Navien Tankless 240 A Making Pop sound from exhaust

[whatchawant17]

I had a Navien NPE 240a installed in my house 3 months ago. For the most part it works great. I had one instance where I got an ignition failure error, but I hit the reset button and haven't gotten it since.

However, in the last week I became aware of a loud pop sound occurring that sounds like compressed air shooting out of the exhaust pipe. Similar to the sound of one of those automatic tennis ball shooters. I wouldn't say it sounds like an explosion but it's loud enough that when standing outside near the exhaust pipe it startled me.

I've heard it about 4-5 times total in the last week, although I'm guessing it occurs a couple times a day since I'm not always here.

I turned the machine off, unplugged it and opened the cover to see if the intake air filter was clogged. Nope. Nothing else looked damaged to my eye.

When I replaced the cover (I didn't remove or touch anything inside, just looked) and turned the machine back on, it made the humming noise I usually hear when it runs, the clicks of valves opening, and a few seconds after start up it made the pop sound, which is quieter inside the house than outside. I also was able to see the unit this time and it visibly shook on the wall mount.

Another time I was near the unit when I heard the pop it occurred about a second or 2 after the re circulation cycle went on. So I heard it hum like it does for Recirc, then 1, 2, pop.

This doesn't occur probably 90% of the time that the unit runs or recircs. Vent outside is completely clear.

I called my installer and unfortunately he changed jobs and no longer does service work.

While I find someone else to get in and take a look I wanted to see if anyone else has come across this issue before.

I've provided a picture of the unit for reference. Exhaust vents to the side of the house and like I said I never heard the pop for the first 3 months of using the unit. Nothing else has changed in my house that would affect it either.

Thanks for any information.

 

[jeffmattero76]

My non-expert guess is that a little gas is building up inside the unit before it ignites.

I am not sure about a Navien, but, on my gas furnace, I had a similar sound to what you are describing. On the furnace, it was due to a clogged flame spreader. The gas would ignite in burner tube #1, and the flame spreader would take the flame horizontally across to burners 2 and 3. My flame spreader was clogged with a spider web, or some other debris, so unignited gas would flow for a second and then build up enough to ignite. When it did ignite, I would hear that sound.

 

[whatchawant17]

My non-expert guess is that a little gas is building up inside the unit before it ignites.

I am not sure about a Navien, but, on my gas furnace, I had a similar sound to what you are describing. On the furnace, it was due to a clogged flame spreader. The gas would ignite in burner tube #1, and the flame spreader would take the flame horizontally across to burners 2 and 3. My flame spreader was clogged with a spider web, or some other debris, so unignited gas would flow for a second and then build up enough to ignite. When it did ignite, I would hear that sound.

Thanks for the reply! I had that thought as well. Maybe too much gas is let out after a failed attempt and then when it ignites. Poof. Ugh.

 

[jeffmattero76]

Like I said, I have no experience with a Navien. Can you get to the burners? Perhaps a pipe cleaner could get in and clean the burner and flame spreader holes. For cleaning a gas range, I have a set of needle files that will clean the holes is a range burner after a spill clogs them up. You can get those files at a welding or industrial gas supply company. Mine is a set of about 10 files, and the cost was less than $5.

 

[wood4d]

where is the recirc connection? this photo doesnt have recirc. there is a separate port for recirc.

 

[havasu]

Have you called tech support at Navien?

 

[whatchawant17]

Have you called tech support at Navien?

I did. All they said was unplug it and have someone service it.

 

[whatchawant17]

where is the recirc connection? this photo doesnt have recirc. there is a separate port for recirc.

I don't know to be honest. The recirc icon is lit up. That's as much as I can tell.

 

[whatchawant17]

where is the recirc connection? this photo doesnt have recirc. there is a separate port for recirc.

I think it's on internal recirc mode. Which if im understanding correctly doesn't use the external port.

 

[whatchawant17]

Like I said, I have no experience with a Navien. Can you get to the burners? Perhaps a pipe cleaner could get in and clean the burner and flame spreader holes. For cleaning a gas range, I have a set of needle files that will clean the holes is a range burner after a spill clogs them up. You can get those files at a welding or industrial gas supply company. Mine is a set of about 10 files, and the cost was less than $5.

To be honest I'm not comfortable attempting that on my own.

 

[havasu]

I know when I installed my Navien, I had a rep from the company paying real close attention to the natural gas input, worried that there was not enough gas pressure to run it. Then again, the factory is about 45 minutes from my house.

 

[whatchawant17]

I know when I installed my Navien, I had a rep from the company paying real close attention to the natural gas input, worried that there was not enough gas pressure to run it. Then again, the factory is about 45 minutes from my house.

