Crazy Banging Noise that Service Guy Cant Fix After 3 Visits

[dmfelder]

I have a problem that has persisted for several years. Each year, a service guy tries another solution. The heater bangs like crazy, and it's not the ductwork. We have cleaned it, replaced the mother board, checked the gas pressure, checked the voltages, cleaned the flame sensor, and replaced the gas valve, to no avail.

Here is a video I posted online. It's pretty dramatic. Any ideas? http://garmentdeli.com/Furnace_Banging_Noise.wmv

[Chris_Worthington]

Relocated to AOP

[BaldLoonie]

Anybody take the shipping bracket off the blower motor? Couldn't tell for sure what you have but some of the bigger VS blower models have them. Beyond that, nothing we've encountered in a Rheem.

[second opinion]

I have a problem that has persisted for several years. Each year, a service guy tries another solution. The heater bangs like crazy, and it's not the ductwork. We have cleaned it, replaced the mother board, checked the gas pressure, checked the voltages, cleaned the flame sensor, and replaced the gas valve, to no avail.

Here is a video I posted online. It's pretty dramatic. Any ideas? http://garmentdeli.com/Furnace_Banging_Noise.wmv

Is there a humidifier on the furnace?

[Chris_Worthington]

That would drive me insane. As loud as it is I am surprised that, that sound would not point towards a focal point for a look...

1.41 minutes before the fan cycles on after a call for heat sounds excessive to me, Loonie what say you?

Could it be something expanding that should not be??

[dmfelder]

Oh...it's LOUD. It resonates through the house. It doesn't bang all the time, either, which makes has made it difficult to diagnose (and the tech can't wait around all day). And, as luck would have it, it tends to bang all night.

There IS a humidifier on the system. A friend thought it could be related to the heat-exchanger, but offered no further advice.

The furnace is a Rheem RGRA-12ERAJS
Rheem Classic 90 Plus Premium Efficiency
Board part number: 62241140-02 (model 1028928)

It has a "General Air Bypass Humidifier"
RCBA-4882GG24

Regarding a shipping bracket, let me mention that the unit is 8 years old. It worked perfectly until about 3 years ago (when the banging started). Nothing had even been serviced prior to this issue, and I have always been standing with each technician. So, my intuition suggests it's not related to something that may or may not have been removed.

I will say one other thing. Sometimes, when I'm just standing near it while it's functioning, watching the flames through the little window, it "puffs out & extinguishes." Literally, the upper panel pushes out a little bit and you hear a slight "swoosh" sound.

We've literally gone through what appears to be standard protocol with the diagnosis. We've replaced everything obvious, and checked voltages, gas pressure, etc.

Might something like this be caused by "gaps of air in the gas line, or lack of gas all together?"

It's kind of funny at this point. It's like a baby waking us up in the middle of the night.

...but it's not really that funny!

[Chris_Worthington]

I'm a little worried about your heat exchanger as well....

Do these guys have a camera they could snake in for a pic? A bunch of companies now do.

[dmfelder]

I'm the one who made the video, so perhaps I could do something with enough instruction.

I'm a mechanical engineer so I'm not really afraid to tinker (or problem solve). I just don't really understand the function of the heat exchanger well enough to know how it could possibly result in banging.

[Chris_Worthington]

"If" I were you, I would share this video with your service companies service manager and see what he has to say about it and as to why his guys missed it.... after that I would seek out another service company for their 2 cents. JMO

[johnt2_2002]

definitely not a good sound. Not overly familiar with rheems 90% furnace in terms of the heat exchanger design. but I did have a rheem mid-efficiency furnace last year where the weld holding the tube to the header box was broken allowing for the HX tube to be moved out of place. Might have a broken HX tube in yours........

[second opinion]

I'm the one who made the video, so perhaps I could do something with enough instruction.

I'm a mechanical engineer so I'm not really afraid to tinker (or problem solve). I just don't really understand the function of the heat exchanger well enough to know how it could possibly result in banging.

Look in the dealer locator and also post your location and possibly there will be some one on here that can help.

Heck if you are any where near my I will look at it just out of curiosity.

Is there any type of pattern, like it will always do in the afternoon or morning. or is it quiet random?

[dmfelder]

I'm in Chicago if anyone wants a look-see. If anyone knows the local "Rheem Master" in Chi-town, please let me know.

