Navien Tankless 240 A Making Pop sound from exhaust
- Thread starter whatchawant17
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whatchawant17
Active Member
I appreciate it. Nothing really surprises me at this point but it's always disappointing when I find out.
whatchawant17
Active Member
An update for those interested. I had a service call this morning (with one of the bigger companies in my area who also did my furnace and central air last year with no problems). They ran through all the tests Navien support required and no error codes resulted nor did the pop occur while he was here after numerous demand attempts. Based on what they tested, and what i told them about it only occurring on the occasional cold start, they concluded that it could be a delayed ignition but that should result in a corresponding error code. Which hasn't happened. The service guy also checked the installation and found nothing wrong other than a few things he would've done different. But none of those things would result in the issue I'm having and it is safe to use. So that's where I'm at.
whatchawant17
Active Member
So it turns out I actually had too much pressure coming into the house. I called a new plumber, who went through all the diagnostics with Navien, tested it all and it was fine, no error codes. Then the last thing they wanted him to do was to test the gas pressure to which he replied that he did not have any tool to do that with in his truck. Mind you this is a huge company. He left, said it was fine and if I get an error code they'll come back and check that out.
So I didn't like that answer and called my gas company to check the pressure and the vent because I was concerned too much gas was being exhausted.
Turns out there was an excess of pressure and gas was indeed mixed with the CO exhaust. My pressure he said was somewhere around 10-12. He had to replace the main regulator and lowered it to a 7. After that the exhaust only read gas for a brief second upon starting up the unit and the CO level went from about 50ppm to 30ppm.
The guy from the gas co basically said he didn't know if that would stop my issue but it's likely the pressure was so high that the unit couldn't burn the amount of gas coming through fast enough and that definitely could lead to gas build up making the pop sound.
I'm calling now to to try and get my service diagnostic fee back from from the company that didn't check the pressure at all.
whatchawant17
Active Member
So it turns out I actually had too much pressure coming into the house. I called a new plumber, who went through all the diagnostics with Navien, tested it all and it was fine, no error codes. Then the last thing they wanted him to do was to test the gas pressure to which he replied that he did not have any tool to do that with in his truck. Mind you this is a huge company. He left, said it was fine and if I get an error code they'll come back and check that out.
So I didn't like that answer and called my gas company to check the pressure and the vent because I was concerned too much gas was being exhausted.
Turns out there was an excess of pressure and gas was indeed mixed with the CO exhaust. My pressure he said was somewhere around 10-12. He had to replace the main regulator and lowered it to a 7. After that the exhaust only read gas for a brief second upon starting up the unit and the CO level went from about 50ppm to 30ppm.
The guy from the gas co basically said he didn't know if that would stop my issue but it's likely the pressure was so high that the unit couldn't burn the amount of gas coming through fast enough and that definitely could lead to gas build up making the pop sound.
I'm calling now to to try and get my service diagnostic fee back from from the company that didn't check the pressure at all.
wood4d
Well-Known Member
My 2 cents..... if you dont install a service kit (ie a way to clean the coils) when it clogs you have to retrofit it. if you do a gas calculation on the house you will find that you are starving both units for gas. They say you can run a navien on a 1/2" line for 20' but you have a 199k btu unit. Low gas pressure isnt good for any of your mechanical equipment. The louvered door probably doesnt meet any up to date codes and its not that hard to get a 2" intake outside. Also in nj we have to run a 1" cold water line if its pex for anything over 2 1/2 baths. 3/4 copper is fine but 3/4 pex is small. There is no t&p valve on the unit because it comes with the service kit. (even though i dont really think a tankless unit really needs one) I put in lots of these units and like renewDave said these things are computerized water heaters and you need to be picky when you install them. As far as my recirc comments go, you bought a 240a when you could have gotten a 240e for a few hundred bucks less that does the same thing.
wood4d
Well-Known Member
of course i typed all that before your post came up but all you need is a manometer to check the gas pressure and the port is built into the unit
whatchawant17
Active Member
Thanks for the advice, I'll definitely look into it more. I hate that I have to become the "expert" every time the expert I hire is supposed to know what's going on.
whatchawant17
Active Member
No worries, the more info I have the better. I can't believe a plumber from a huge service company doesn't carry around a manometer. I would think that is a standard thing to check in almost any situation involving gas appliances malfunctioning.
I'm not sure why the installer didn't mention the service kit when he put it in, sounds like it should be standard with an install. The company that was here today didn't mention it either even though he claimed to have put 30 units in and wants to put one in his house soon.
Like I said in another reply, it's so hard to find good work even when doing as much research on contractors as possible. No matter who is in here there's always something that gets missed. And I'm not saying this to brag or anything, but price is never a factor when I get work done. I always stress quality over finding someone cheap. It's just impossible to judge it seems.
I appreciate the feedback, thanks.
I live in a town of about 100k population. Lots of plumbers but I would say less than a half dozen that can actually do a full service on a tankless. Checking gas pressures and previous error codes is just part of a full service. Consumers beware, that’s the way it is anymore.
Those are service kits, you can also see the installer used pvc on t+p drain on the left. Right side pvc is condensation drain.
whatchawant17
Active Member
I googled it quick and I guess it does look like a service kit. I had no idea what I was looking for to be honest. Does my new pic help clarify? Appreciate the discussion from all.
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yes, that is the service kit
whatchawant17
Active Member
Well I'll chalk that up as a win. Thanks! I had no idea a service kit was a thing and that it could be optional.
whatchawant17
Active Member
If you don't mind me asking, I called back the company who came to check the unit, yet left without checking the gas pressure, because he said he didn't have a manometer on him. I thought that was weird, and I heard navien on the phone ask him to check as part of the diagnosis.
I explained how the gas co found a broken regulator outside and gas pressure of 12. He replaced the regulator and lowered it to 7 where he said it should be.
After he fixed that, less raw gas, almost zero, was coming from my navien exhaust and the CO level was lower as well indicating more efficient combustion. Which according to Gas co was normal as opposed to the high level of gas and higher CO level coming out of the exhaust prior.
I voiced my feedback to company who came to service but didn't check gas pressure anywhere in the unit.
Their plumbing dept said that the unit should regulate the pressure and changing the pressure outside shouldn't matter.
I said well if the unit regulator wasn't working or set correctly wouldn't that have been the issue that he would've discovered by checking gas pressure? They then talked to me in circles and said that if navien thought gas pressure was an issue their guy would've got a manometer from another team member. They also said not all their guys carry a manometer.
I actually called Navien back to put the Gas co's findings on my serial number record and they agreed that could have been the issue.
Anyway, it sounded like they're covering their ass for not being thorough so as to not give me my money back (which I hadn't actually ask for yet), or am I just nuts that they failed to do a complete check up?
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Any....and I say any serviceman for a tankless unit should not get a penny if they don’t have the tools required to service your unit. PERIOD. A manometer is a required tool. Most companies (tankless suppliers)will not start a service session without the plumber having the required tools.
When installing my Navien, a nanometer was a required tool to confirm you had the proper natural gas pressure.
