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rattling noise (gas furnace)

3268 Views 5 Replies 2 Participants Last post by  yuri
There is a rattling noise from inside the wall when one of our gas furnaces is running. Please note: I don't intend to do any DIY here. I am just wondering if folks think this is more of a HVAC issue and I should call a heating and air place, or my gas company.

I really just started noticing it getting worse in the past few weeks. But the issue is not new. We bought this home late last winter, and I recall hearing it a time or two then, as well. But I live in Carolinas, and we didn't have to run the heat often last year. And just really started using it for this season in past few days.

Here is the odd thing. The house has multiple gas furnaces. One in the crawlspace under the house (for 1st floor), one in the attic (above my master BR) for the second floor + third floor attic playroom, and one for an addition (way across the house).

So the thing is, I hear the rattling in the wall right behind my headboard in master BR....but only when the downstairs/crawlspace unit is running. Not the one up in the attic. If it was the reverse, would make more sense to me. Again, sounds like a rattling, starts slow, gets stronger and only happens when the furnace under the house is running. I am worried its a pipe or something loose. I have not gone under the house to see if its louder there. I can access the attic where the second story furnace is, and I can hear it loud/clear in there. But again....that's not the unit that is running. That's why I fear its some kind of gas line issue.

Is this a gas company thing to diagnose or a heating/HVAC place? Thanks,
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Do you have a heat pump? If so it may be the freon lines running thru the wall and you are getting a sound thru them. If so the freon level should be checked.

Either way call a HVAC place as the gas company only looks for leaks and takes care of the meter and regulator.
thanks for the reply, Yuri. I am going to sound very ignorant here...but I don't actually know. photos attached.

I have 3 electric units outside by the garage that we call "heat pumps" but I only ever notice these "heat pumps" running (fan turning) when the AC is on in summer. I have heard them called compressors too. there are 3 gas giants that I call furnaces/air handlers inside that seem to do all the heating (pilot light, etc); but again they may work with the exterior concert. not sure.

anyway, just for my understanding...I thought Freon was for cooling (only). or does it play a part year round?

appreciate the note


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Probably you have heat pumps as they are very popular in the Southern US. Get the model # off of one of the Carrier outdoor units and post it here and we can look it up or you can google it.

It uses the freon year round. A heat pump has a freon flow reversing valve so in heat it cools the outdoor coil (removes heat from outside ) and dumps it inside your house same as it dumps it outside in AC season.

You should have regular maintenance done on all your units. Freon level needs checking, flame sensors need cleaning plus a bunch of other checks.

May be a good idea to get the installer or a reputable Carrier dealer.

Gurgling freon noise usually means it is low on freon and that can damage it as well as drastically reduce it's heat output and drive up your fuel and elec bill.
"gurgling" is a good description of what I hear actually.

just to be safe I called the gas company. no safety issues that they detect. they think its likely something bumping/rubbing/shaking/rattling against the gas line somewhere and the noise is radiating up along the gasline. could be anywhere in the system...will be very hard to find....but I guess I will have to ask an HVAC tech to look. one culprit they said could in fact be a Freon line.

thanks for the note! take care.
Yur Welcome:wink2:
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