It's quite random, but I seem to notice it more in the middle of the night. And when it DOES bang, sometimes it's only once or twice. I had a camera on a timer for quite some time because no one would believe me when I described how bad it was.

Here's another thing, although I'm not sure it offers any clue:

I'm in a two level home. The heater is below me (sub-grade) and about 20 feet south of my bedroom. There is a gas line that extends under my bedroom and through the back wall of my home (presumably for a natural gas grill). My bed is against the exterior wall. From my bedroom, it sounds like someone is hammering outside, just on the other side of my bed. In addition, I can hear it somewhat prominently in the kitchen (gas stove). So, it's clear that the pipe is acting as a conduit of the noise throughout the house.

This may be obvious to you "HVAC guys" but the fact that the noise is traveling through the house along the pipe might give you some more insight to its origin.

[Chris_Worthington]

How ever this gets figured out, you're gonna have to let us know now what it was :cheers:

[Danimal535]

looks like in between the banging the unit is flashing a fault code but i cant pick it up from the video has any one checked the gas pressure?

[dmfelder]

We checked the gas pressure with one of those water gauges. I don't remember the exact pressure, but the guy said it was normal (and it was consistent). I feel like it was 4" but that could be WAY off!

Now...here's some more information since you mentioned gas pressure:

I also have an auto-light (spark) gas fireplace downstairs. I have the exact same fireplace upstairs. When I turn the one on upstairs, it clicks ten times and then fires up without a problem. Sometimes, the downstairs fireplace takes two cycles. I keep my house VERY cool in the winter (59 at night), and downstairs is always at least 10 degrees colder than upstairs.

I once thought it was a gas pressure issue, but over time I kind of concluded it was related the the temp and the thermocouple.

Again, keep in mind that I didn't have an issue for the first 5 years of its life.

Also, I installed a tankless hot water heater last year, and the city of Chicago upgraded my valve outside.

[johnt2_2002]

watched the video a few times, really hard to say. I wonder if the regulator on the gas meter is faulty, especially when outdoor temperature drops. Might be allowing some gas through enough for ignition and than locks shut.

But even still, the noise sounds too loud to be the gas valve in the furnace when it shuts off on flame sensor.....

regulators can fail on gas meters, hopefully all the gas piping is sized correctly as well.

wish I was close by to take a look, real curious as to whats going on.

[Shophound]

I will say one other thing. Sometimes, when I'm just standing near it while it's functioning, watching the flames through the little window, it "puffs out & extinguishes." Literally, the upper panel pushes out a little bit and you hear a slight "swoosh" sound.


This isn't right, regardless of cause.

Has anyone performed combustion analysis on this furnace? Has the exhaust piping been checked for obstructions? How does the exhaust terminate once it is outside your house?

Also, being a +90% furnace, has the condensing section been checked for obstructions inside the tubing?

[johnt2_2002]

anyone else notice that the noise on start up at :07sec., is similar to :54secs and 1:33.? Tstat, wiring, relay issue somewhere is possible......:gah: let us know how its resolved.

sometimes the problem is right under your nose and the solution is ridiculously simple!

[beenthere]

coolwhip, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

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[beenthere]

bacciagalupe, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

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[dmfelder]

So to reiterate a few things:

1) the furnace is 8 years old. It functioned absolutely well for 5 years, then it started to bang. In other words, the furnace has been banging for 3 years.

2) the new hot water heater was installed last year, as was the new outside gas valve.

3) we checked the main relay once before and it seemed to function fine. We also replaced the furnace gas valve & motherboard.

No one has performed any time of combustion analysis. When it fires up, it seems to work fine. The system terminates outside (behind my bed) with a dual PVC piping.

Are you ready for another curve ball? Sometimes when I'm outside, a fair amount of water (~6-8 ozs) is pushed out of the larger/center pipe. (Maybe I should have mentioned that first, but I guess I thought it was normal.)

[Shophound]

Are you ready for another curve ball? Sometimes when I'm outside, a fair amount of water (~6-8 ozs) is pushed out of the larger/center pipe. (Maybe I should have mentioned that first, but I guess I thought it was normal.)


You may actually be providing more info toward solving the problem.

Check the exhaust pipe that leaves the furnace and heads over toward an exterior wall to where it exits the house. Does that pipe slope upward, away from the furnace? Get a level and check it. It could have shifted position since the furnace was installed eight years ago.

