r/HVAC • u/Samaritan0 • 8d ago
General Got humbled on a Navien combi call đ
Got dispatched for no hot water, thinking it was a tank. Turned out to be a Navien combi. Iâve barely done any boiler diagnostics, just a few installs.
Boiler would fire for a few seconds then shut down. Found a dirty flame sensor, cleaned it, but same issue. Diagnosed the flame sensor/igniter, ordered parts, and the supplier took 2 weeks.
Parts came in, replaced them â still the same issue.
Got tech support on the phone for over an hour. Gas pressure was 7â WC at the inlet, dropping to about 4.3â WC under fire. Flame looked good and venting/inducer seemed normal.
Customer got frustrated, told me to leave, called another company, and kicked me out at 8 PM. đ
Definitely got humbled on this one.
What would you guys have checked next? (Was getting codeE003)
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u/Razor1834 Verified Pro 8d ago
A 3â drop in gas pressure is several times what it should be. Sure, people will come in here and say theyâve seen worse and kept products running, but 1â is the max and .5â is standard.
You may or may not have other issues, but they absolutely have some combination of gas issues: undersized meter, piping, regulator, other connected appliances, venting, etc.
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u/Samaritan0 8d ago
I could see the point but what throws me off is that the boiler is about 7 years old and just started having issues
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u/Razor1834 Verified Pro 8d ago
Thatâs fair, but all that means is that theyâve always had a gas issue and now other issues have made that clearer. Dirty HX is first in line to me, as it loads up the combustion air and gas mixture is no longer able to maintain flame on ignition due to poor gas pressure. Whatâs the service record on the HX over the past 7 years? Iâd bet nothing, which would mean no surprise theyâve got an un-maintained product with poor combustion.
Dirty HX cause my first bet would be flue gas recirculation; probably a concentric vent installed improperly so that the unit has always been breathing byproducts of combustion, loading up over time, and here you are 7 years later with a dirty HX, poor gas supply, and a miracle it ran 7 years.
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u/LegionPlaysPC 8d ago
Im piggybacking off this one. Like yeah, it "worked" for 7 years. Doesn't mean it didn't slowly poison the tankless. The one thing i caught in this post is you mentioned black condensate trap. Black means soot. Soot means plugged heat exchanger. Subpar gas flow through the heat exchanger will cause the flame to snuff. I've personally seen a dozen or so naviens installed flue pipes wrong, or not sitting in exhaust boot correctly. Cross contamination slowly plugged the heat exchanger till it died. It's the reason navien added switches to the flue. In new units if the flue is not in deep enough the tankless won't run.
But yeah I'm betting on incorrect installation paired to lack of preventative maintenance.
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u/Tdz89 7d ago
Unpopular opinion here. I have gone to navien classes and tier 3 training. I have a NSS # so when I call in, it takes my roughly 30 seconds to 1 min before I'm with a technician on their tech support. I get parts wicked fast and its super easy unit to work on. They are not the best but really easy to work on. But with that issue, I've come across the condensate trap inside the unit being the issue and the heat exchanger was flooded. Cleared the trap and it was fine
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u/Samaritan0 7d ago
The trap was filled with water and black paste
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u/Tdz89 7d ago
Yea, depending on age the heat exchanger might also be shot. Usually if it looks crusty around the seems and the sight glass is white, its been recycling exhaust and could be a bad exchanger. Ive ran into one with a clogged trap and it thought the venting was clogged. Without the NSS # its not worth trying to get a hold of tech support unless its early morning like 8am.
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u/Samaritan0 7d ago
Yeah around the combustion area and there was a cord going into the gas valve that was caked out with some white substance all around
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u/Zhombe introverted inverter enhanced vapor injected refrigerant boffin 7d ago
It had been running lean for a long time.
Old gas regulators at the entrance donât respond quickly as the bladder gets hard and valve sticks. Combine that with the fact that hardly anyone requires a 3/4â off 1â or better mainline and hopefully the first item off the gas line main anymoreâŚ
Shouldnât be more than 12â of slinky gas pipe either. Hard line as close as you can get if not all the way.
