Navien CH180 2 second burn on/off

[Jac04]

^^
There are actually 2 adjustments on the unit. There is a 3rd stage MIN and a 3rd stage MAX to adjust. It is all outlined in the manual. If you know what you're doing, make a u-tube manometer and do it yourself. You will probably be able to get the unit "dialed in" better than most 'professionals' (because it seems like most professionals aren't that familiar with these Navien boilers.)

However, BEFORE you make any adjustments on the unit, make 100% sure that the gas supply pressure is within spec. Don't just look at static pressure with the unit not firing, watch dynamic pressure as the unit fires. Using a u-tube manometer makes this easy, as a digital unit doesn't really let you see what's going on quick enough. Mine looked good static, but the original 2-stage regulator could not keep up with required gas supply when the unit fired.

After getting my gas supply issues taken care of, my unit seems to run quite nicely, BUT....
Every now & then, only when firing for heat, the unit will ignite, and as it ramps up it will loose flame, fire again and then stay firing. It's weird. My max firing rate is set for 35%, maybe that has something to do with it. It's almost like the fan overshoots the max firing rate, causing it to go lean and flame out.

Here's some other interesting facts, according to the Operation Flow Chart in the Service Manual:
You need flame-out within 10 seconds for 3 straight times to give you the 003E Ignition Failure error.
You need to loose flame 20 straight times during normal burner operation to get the 012E Flame Loss error code.

 

[Stephen C]

This is not a problem with the flame sensor - the sensor is working fine. Which is why cleaning it does not help.

This is a problem with the gas regulator adjustment.

If you google the service manual for this boiler you will see that you need to adjust the regulator by turning the screw accessible from the bottom of the unit in the right front corner.

You need a manometer and some 1/8" tee and plastic tubing to insert the manometer into the boiler to do the adjustment.

Getting this right will solve all the terrible "jet engine" sounds that people report.

But it does not always solve the 12e error problem.

If you still have this problem you need to turn the gas regulator screw another half a turn clockwise - assuming you did the calibration as directed.

 

[Sponsor]

 

[Stephen C]

^^
There are actually 2 adjustments on the unit. There is a 3rd stage MIN and a 3rd stage MAX to adjust. It is all outlined in the manual. If you know what you're doing, make a u-tube manometer and do it yourself. You will probably be able to get the unit "dialed in" better than most 'professionals' (because it seems like most professionals aren't that familiar with these Navien boilers.)

However, BEFORE you make any adjustments on the unit, make 100% sure that the gas supply pressure is within spec. Don't just look at static pressure with the unit not firing, watch dynamic pressure as the unit fires. Using a u-tube manometer makes this easy, as a digital unit doesn't really let you see what's going on quick enough. Mine looked good static, but the original 2-stage regulator could not keep up with required gas supply when the unit fired.

After getting my gas supply issues taken care of, my unit seems to run quite nicely, BUT....
Every now & then, only when firing for heat, the unit will ignite, and as it ramps up it will loose flame, fire again and then stay firing. It's weird. My max firing rate is set for 35%, maybe that has something to do with it. It's almost like the fan overshoots the max firing rate, causing it to go lean and flame out.

Here's some other interesting facts, according to the Operation Flow Chart in the Service Manual:
You need flame-out within 10 seconds for 3 straight times to give you the 003E Ignition Failure error.
You need to loose flame 20 straight times during normal burner operation to get the 012E Flame Loss error code.

 

[Stephen C]

Last year it was constant short cycling for a couple of months . Then power off for 10 min. . No other changes or adjustment . Power up and the problem was gone for months . That sounds like processor issue to me .
This year , it has a new dedicated ac outlet . No service or adjustment done to boiler and it has 3 months with only occasional single short cycles .

 

[Neil C]

Does anyone have any further information on this problem? I have been experiencing the exact same problems with my NP-240a for over a year now and the problem is getting worse. It has worked fine for 2 years so far, and now the problem happens almost every morning during the second shower. I've noticed that turning the water on full-hot, or another tap make it work and seems to suggest the flow sensor, but when I watch the flame, the greater flow-rate causes additional flame modulation to come on. At low flow, it looks as if the flame blows out as the exhaust fan ramps up. Could it be the air senor and how would you test?

 

[Birra]

The Naviens use a flame rod, to sense burner operation.
Error code 12 means flame loss. This would be due to improper sensing because of a flame rod issue or grounding, or loss of gas supply or improper pressure feeding the unit
Check the obvious, like tank fill level and confirm the tank is large enough to feed required capacity of all appliances.
The #800 number for navien is posted all over, consider calling their tech line for assistance.

I've had the Error Code 12 (flameloss) on my unit and I believe that I have found the solution for it. Check that the siphon is properly filled. There is a small valve that allows you to do this. Refer to page 28 of the installation manual (condensate Drain & Cleaning). I was having trouble for months, and decided to go step by step through the setup to see if anything was incorrect. The only thing I found was that the siphon was dry. I refilled it and it has been running solid since. I am pretty unhappy with my installer for missing this step.

 

[Keitho991]

Does anybody have any results to post concerning this problem / repairs?
I have a boiler doing the same E012 thing and Navien tech support says, after performing his checks, the boiler is working fine.
WTH? It is not!

 

[Jac04]

^ What checks were performed? Have you had your dynamic gas supply pressures checked? These units are VERY sensitive to gas pressure. That's where I would start.

 

[Stephen C]

I had tech check pressure with Navien on the phone . No problems found . My tech asked question about start up problem and Navien techs change the subject . I have a new issue which should be fixed with a flush .
The original problem is worse than ever . New flame rod made no difference . I change that every year .

If the unit is cold , It starts . If it was running 10 min ago , it will cycle on / off and not restart . I think the flame rod is not looking for flame . It is actually looking for a rapid change . If the combustion area is already hot , the the rod does not see enough change to recognize that the new flame started.

 

[Dana]

I had tech check pressure with Navien on the phone . No problems found . My tech asked question about start up problem and Navien techs change the subject . I have a new issue which should be fixed with a flush .
The original problem is worse than ever . New flame rod made no difference . I change that every year .

If the unit is cold , It starts . If it was running 10 min ago , it will cycle on / off and not restart . I think the flame rod is not looking for flame . It is actually looking for a rapid change . If the combustion area is already hot , the the rod does not see enough change to recognize that the new flame started.

The temperature of a natural gas flame is north of 1000 C. I don't care how long the thing has been off, it's still a HUGE and rapid change in temperature when it re=strikes, even if it's only been off for a few seconds.