[BaldLoonie]

I think someone mentioned the humidifier. Listening to it carefully at home that well could be a hum solenoid hammering for some reason. I'd unwire it or turn the humidistat down to rule that out.

Chris caught the quick restart after shutdown, that sure isn't right. Something shut it off. Blocked drain switch shuts down the fire by the gas valve. Main pressure switch or limit shuts the furnace through the board. Usually if they shut it down, it goes through the blower shutdown and immediately restarts. Something else that should be looked at.

[NCHeat]

Does it happen more when we have colder nights? Whet do you mean by 6 or 8 oz. of water comes out of the vent? All at once? over a period od 30 min? I have a pressure problem in my head right now

[Danimal535]

Ok now is sounds like you have a drainage issue and the pressure switch is cycling the gas valve next time it happens right after the first bang count the indicator light slow flashes then fast flashes

[tinknocker service tech]

that noise doent sound good
i tend to think you may have a broken motor mount or loose one
seems the noise starts just about the time the blower is coming on and it doesnt the after a minute or so it does
also notice the flame is shutting down then after a few seconds comes back on again leads me to the blower
have your tech check the wheel for alianment and motor bracket

[dmfelder]

The water dumps out all at once in a "wave". It comes out of what I believe to be the exhaust vent.

And yes, it seems like it happens more on colder nights, but that might just be perception.

[BaldLoonie]

Ah ha, look for a SaG in your PVC flue pipe as it leaves the furnace to outside. Downhill slope all the way back to the furnace. If not, could be some chatter of the pressure switch causing the gas valve to cut out. I heard a Trane do that once.

[second opinion]

I think someone mentioned the humidifier. Listening to it carefully at home that well could be a hum solenoid hammering for some reason. I'd unwire it or turn the humidistat down to rule that out.

Chris caught the quick restart after shutdown, that sure isn't right. Something shut it off. Blocked drain switch shuts down the fire by the gas valve. Main pressure switch or limit shuts the furnace through the board. Usually if they shut it down, it goes through the blower shutdown and immediately restarts. Something else that should be looked at.

I mentioned the humidifier only because it sounds like a solenoid or relay is pulling in and out rapidly along with the fan making and that is when EAC and HUM should be energizing.

I also had this same scenario when I was a Trane rep. numerous dealers had visited the customer it became a consumer complain and I did a field visit and found the humidifier solenoid vibrating rapidly, sounded like a hammer drill when it echoed in the duct. It was intermittent only when humidistat called.

I was also wondering is the recording continuous or patched because the time line is strange and the unit drops fan out but sound as if burner is still going then fan starts again.

[second opinion]

Second I agree with humidifier. I've heard it before, disconnect solenoid wire and see if sound goes away. This board should have a hum tap. The time I experienced it, unit had a current sensing relay.

A weak transformer or low primary voltage can also be the culprit when multiple controls are pulling in simultaneously.

[beenthere]

alimoges, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

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[heaterman]

Leaning toward a drain, water, vent issue. That's a solenoid and it's the same sound that you hear at the 7 second part. Also needs checked for moisture in a vacuum hose.

[dmfelder]

Several of you folks are seemingly a little worried about the water for various hypotheses. I'm going to start by turning off the humidifier completely to eliminate the possibility of excess water contributing to the issue. I unwired it, and I turned off the water supply. I watch/listen for a few days and report back. It's supposed to be cold here this weekend with a fair amount of snow.

News to follow...

[BaldLoonie]

And look at the PVC exhaust pipe for a sag too.

[Willserve]

I will say one other thing. Sometimes, when I'm just standing near it while it's functioning, watching the flames through the little window, it "puffs out & extinguishes." Literally, the upper panel pushes out a little bit and you hear a slight "swoosh" sound.


I agree with Baldloonie, check PVC exhaust pipe for a sag. The unit sounds like it's starving for air and sucking in the panel because exhaust is filling with water.

[pacnw]

Where does the compensate drain to?
Post some photos of the PVC lines and the outside PVC termination.

[pacnw]

Notice the LEDs. Starts out as 2, with the left one dropping out when there is the noise.
Around the 5 minute noise there are 3 LEDs and all stay on.
Someone with the fault code legend should be able to point in the correct direction for diagnostics.