught my eye was the flex line. It looks awfully small to supply a 80-100K input furnace. On the other hand, if it has worked well for the past 7 years...
You need to call the gas or service company get them to check the gas pressure. Do you have other gas appliances if so, do they work properly?
I will remove the wings and make sure the slot at the end is clean. (Just to be clear, the wings are those V-shaped extensions on the tubes?) I did take a closer look inside the ports this evening and noticed some blown fiberglass insulation trapped in there. I removed that using a solid 14ga wire, but that didn't improve the situation. Anyway, after making sure the wings are clean (thanks for the suggestion), I'll call in the gas company to check the pressure if the problem persists.
I have a gas water heater and a gas stove/oven. Both of these appliances work fine. They are all fed from the same supply line--just tee'd off. It's been this way for years. It's only now that we have this issue with the gas furnace.
Something else I noticed tonight is that the first time it tries to light, the flame in the first port has a lot of yellow and orange. The second attempt is mostly blue. The third and final attempt is solid blue. Is this useful info for the diagnosis? Keep in mind all four ports usually light up after a few runs through this cycle.
Two repairmen out and nobody has a manometer and the skill or wit to use it. One of my pet peeves.
It can be difficult to know if a repairman who shows up on your doorstep is someone you want working on your furnace.
My theory is that people should ask the repairman to show them their manometer. If they have no manometer ----send them packing.
If they have a manometer and it's nice and shiny and new ----send them packing. They obviously don;t use it, probably because they don't understand use it.
If they show you an obviously used manometer and a bunch of odd lengths of rubber hose and barb fittings ---- don't let that guy get away! He's the one you want!
'
Originally Posted by Brucifer
* However, sometimes it all works fine without any intervention
This is the most interesting of anything said. You'd think constant no start if low pressure. I'd try to light #4 burner with a long match lighter as the HSI glowed and #1 burner lit, to see if it simply a crossover problem. And I would do the test repeatedly, it it goes, to rule out coincidence. Then do it again, repeatedly, without the long match test.
But this all would be contingent on there being an oriifcie for each burner, in the rail, just in front of the shutters. If there are no orifices, and instead, gas passes through slits in the wings, then it could be low pressure, or plugged wing holes.
Heh, heh! I'd be cautious about Ecman's test. You can wind up with a face full of flame with delayed ignition from three main burner orifices.
Originally Posted by SeattlePioneer
Heh, heh! I'd be cautious about Ecman's test. You can wind up with a face full of flame with delayed ignition from three main burner orifices.
That is why he has to have the long-match going when the HSI glows, so the match flame beats the gas. If nothing happens right away, as the #1 burner fires off, turn off the long match.
The change in flame color makes me think there is junk of some sort either in the burners, manifold, or gas line, probably manifold or burners.
Originally Posted by ecman51`
This is the most interesting of anything said. You'd think constant no start if low pressure. I'd try to light #4 burner with a long match lighter as the HSI glowed and #1 burner lit, to see if it simply a crossover problem. And I would do the test repeatedly, it it goes, to rule out coincidence. Then do it again, repeatedly, without the long match test.
But this all would be contingent on there being an oriifcie for each burner, in the rail, just in front of the shutters. If there are no orifices, and instead, gas passes through slits in the wings, then it could be low pressure, or plugged wing holes.
Yes, there are 4 orifices threaded into the rail. Each sticks out into one of those 4 long tubes with wings.
There are times when the system hasn't run for hours, then the thermostats calls for heat, and it all works fine. Typically, once it gets working (all 4 lit up) it will be able to do that repeatedly for hours as needed to maintain the thermostat setpoint.
It seems to be the worst early in the morning. That's most often when we have to turn the system off and on until it runs. Turning it off and on is the intervention I was talking about. The only consistent thing about when it works is that it's inconsistent.
Originally Posted by Grady
The change in flame color makes me think there is junk of some sort either in the burners, manifold, or gas line, probably manifold or burners.
I'm ok to take all of the piping apart and the orifices can be unscrewed. If there is something in there that blowing nitrogen through it couldn't dislodge, what would be the best way to get in there and clean whatever out? Poke around with a wire? Pound on it with a mallet?
