Water Heater Makes a Banging Noise

[li2mi]

For the last week, my gas water heater has made a loud banging noise once it is done heating the water. It does it no matter how long it runs and it only bangs one time. It sounds the same as when your heating ducts expand/contract when there is any suction present.

The water heater is a Whirlpool and it is only 2 years old. Last Fall, the city came out and installed new water and sewage lines so my water was disconnected several times as the connected my line to the new piping and my gas was disconnected twice due to some error on their part. I also had a lengthy power outage this winter as well.

I do not hear any other noises from the water heater besides the normal sounds of it running its course. I also have not changed the temperature setting since it was installed so it is still set to the recommended temperature. The flu is connected to the chimney and there is a cover on the outside to keep any debris from blocking the chimney. There has also been no change in the water pressure that I have noticed. I have not flushed out the water heater (I am a new homeowner and was unaware that this should be done regularly so it is on my to-do list) since it was installed.

Any help or suggestions that you can offer would be greatly appreciated! I am handy but pretty close to clueless when it comes to the water heater so if you could dumb down your responses so that I have a chance to understand amd answer any clarifying questions you have, it would be wonderful!

Thanks in advance!

 

[journeyman]

It could be do to high pressure and the heat trap on the hot side of heater is slamming shut

 

[Caduceus]

Thanks for the many details. More questions may need to be asked to help you since a problem like this is tricky to diagnose at your home and even more difficult over the internet, so please bear with us.
A new problem on a new tank usually indicated something has changed recently, so let's start there...new water mains could affect pressure and introduce additional sediment to the tank as well as the natural build up from normal use.
Flushing your tank is a good first step. It will require you to shut down and then relight your gas water heater so become familiar with the process as it shows in your owner's manual and on the cover of the tank. You need to shut off the tank to avoid scalding and other actions that could harm your tank.
There are a few items that may be part of your plumbing system that we need to know about. I'll attach pictures to help with identification and you can let us know if they are there. If your water meter is in your home you might have a pressure regulator and/or a backflow device nearby. Since the tank is newer we also hope that there is a thermal expansion tank that was installed with the tank.
A question that will come up often on the forum is "what's your water pressure?"
Gauges are available at home improvement stores and hardware stores that screw onto a hose connection. (A valuable tool we would use at your home for any service call.) A gauge that goes from 0 to 200 psi should cover all possible pressures.
Since you said you're pretty handy, flushing the tank and checking the pressure shouldn't be too hard, but don't be afraid to ask for help if needed. You may get a variety of opinions as to how to solve the issue, but there could also be various reasons why it has started.

Alan sent a message to me last night about this problem and I didn't get it until this morning as I like my breaks from technology (this is my 'weekend'). That's why I referred you to this forum. If I'm not available there are a number of professionals that can help you. I'll be on my daughter's school field trip to the zoo tomorrow and orchestra recitals tonight, but I'll try to keep tabs on the thread.
-Scott

 

[li2mi]

It could be do to high pressure and the heat trap on the hot side of heater is slamming shut

Thank you for your response! I hadn't seen this as a possible problem in any of my research but it certainly sounds like it could be the issue. Could you direct me on how to check to see if this is what is causing the noise? Thank you!

 

[li2mi]

Thanks for the many details. More questions may need to be asked to help you since a problem like this is tricky to diagnose at your home and even more difficult over the internet, so please bear with us.
A new problem on a new tank usually indicated something has changed recently, so let's start there...new water mains could affect pressure and introduce additional sediment to the tank as well as the natural build up from normal use.
Flushing your tank is a good first step. It will require you to shut down and then relight your gas water heater so become familiar with the process as it shows in your owner's manual and on the cover of the tank. You need to shut off the tank to avoid scalding and other actions that could harm your tank.
There are a few items that may be part of your plumbing system that we need to know about. I'll attach pictures to help with identification and you can let us know if they are there. If your water meter is in your home you might have a pressure regulator and/or a backflow device nearby. Since the tank is newer we also hope that there is a thermal expansion tank that was installed with the tank.
A question that will come up often on the forum is "what's your water pressure?"
Gauges are available at home improvement stores and hardware stores that screw onto a hose connection. (A valuable tool we would use at your home for any service call.) A gauge that goes from 0 to 200 psi should cover all possible pressures.
Since you said you're pretty handy, flushing the tank and checking the pressure shouldn't be too hard, but don't be afraid to ask for help if needed. You may get a variety of opinions as to how to solve the issue, but there could also be various reasons why it has started.