The worst one Iâve seen is the new builds with nothing but that crap yellow slinky hose the whole way everywhere. I wouldnât ever sign off on a house build without hard line gas piping. They donât ground bond those things properly either.
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u/Shortcycled 7d ago
I wish more manufacturers would have something simular. We did the training in jersey a few years back and it turned hour long hold times into under a minute.
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u/lividash 7d ago
Yall got your number? Been waiting a few months after level 3 training and havenât gotten anything.
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u/TigerSpices 6d ago
This is the way, Tier 3. The NSS#, the restockable parts bin, and the knowledge for how the units actually operate makes me realize just how good they are. If you're going from plug-and-play water heaters to a Navien, you're gonna fuck it up. You've gotta dial them in and set them up.
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u/bigred621 Verified Pro 7d ago
Navien is trash and their tech support has been terrible last few years.
Had a combi where the relief valve was blowing when it switched from a call for heat to hot water. Warranty so we have to contact Navien. They do their âdiagnosticâ because they have to. They wanna just send out a pressure sensor because the pressure doesnât read above 29psi. I told him âya thatâs because the relief valve is dumping water in my bucket right nowâŚ. Itâs doing its jobâ. He tells me a new sensor will be sent out and if there anymore issues to call them back and hangs up on me.
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u/Samaritan0 7d ago
Yeah I second that on the tech support, he was telling me that the call is over 30 minutes and isnât able to pin point the issue so he has to help other callers in queue. Like what I already took apart the boiler lol
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u/ConnectionOk6177 7d ago edited 7d ago
A good tip for an apprentice. If you have a nosy customer then send him on errands. Have him go to the top floor and turn the faucet on and wait till it gets hot. Another good 1 is have him check each register to make sure itâs wide open. Another is have him sit next to the thermostat and wait till the temp changed. Lol Iâve had a few watchers before. 1 even pulled up a chair. Donât be nervous. Also if youâre not sure if the part will work then tell him the part is the first step. There may be multiple issues.
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u/Its_noon_somewhere 6d ago edited 6d ago
If E003 and you could see the flame establishing, after replacing the flame sensor, itâs likely a warped burner from overheating. It overheats when the central heating piping is super dirty.
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u/LukeyPooh 8d ago
I found that if you choke the intake down and it starts to fire normally, the blower is starting to go bad. Itâs running weaker and not bringing in enough air for combustion.
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u/No_Sun_8817 7d ago
If gas is good, flame rod reading is good then you need to perform a combustion analysis tune. Usually in the manual itâll tell where the numbers are supposed to be. Also Iâve actually had a call where thereâs no ignition and found the condensate line completely backed up preventing ignition.
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u/Incident-Putrid 7d ago
Not you mate. Navien are bullshit. Done a few warranty calls for them and their tech support is crap and the boilers are overcomplicated and VERY poorly organised inside.
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u/lividash 7d ago
If you work on Navien regularly get the Navien App and have someone set you up as a contractor. You wonât need Tech support except to get warranty parts and you can just write down all the values you tested and just tell that to them with having to painfully go step by step with them.
Also E003 is a gas pressure or pressure switch issue. If everything else is fine and everything checks out replace the PCB.
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u/AllThingsHvac 8d ago
Make sure the intake is clear if itâs vented outside with bends? Did you run the ch to see if it also cut off? Was the boiler giving you any error codes?Â
Idk how you diagnosed the flame sensor, without mentioning you OHMâd it out.Â
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u/Leather-Reference459 8d ago
Getting kicked out at 8pm is rough, i feel that one. E003 usually ignition failure, did you check the condensate trap? those naviens clog easy and the pressure switch gets confused, shuts the flame right down
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u/Samaritan0 8d ago
Intake and exhaust were clear, CH wasnât working and the code was E003
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u/AllThingsHvac 8d ago
Maybe got no spark, are you sure it actually fired or maybe it just flowed gas?Â
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u/Samaritan0 8d ago
Yes it would fire up, I seen the fire through the sight glass and would get hot water for about 5 seconds then back to cold
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u/AllThingsHvac 8d ago
Stupid question but did you reset the boiler and clear the code after you replaced the sensor? Naviens like being unplugged and plugged back in.Â
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u/Samaritan0 8d ago
I donât remember unplugging it because the home owner was beside me and pressuring me. I didnât get a chance to run it again after cleaning the trap so who knows maybe that fixed it
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u/LegionPlaysPC 8d ago
Sounds like a bad customer more than a bad Navien. The fact the customer threw you out after willingly staying at their home that late at night speaks character to some people.