I'll have whoever I can get in double check that. I wondered if my pressure could vary and maybe some reason it dropped although my furnace hasn't had any issues.

 

[RenewDave]

Wow, that’s a seriously rough install. Is that a 1/2 inch gas line? How long is the run? If the unit is starved for gas, you could have issues. Hire a real pro get him to check gas pressures with factory. And, what size room is that in? Could be a combustion air problem.

 

[whatchawant17]

Wow, that’s a seriously rough install. Is that a 1/2 inch gas line? How long is the run? If the unit is starved for gas, you could have issues. Hire a real pro get him to check gas pressures with factory. And, what size room is that in? Could be a combustion air problem.

I'll have to double check the gas line. Not sure. Room is small but has louvered door that opens to fairly large finished basement.

 

[breplum]

Look up on the Navien website, the "local" list for NSS (Navien Service Specialist) registered companies. They will have all the tools they need to diagnose and solve the issues.
Navien covers labor and parts for new installations, IF<, there are no problems with the installation, the servicing company will have the cost taken care of by Navien.

 

[whatchawant17]

Look up on the Navien website, the "local" list for NSS (Navien Service Specialist) registered companies. They will have all the tools they need to diagnose and solve the issues.
Navien covers labor and parts for new installations, IF<, there are no problems with the installation, the servicing company will have the cost taken care of by Navien.

Thanks! Looks like my furnace/AC company is on the list. Will get them in asap. Hopefully this is an easy diagnosis.

 

[Rickyman]

Thanks! Looks like my furnace/AC company is on the list. Will get them in asap. Hopefully this is an easy diagnosis.

Keep us posted

 

[whatchawant17]

Wow, that’s a seriously rough install. Is that a 1/2 inch gas line? How long is the run? If the unit is starved for gas, you could have issues. Hire a real pro get him to check gas pressures with factory. And, what size room is that in? Could be a combustion air problem.

It's 3/4 inch on the rigid pipe at the bottom, the flex part above is 1/2. That connects from the main line. One part goes to furnace and this to water heater. I have someone coming to look tomorrow. Just curious why do you feel it's a rough install?

 

[RenewDave]

Well, I don’t like to bad mouth other guys work......ok, yes I do. That gas line is not correct. A 3/4 line, we don’t know the overall length, serving a furnace(approx 125 k btu) and now a tankless (potentially 199k btu) is not adequate for a number of reasons. If you’re going to convert to tankless and need to run a pvc exhaust, hell, run a fresh air intake from the outside also(takes the combustion air issue off the table). You need to service your tankless, but your installers didn’t put a service kit in during installation. It’s a 100 dollar part that you will pay 300 for a service guy to install. Our code does not allow pex to be installed within 18 inches of a water heater, so that’s wonky to me. I can’t see where your t&p runs to.
We run a tight ship and we aren’t cheap. We take pride in our work our installs are done like I am going to come through and pick it apart, every one. So other guys can’t.
I’m not saying it won’t work, new cars work with bad gas and dirty air filters, but when they error code, it will cost you more in the long run than having a first rate install to begin with. And when a guy does a first class job, chances are he’s the one servicing it and doesn’t have to worry about a substandard install.

 

[whatchawant17]

Well, I don’t like to bad mouth other guys work......ok, yes I do. That gas line is not correct. A 3/4 line, we don’t know the overall length, serving a furnace(approx 125 k btu) and now a tankless (potentially 199k btu) is not adequate for a number of reasons. If you’re going to convert to tankless and need to run a pvc exhaust, hell, run a fresh air intake from the outside also(takes the combustion air issue off the table). You need to service your tankless, but your installers didn’t put a service kit in during installation. It’s a 100 dollar part that you will pay 300 for a service guy to install. Our code does not allow pex to be installed within 18 inches of a water heater, so that’s wonky to me. I can’t see where your t&p runs to.
We run a tight ship and we aren’t cheap. We take pride in our work our installs are done like I am going to come through and pick it apart, every one. So other guys can’t.
I’m not saying it won’t work, new cars work with bad gas and dirty air filters, but when they error code, it will cost you more in the long run than having a first rate install to begin with. And when a guy does a first class job, chances are he’s the one servicing it and doesn’t have to worry about a substandard install.

Ugh. Thanks for the info. The guy was highly rated on all the sites I could find and I wouldn't say it was cheap. It's hard to know who does a bad job until after they do it, it seems. I'll see what the next company says and address these issues if they don't. I try to do my research well but everytime there's something I'm not happy about. Good work is hard to find.