Alan sent a message to me last night about this problem and I didn't get it until this morning as I like my breaks from technology (this is my 'weekend'). That's why I referred you to this forum. If I'm not available there are a number of professionals that can help you. I'll be on my daughter's school field trip to the zoo tomorrow and orchestra recitals tonight, but I'll try to keep tabs on the thread.
-Scott

Scott thank you so much! Alan and I go way back and he is always trying to help me when I actually have my 'damsel in distress' moments! Lol

There is not an expansion tank on the water heater and looking at the water meter (which is inside my house), I am not seeing anything that looks like a pressure regulator or backflow device. I can definitely head to the hardware store for the pressure gauge though so that I can start there. I took some photos to add here so that you can see what I am working with in case I missed something that you asked me to look for.

 

[li2mi]

Here are the photos

 

[IFIXH20]

Can you post a couple of close-up pictures of the draft hood / baffle area. The noise could be coming from your baffle not seated properly. You also need a drip leg on the gas line.

 

[journeyman]

That vent looks to be laying flat or level it should have a little pitch to allow the exhaust gases to escape. If you live in an earthquake zone you should install earthquake straps. And it would be a good idea to get that old gate valve replaced. It has calcium build up around it

 

[li2mi]

Sorry, ya'll are gonna have to be more specific. I don't know what the parts and pieces are. Draft hood/baffle area is what? A drip leg? Which vent appears to be lying flat? Old gate valve? I have no idea what any of these are.

I do not live in an earthquake zone.

 

[li2mi]

Do these help? I think this is what you were asking for.

 

[li2mi]

That vent looks to be laying flat or level it should have a little pitch to allow the exhaust gases to escape. If you live in an earthquake zone you should install earthquake straps. And it would be a good idea to get that old gate valve replaced. It has calcium build up around it

I see what you mean about the calcium buildup. It also let loose a couple drops of water when I ran my hand along it.

 

[li2mi]

Can you post a couple of close-up pictures of the draft hood / baffle area. The noise could be coming from your baffle not seated properly. You also need a drip leg on the gas line.

I figured out what the draft hood/baffle area is! Lol sorry! I am a moron when it comes to this stuff.

 

[havasu]

Is your draft hood close or touching your inlet and outlet pipes, or is it just the angle of the picture?

 

[li2mi]

Is your draft hood close or touching your inlet and outlet pipes, or is it just the angle of the picture?

It is just the angle of the picture.

 

[li2mi]

Thank you guys for all of your help. It turns out that it is the Flue Baffle expanding just enough to knock against the inside and cause the banging sound. Nothing I can really do about that except hope that it stops or replace a 2 year old water heater simply because it makes noise. Lol I will deal with the noise.

 

[IFIXH20]

Thank you guys for all of your help. It turns out that it is the Flue Baffle expanding just enough to knock against the inside and cause the banging sound. Nothing I can really do about that except hope that it stops or replace a 2 year old water heater simply because it makes noise. Lol I will deal with the noise.

Li2mi, You should have a professional out to check your water heater. The baffle noise could be caused by the water heater burning too hot (gas, burner, control or flue issue). If it is just simply a loose baffle the baffle can be bent a little to fit snug. Have the plumber check for any code volations (like the drip leg) and repair the leak on the cold water line at the water heater.

 

[li2mi]

Li2mi, You should have a professional out to check your water heater. The baffle noise could be caused by the water heater burning too hot (gas, burner, control or flue issue). If it is just simply a loose baffle the baffle can be bent a little to fit snug. Have the plumber check for any code volations (like the drip leg) and repair the leak on the cold water line at the water heater.

I already have. That is how I found out what the actual problem is.

 

[Davidcoleman]

well I also have a similar problem.. my electric heater also have some noise sometimes. Its actually a pool water heater and I am so much worried about that noise. Its don't make noise all time but sometimes when the heater runs for 30 to 40 minutes then it starts making noise.