# old wall furnace makes banging noise



## KarlJay (Dec 9, 2009)

I'm moving my old wall furnace, it's fully disconnected and I want to fix the banging noise that it's made for the last 15 years I've had this house.

The house is over 70 years old and I don't have a clue as to the age of the furnace, I know it's at least 30 years old.

The furnace works fine, but when it cycles off, it makes a series of banging noises as it cools down. I don't want to replace it with a new one at this point.
Is this a common problem with old wall furnaces?
My guess would be the metal above the flame where the heat transfers is too close to a mount and the expantion/contraction of the metal is where the banging happens.
Any input / hints would be great...
Thanks, KarlJay.
I have a TIG welder and pretty extensive set of tools for metal working, so I don't mind making something that'll fix this.


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## hvaclover (Oct 2, 2008)

That could very well be a cracked heat exchanger.

Wall furnaces are dirt cheap. Why not just buy a new one since you are moving it?

You have nothing to lose except high fuel bills.


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## userCA (Mar 17, 2011)

I have the exact same problem with a wall furnace and am trying to figure out how to fix it. My landlord wants to replace the vent pipe, because he thinks the pipe is expanding/contracting and making the banging noise. But now I'm thinking it may be a problem with the wall furnace heat exchanger itself. 

What did you find out about yours? Was it a cracked heat exchanger that was making the banging? If not, how did you fix it?

Thanks!


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## hvaclover (Oct 2, 2008)

userCA said:


> I have the exact same problem with a wall furnace and am trying to figure out how to fix it. My landlord wants to replace the vent pipe, because he thinks the pipe is expanding/contracting and making the banging noise. But now I'm thinking it may be a problem with the wall furnace heat exchanger itself.
> 
> What did you find out about yours? Was it a cracked heat exchanger that was making the banging? If not, how did you fix it?
> 
> Thanks!


If you suspect a crack I would call the land lord and demand a monoxide detector for the home. In every state in rental property they are required by law.


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## KarlJay (Dec 9, 2009)

Update: I haven't addressed this issue yet, might just buy a new replacement. As far as your's having a crack, I'd go get a CO detector TODAY.
I got scared and bought one last year, everything is fine as far as CO goes.
The concern is that CO doesn't have an oder, so you can't tell if you have a leak.
Mine went off once when I had an old muscle car idleing in the driveway with the front door open. Couldn't tell anything except for the CO alarm going off.
It can KILL you...


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## unicursalhex (Jan 18, 2011)

Yeah the detector is a good idea. I did a furnace maintenance a little while ago and found a big gaper right behind the heat exchanger limit. I shut the valve off and informed the old guy who owns the place that carbon monoxide is spilling into his house and that he needs to replace the unit. Before I could get my tools loaded he was turning the valve back on and running the furnace... Just did a follow up call today and he said he's going to replace it but he has some other things that are more pressing. Wow, whats more pressing than carbon monoxide poisoning? He's an old guy so he's set in his ways, hopefully that crack doesn't open up even bigger and give him the dirt nap...


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## seatonheating (Feb 2, 2011)

unicursalhex said:


> Yeah the detector is a good idea. I did a furnace maintenance a little while ago and found a big gaper right behind the heat exchanger limit. I shut the valve off and informed the old guy who owns the place that carbon monoxide is spilling into his house and that he needs to replace the unit. Before I could get my tools loaded he was turning the valve back on and running the furnace... Just did a follow up call today and he said he's going to replace it but he has some other things that are more pressing. Wow, whats more pressing than carbon monoxide poisoning? He's an old guy so he's set in his ways, hopefully that crack doesn't open up even bigger and give him the dirt nap...


 
Risking your life is more important than a couple thousand bucks....DUH!!


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## KarlJay (Dec 9, 2009)

You might concider calling the City about that, we have people around here that DIE from time to time trying to heat their house with a BBQ and other things.
I didn't know the danger myself once. Problem with death... it's final...


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## Marty S. (Oct 31, 2009)

unicursalhex said:


> Yeah the detector is a good idea. I did a furnace maintenance a little while ago and found a big gaper right behind the heat exchanger limit. I shut the valve off and informed the old guy who owns the place that carbon monoxide is spilling into his house and that he needs to replace the unit. Before I could get my tools loaded he was turning the valve back on and running the furnace... Just did a follow up call today and he said he's going to replace it but he has some other things that are more pressing. Wow, whats more pressing than carbon monoxide poisoning? He's an old guy so he's set in his ways, hopefully that crack doesn't open up even bigger and give him the dirt nap...