His light is on. He sure has quite a bit to read now.
In all my years, I have dealt with similar issues a lot, with gas ranges. And how one burner will go, every time, and another won't. And you'd have to wave your hand at it to get it to go. And invariably it was always one of those small step-up holes, I'll call them, that allow the gas at the top of the burner, to also come out those step-up holes (that progressively got 3-tiers lower... down to the level where the pilot was), to reach the pilot flame. The pressure was there at the source alright - except that gunk was blocking them holes.
Hmmmm. You say the 2nd tech cleaned the orifices and burners out in his van. He blasted them clean. Hmmmm.
Did anyone, just to be certain, make sure the pressure switch is not shutting off, because it is always marginal? That be easy to forget about, under circumstances that mimmick flame sensor and low gas pressure problems. I am a real, real stickler for not letting Murphy play games with me. I really mean that too, not just to be funny. Just like how your phone rings everytime you go to use the toilet.
Start with the easy stuff, the burners. Take them out clean 'em yourself paying particular attention to the interior of the wings.
Sounds like you've been dealing with the world's largest HVAC company, GTMR, better known by their full name, Get The Money Run.
Originally Posted by Brucifer
I'm ok to take all of the piping apart and the orifices can be unscrewed. If there is something in there that blowing nitrogen through it couldn't dislodge, what would be the best way to get in there and clean whatever out? Poke around with a wire? Pound on it with a mallet?
Usually I clean burners with eith a regular wire brush or a toothbrush sized wire brush with finer wires.
But I'd use a piece of sheet metal or whatever it took to clean out any debris.
Knocking debris out by lightly pound on the burner is an old serviceman's tradition, but pounding can be overdone and could bend or damage something. So a measure of caution is recommended.
Also, moving the burners around to see if that changes how things light up might be worthwhile to try.
Originally Posted by SeattlePioneer
Also, moving the burners around to see if that changes how things light up might be worthwhile to try.
Excellent idea! Yes. That worked for me with problem gas stove burners when trying to figure out if ther really was a gas pressure issue from some orifice, some alignment issue, or whatever..
But maybe you can only switch around the 2nd and 3rd burners, since the left burner may not have a wing to the left, and the right burner may not have a wing to the right. This dawned on me just after I left the board to go out on a job.
I had the same problem and just fixed it. Take the burners out. it is important you remeber what order they go. at the end of the burner where the flames are there is aoriface that gets plugged! simply clean all around that oriface. I used a big tie strap and simply clipped it untill it fit. clean all the holes, then take a flat putty knife and scrape the inside of the wings, blow it out with air, replace and it should fire all of them, hope this helps.
Dirty burner orifices could cause that kind of problem. The usual thing to do is to remove the burners then unscrew and remove the orifices.
They can be inspected and cleaned easily at that point.
Reporting back now after letting the system run for awhile. The rail and orifices were all fine and clean--they weren't the problem. I had to dig out small bits of the blown fiberglass insulation out of the notch in the end of the wings using a utility knife and compressed air. There wasn't much there, but apparently it doesn't take a whole lot to disrupt the flame propagation across the wings. Thanks to all for clueing me in on where to look for the problem. It's a shame that I wasted money on service techs who didn't think to check there for the problem as well. I probably wasted money on replacing the gas valve as well.
Glad you got it. Too bad techs did not figure that out.
Just wanted to add my experience to this thread. I've owned a janitrol GMP 075 forced air furnace for about 10 years now and I've always had the problem of the burners not lighting the first time. And, to make a long story short, I had to finally take off all three fans and clean them with a wire brush and blow them out really good (paying close attention to the sides of the fans where the flame jumps from one to the next). It looks a little intimidating at first to remove the parts but just take your time...it can be done. I put them all back together and fired the furnace up and adjusted the gas output a bit with a flathead screwdriver and now it fires up first time...everytime! Makes me mad I didn't do it sooner. Luckily though I never called anyone out for a repair...I could see someone taking you to the cleaners on something like this. Like the person above said...do the simple things first.
Tags: furnace, sometimes, only, lights, first, orifice, four, Originally Posted, long match, burner orifices, there orifices, around that, burner orifice