Navien CH180 combi Error 12e & 48e

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dalack

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Unit has been installed for a couple of years and no problems until now.
Now its giving me a 12E & 48e error codes
Checked gas pressure with manometer and pressures are up to spec at 12 and don't drop.
The unit will light and then go out repeatedly until it errors out but sometimes stays working for a while.
Replaced gas pressure switch, air pressure switch and flame rod assembly but still having the same problem.
Navien tech support hasn't been much help with this issue.

Thanks for your help
David
 

Jemal

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Been working on my earlier CR-180 with similar flame on / flame off behavior... takes maybe a dozen attempts to stay lit. Replaced flame rod and now lights a bit faster... sometimes! But now will fail and go cold and fluctuate DURING a shower! How? From installing a new flame-rod??

When you say gas pressure switch and air pressure switch, do you mean the "sensors" that look a bit like a hockey puck (Navien tech described them this way!)? These have a vacuum diaphragm and sense changes in pressure via two little hoses... That's where I am now after weeks of replacing things like the flow sensor, the main board, various little elbows and sensors from an upgrade kit for the earlier units. Mine came with my new house in 2009, but not really much use as it only heats water for our small guest quarters.

If I've learned anything about mine, I suggest at least checking the flow sensor... just take it out and clean it even. And make sure no animal or moths or birds have found a way into you venting!

Good luck!
Jemal
 

Rcb11

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I know this is an old thread, wondering if you guys got your units working and what it was? I am having very similar issues with a NR-180 A LP unit. Started out as 12E, I checked and cleaned the venting, then replaced the flame rod assy, then went to 003E, we can get it heat after resetting (sometimes), but is very intermittent, will try many times to light and then goes out, always takes 5 to 10 attempts to even get a flame the first time. (Always get good looking ignition on the flame rod through the site glass). Now this morning got a 48E code, which is the first time seeing this one. Going to have the gas pressure tested to see where it's at. We do have a Goodman forced air furnace that is also on the same gas (LP) feed, and never ever misses a beat. Thanks in Advance for any suggestions.
 

John Gayewski

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The condensate and exhaust/ vent system are all connected. Sometimes cleaning and checking the condensate drains does the trick.
 

Fitter30

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Theres a air filter just above the fan need to check it. Also check the lp tank regulator screen might also have a reg at the house. Screenshot_2022-01-22-16-11-34.png
 

Rcb11

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The condensate drain is good, can see water coming out. I also cleaned the air intake filter. We had the gas pressure tested at the unit, and it was acting kinda funny, both high readings and low, so we are replacing the 2nd stage regulator at the house, will see if that does the trick. Thanks,
 

John Gayewski

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Lp can act funny with the temperature.

Just because it's draining doesn't mean it's good.

Hope the regulator helps.
 

Rcb11

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Ok, I'll check the condensate again.

And yes it's been D*** COLD here lately -20 last night! LOL
 

Rcb11

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Hi Again,

Wanted to give an update: We got a new gas (propane) regulator installed and adjusted yesterday, and didn't change anything on the Navien. It still tries to fire, but fails most of the time, I can stand next to it and count the clunks from the main gas valve, 1,2,3,4,5 - up to 10, then throws the E03 code, then i power it down for about 30 seconds, then back up. Once out of 5 or 7 tries, it will get flame for about 3 seconds, then dies, and goes through the cycle again, then randomly it will fire up and heat normal for as long as we want, very intermittent, not sure what to think, any input is welcome, Thanks in advance.
 

John Gayewski

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Hi Again,

Wanted to give an update: We got a new gas (propane) regulator installed and adjusted yesterday, and didn't change anything on the Navien. It still tries to fire, but fails most of the time, I can stand next to it and count the clunks from the main gas valve, 1,2,3,4,5 - up to 10, then throws the E03 code, then i power it down for about 30 seconds, then back up. Once out of 5 or 7 tries, it will get flame for about 3 seconds, then dies, and goes through the cycle again, then randomly it will fire up and heat normal for as long as we want, very intermittent, not sure what to think, any input is welcome, Thanks in advance.
Is your propane tank above ground?
 

Bannerman

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LP stands for Liquid Propane. Propane supplied to appliances is gas vapour which means the liquid propane must evaporate to create sufficient gas vapour to supply the appliance(s).

Although liquid propane will boil at a low temperature, the heat needed to cause the liquid to evaporate is most often obtained from the surrounding air. The recent extremely low weather temperatures will result in LP to boil at a lower rate compared to when external temperatures are higher.

To provide a sufficient rate of evaporation, the tank must be large enough to provide adequate surface area for the liquid fuel to absorb sufficient heat from the surrounding air. When the outside temperature is lower, a greater quantity of liquid fuel will need to be in the tank.

The rate of evaporation is also dictated by the vapour pressure. When your Navien first ignites, it will consume fuel at the maximum rate (150,000 BTU) until the outgoing water reaches sufficient temperature for the flame rate to be modulated to a lower rate so as to maintain the desired temperature at the flow rate required at that time. When the Navien first fires, there will be a substantial drop in tank pressure before additional fuel will be evaporated. While the pressure may remain adequate after the regulator, there maybe too little liquid fuel being initially evaporated to keep pace with consumption, particularly during periods of extremely cold external temperatures.

Perhaps you experienced succesful operation while the outside temperature was not as extreme as it has been recently, or may be during the day while the sun was adding some warmth to the tank?
 
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Rcb11

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Hi guys, thanks, yes tank is above ground, also some more back story.

The Navien was installed about 10 years ago, and has ran with very little issues over the years, same tanks (2 - 500gal), same feed line to the house, etc. also we have a Goodman forced air furnace that is less than 10 feet away from the Navien, and that has ran all winter with zero issues, (even before the regulator change).

I’m thinking something with the main gas valve or gas manifold? Or one of the pressure switches (APS or GPS)? Also can the heat exchanger be taken apart and cleaned?
Thanks again.
 

Rcb11

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Hi guys, have an update, so one of the first things I did was replaced the flame rod assy. back last month, well for the sake of troubleshooting, I put the old one back in, and what do you know? it started firing up within 3-5 tries, every time, havent had any error codes for two weeks! So I got to looking at the new flame rod, and it ended up being the wrong part, I didn’t realize until I looked at it close, it was for a natural gas unit.

So i’m thinking the LP regulator was a problem initially causing erratic gas pressure, and my new (wrong) flame rod was causing a second problem. Anyway thanks for the input, we‘ll keep our fingers crossed it keeps working.
 
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