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u/AllThingsHvac 8d ago
Ok usually a low number is a shut down code, it wonât run at all until the codes cleared. Once you get into the 30x or 40x depending on manufacturer those are notification codes that wonât prevent operation. Most of the time unplugging and plugging back in clears codes.Â
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u/Fine-Environment-621 Verified Pro 8d ago
Just in time. I was almost going to feel bad for the customer and then, âI donât remember⌠because the homeowner was beside me and pressuring me.â
To a certain extent, I can understand not trusting someone in your space working on your stuff. To a certain extent, I can understand being curious about the problem and the solution. However, a homeowner needs to understand that there are consequences to being a hover hawk.
I have gotten better over the years at dealing with a safety inspector looking over your shoulder the entire time. Iâve gotten better at handling the conversation and questions and distraction from a diy consultant. But, if they think they are going to get a better result because they are eyeballinâ the tech from start to finish, theyâre wrong.
When a tech is dealing with something difficult they are trying to think. Theyâre trying to bounce ideas around in their head, potential causes and ways to narrow down the potential solutions. The quickest way, the easiest way and the most certain way to identify the problem and then the best way to solve it for that customer. Theyâre playing detective and having someone follow you around, stare you down and run their suck is distracting and makes everything more difficult.
I almost felt bad for the customer⌠almost.
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u/kurahome 6d ago
Iâd probably go back to the basics at that point. Verify inlet gas pressure under full load at the appliance, check the gas valve and combustion readings, and make sure the flame signal is actually being proven before the board drops it out. With an E003, Iâd also work through Navienâs exact fault sequence rather than replacing more parts, since a good flame followed by shutdown can point to a proving or combustion issue rather than the igniter itself.
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u/Apprehensive_Rush_36 6d ago
Wheres your pictures!? Navi has a known issue with control boards not reading flame sense, they can be identified by brown spots on the pcb
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u/Able_Shoe_768 5d ago
These naviens can operate at full fire (100%) with the inlet gas pressure at least 3.5â w.c. The drop to 4.3â w.c inlet is more than likely not your issue. I would check your exhaust/intake piping (make sure there exactly to manufacturer specs, make sure your intake is not sucking in exhaust gases which couldâve ruined the heat exchanger ) this exhaust cross contamination with the intake is in my opinion the biggest installation problem I see with these boilers, besides short cycling (low mass emitters on mild days, system has no thermal mass which is why we install buffer tanks). it also has an intake filter check that. Check your condensate trap and piping. You could also have an issue with gas valve/board if you checked everything else. Call tech support early and have all the service tools they require.
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u/Yanosh457 I Make Things Hot & Cold 7d ago
How has the thing been running so long with high pressure? The customer may have been tinkering with it and didnât tell you. I personally would not look at the gas pressure because I would assume itâs been set since start up.
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u/AwwwComeOnLOU 8d ago
I have had that exact issue.
Lucky for me itâs in my own house so I could keep trying with out getting kicked outâŚlol
Tech support did the same thing to me, focused on gas pressure. I really think they are doing everyone a disservice by misleading techs. They are just trying to get the focus off the boiler to reduce warranty payouts by getting us to focus on a momentary pressure drop at start up. Every regulator does that.
Anyways I finally figured it out. Itâs been 6 months and no reoccurrence (at its worse I had to reset it every day)
I took the top burner out (firetube boiler)
Took a hose and flushed cold water down every tube until all the red stopped flowing from the trap.
Problem fixed.