 Time to call the gas company so they can lock out his meter. Remember that CO damages all the internal organs including the brain. His reasoning ability might not be as good as it should be.


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## mastertech (Mar 14, 2011)

unicursalhex said:


> Yeah the detector is a good idea. I did a furnace maintenance a little while ago and found a big gaper right behind the heat exchanger limit. I shut the valve off and informed the old guy who owns the place that carbon monoxide is spilling into his house and that he needs to replace the unit. Before I could get my tools loaded he was turning the valve back on and running the furnace... Just did a follow up call today and he said he's going to replace it but he has some other things that are more pressing. Wow, whats more pressing than carbon monoxide poisoning? He's an old guy so he's set in his ways, hopefully that crack doesn't open up even bigger and give him the dirt nap...


wow THATS INSANE!.You know as a professional in this trade we have the obligation to prevent people from harming and possibly killing themselves due to defective or damaged equipment.I would have disabled that furnace and made sure the ole boy couldnt relight the damn thing! thats sad because he probably doesnt have the money to repair it and needs it on.Some states have programs for the elderly that will actually replace at no cost a system that can kill the tenent or owner.I wouldnt have left that furnace to where it was operational at all>do you have any emergency assistance programs that do help the seniors in your area!:thumbsup:


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## hvaclover (Oct 2, 2008)

1mastertech said:


> wow THATS INSANE!.You know as a professional in this trade we have the obligation to prevent people from harming and possibly killing themselves due to defective or damaged equipment.I would have disabled that furnace and made sure the ole boy couldnt relight the damn thing! thats sad because he probably doesnt have the money to repair it and needs it on.Some states have programs for the elderly that will actually replace at no cost a system that can kill the tenent or owner.I wouldnt have left that furnace to where it was operational at all>do you have any emergency assistance programs that do help the seniors in your area!:thumbsup:


your sense of duty is commendable but in the end only the customer will have the right to close down a furnace.

our city won't enforce a shut off. its all about liability.
t


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## mastertech (Mar 14, 2011)

hvaclover said:


> your sense of duty is commendable but in the end only the customer will have the right to close down a furnace.
> 
> our city won't enforce a shut off. its all about liability.
> t


 
Is That right? wow thats crazy,the people will hold you accountable for what...saving there life! Ive never heard of that before.Ive been taught that if theres a code violation or a problem that can be life or death is to disable it.You are the last person there and if something did happen you could be held liable for negligence for not shutting it down!WOW I guess theres different laws everywhere. Well what about your consience?:whistling2:


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## kenmac (Feb 26, 2009)

All I'm able to do is turn off the gas supply to the furnace & try to get the customer to sign a form stating why I turned it off & that the furnace shouldn't be used until repaired/replaced. If they choose to relight & continue to use . There's nothing more I can do. It's their furnace & property. Gas co. here isn't allowed to turn their gas off as, they may have other gas appliances that are in use. Only time gas co. will turn gas off is if the bill isn't paid


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## mastertech (Mar 14, 2011)

kenmac said:


> All I'm able to do is turn off the gas supply to the furnace & try to get the customer to sign a form stating why I turned it off & that the furnace shouldn't be used until repaired/replaced. If they choose to relight & continue to use . There's nothing more I can do. It's their furnace & property. Gas co. here isn't allowed to turn their gas off as, they may have other gas appliances that are in use. Only time gas co. will turn gas off is if the bill isn't paid


 
yA..10-4 ITS CRAZY ESPECIALLY WHEN YOU EXPLAIN THE RAMIFICATIONS TO THEM.tHANKS FOR THE POST MY FRIEND!:thumbsup:


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## Doc Holliday (Mar 12, 2011)

hvaclover said:


> .) your sense of duty is commendable .2) but in the end only the customer will have the right to close down a furnace.
> 
> 3.) our city won't enforce a shut off. its all about liability.
> t


 
1.) I agreee and applaude 1mastertech.

2.) bull hell.

3.) Mine will. We disable systems, call the city and they will come and confirm our findings of CO and turn off the gas to the home, quickly. If the homeowner/tenant doesn't like it, too bad. At least they are alive to complain.


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## Doc Holliday (Mar 12, 2011)

kenmac said:


> All I'm able to do is turn off the gas supply to the furnace & try to get the customer to sign a form stating why I turned it off & that the furnace shouldn't be used until repaired/replaced. If they choose to relight & continue to use . There's nothing more I can do. It's their furnace & property. Gas co. here isn't allowed to turn their gas off as, they may have other gas appliances that are in use. Only time gas co. will turn gas off is if the bill isn't paid


 
Actually this sounds more of the normal but there have been a few occasions where we've called the city as the CO leak was present and the HO refused to keep the furnace turned off so the city came out and turned off their gas. It is a liability issue, ours.

If you don't want to know you have a leak and that your home is unsafe due to it than why call me out for an annual heat check up to begin with?

eh.


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## unicursalhex (Jan 18, 2011)

Well, I have informed him of the dangers and exactly how dangerous CO is and he gave me the ol' "well its been runnin for years like this" in a "I wasn't born yesterday" type of way. Hey, all I can do is shut off the furnace and inform, the rest is up to him. I have no legal obligation past shutting off the gas line and switch for the unit and having him sign the invoice saying he was informed that the unit or heat exchanger needs to be replaced and the furnace is not safe to operate. If he wants to sh!t all over my expertise and run the furnace then he can go right ahead, I'm not wiping his ass any more than that.


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## unicursalhex (Jan 18, 2011)

Oh and by the way he has money, lots.


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## mastertech (Mar 14, 2011)

Hey Thanks Doc,couldnt sleep so figured I check out some posts.Its a shame you run into situations like that to have to shut the heat down but I couldnt live with myself knowing I couldve prevented a fatality.The laws are funny sometime but Ive heard of people being charged with negligence for allowing systems to stay on line when they were a definite health hazard!


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## mastertech (Mar 14, 2011)

*Hey gang whats your opinion.*

Theres a job going on and its funny because they ask for pros to not only do the job but make sure its done right ! The job has very limited access and theres not a lot of options with equipment as well.Due to how everything is set up makes it even a little tougher.Its upgrading split systems to 410a due to hail damage.This is a total upgrade changeout for both O.D.and indoor units ranging from 11/2 to 21/2 ton units with elec strips. The indoor is a complete tearout of the soffit and reframing to accomodate the units.When it comes down to it theres 2 2x4s thats used to anchor the air handler and 8ft long and 221/2 wide..These are plenty secure enough to handle this application with no problems.They have some young guy in there saying a lot of trash to the owners and its coming back to me.Hes mad because his family didnt get the job.Now after we got 4 done they want me to basically overkill on remaining 6 units.I know that its adequate support hell I can do pull ups on the thing and no problems at all.Do you think I ought to pacify the people just because or suggest the young little whippersnapper not get invovled or what? its not a lot of cost involved but a little bit of extra time as well tho that wasnt put into the bid.Anyway I like happy people but dont like to work for free either.:no:


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## hvaclover (Oct 2, 2008)

1mastertech said:


> Is That right? wow thats crazy,the people will hold you accountable for what...saving there life! Ive never heard of that before.Ive been taught that if theres a code violation or a problem that can be life or death is to disable it.You are the last person there and if something did happen you could be held liable for negligence for not shutting it down!WOW I guess theres different laws everywhere. Well what about your consience?:whistling2:


Allow me to elaborate..we shut off the furnace when we find CO. We document the shut off.

The customer turns the furnace back on. If we tell the city the HO is operating the furnace they tell us it's the customer's funeral.

The only exception is if the person is noticeably mentally disturbed or very old with senility.

Not my rules.


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## hvaclover (Oct 2, 2008)

Doc Holliday said:


> 1.) I agreee and applaude 1mastertech.
> 
> 2.) bull hell.
> 
> 3.) Mine will. We disable systems, call the city and they will come and confirm our findings of CO and turn off the gas to the home, quickly. If the homeowner/tenant doesn't like it, too bad. At least they are alive to complain.


Look dude keep civil will you?

I didn't give you any grief and would appreciate the same.

The city will not get involved here on a CO shut off and there is nothing going to change that.


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## MrBobb (Sep 8, 2011)

*Funny Story*: So I moved into this, not-so-great neighborhood, set my thermostat timer to go off just before waking up. Next morning, I hear this BANG, and again BANG noise and I go, damn I knew this neighborhood was kinda %&#%^. Not until later did I find out the wall furnace is the one doing the banging.

*Not so Funny Story*: So today finally I had someone in to look at the thing and the exchanger is cracked! So I was breathing CO for 5 months and is taking me 10 minutes to post this. Kidding. Damn heater.


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