Navien CH210 LP exhaust CO levels upwards of 3000 ppm?

DonP152

This is a link to my original Rinnai / Navien post but it is dated and this is actually a separate issue. http://forum.heatinghelp.com/discussion/139259/rinnai-e110cp-explosive-ignition-and-low-heat#latest

For anyone following this thread, Navien did replace my original defective combi boiler after 12 error messages in 90 days with a new CH210 LP. It works. It's loud, very loud. I had to put in a domestic recirc loop with a timer to get hot water within a 2 minute window but we've learned to live with that.

Navien CH210 LP. Professionally installed by Paul Feeney & Sons who is now the Navien Tech representative. Jan-2013

My new issue is this: I had my burner tech in to do a tune up on my unit yesterday. His initial combustion analyzer test using the test hole inside the unit on the exhaust side got up to 3800 ppm of CO and was rising. He took the tester out as he did not want to ruin it with the high CO levels. Just for kicks he tested exhaust vent outside and got the same. Called Navien tech support and they said that we needed to a full high fire to test and walked us through it. Cover off, dip switch #1 flipped up. All hot water on. Ran for 5 minutes and ended up with a 340 ppm reading in the exhaust.
However, when unit went back to normal modulating cycle, CO ppm went right back up into the thousands. Called Paul Feeney (Navien technical representative) and he said "you're testing it wrong" so I explained how we tested it with his tech support, got the 340 ppm on high fire and he said "that's within range" and that everything was fine if it was under 400 ppm. When I asked him what would happen if I had a cracked exhaust pipe with a close to 4000 ppm CO level his response was "you don't have a cracked pipe, now... do you?"
I'm very leary of having such a high CO ppm during regular modulation. Another tech I spoke with said he's tested hundreds of modcom boilers and never seen CO that high.
Am I wrong to be concerned as Navien only tests CO levels at high fire?
Specs: static LP pressure 11.5, Direct vented with 3" PVC out the wall. Inlet air is over 8' away and is 3" PVC as well so there's no contamination. Screen is clean, Sediment cup has been emptied (and it was full of black gunk)
Navien's installation and homeowner manual made no mention of proper testing procedures so they sent me the attached testing procedure.
If, after this test I still have high CO ppm in normal modulation exhaust, should the unit be considered defective?
Many thanks for any input and help in advance.

icesailor

Where did the "black gunk" come from? Is it unburned fuel contaminants like soot? Is the HX plugged like a few WA furnaces I have seen with blocked secondary Heat Exchangers?

C3H8BURNS

I have a few questions
What elevation are you at?
What is the length of your vent intake and outlet and how many elbows in the run.
Does the units data plate say its for LP and if it was converted was it done correctly and was the manifold pressure checked?
Does the person testing the unit have a o2 sensor to check the flue gasses.
Just to confirm, after running the unit on high fire for 5-10 minutes does the co go high on lower flame, I ask because high co levels are more common when a 'cold' appliance fires up. reading should be done after the burner box has had a chance to heat up to 'normal' operating temp

Jamie Hall

While high CO levels -- though not that high -- are normal enough when the unit is cold, it isn't cold for very long! Minutes, if that. CO levels in the range you are seeing indicate something is very much amiss and are, in my humble opinion, quite dangerous.

DonP152

I'll try to answer as best I can.
Black gunk was in the sediment cup for the condensation pipe. We don't know where it came from nor what it is. I've spoken with a couple of other techs that install / maintain Navien and they said that this a normal for Navien units.
Exhaust pipe is 3" PVC. Runs up approx 8", elbows out the back wall, elbows up for approx 24" to get it above an ac compressor with a 90 degree elbow at top, so 3 total elbows.
Intake is 3" PVC and comes in from the left side of the unit with a run of approx 6' from the wall. (Looking at the unit, exhaust goes out the back wall and intake comes in from the left wall so they are not on the same wall.)
I am at sea level.
Unit does say LP on it and was installed by certified Navien tech who is now the official Navien tech rep so I would have to consider it ok.
Flue gas CO was 340 ppm at high fire, after 5 minutes warm up on high fire. As unit went back to regular lower modulation CO rates climbed up to 3800 ppm which is when he pulled the sensor out to avoid damaging it.
Navien tech support along with Navien tech representative who installed this both say that as long as it's under 400 ppm at high fire the high CO levels at lower fire/modulation are ok. That is what's bothering me. Knowing that I have close to 4000 ppm of CO during normal operation.
Navien wants us to test pressures using a manometer as per the attached pdf file. It would have been nice if they had mentioned that testing procedure when my tech was actually still here...

Many thanks.

icesailor

At some point, every oil burner I ever serviced, I checked the pump pressure for proper adjustment. I had all kinds of proper gauges.

When I started doing gas, I went out and bought myself a decent digital gas positive and negative gas pressure instrument.

How can you use a Digital Combustion Analyzer without knowing the gas pressure? To not use a pressure meter is like disconnecting the speedometer on your car and just guessing at your speed and how far you have traveled.

DonP152

Gas pressure was tested. Earlier post I said static gas pressure was 11.5. Navien wanted it adjusted up to 13 which is the absolute highest the boiler could take. We tested at 11.5 when we got the high CO reading which was from a digital analyzer.
Thanks

Paul48

The testing procedure they are talking about, is, if you can't get below that 400 ppm at high fire. They seem to feel that satisfying that one testing requirement is good enough.
My car only operates efficiently at 55 mph. Below that, it dumps the excess gas on the highway. Does that about cover it?

RobG

A little off topic but does anyone still use a slack tube manometer? On todays equipment I wouldn't trust a slack tube to get me within a .08 differential pressure. I mainly use my digital and use my magnehelic as my back up.

Zman

Over 3000 seems crazy high.
I know navien is disinterested, but do you have co2 or O2 readings.
Is there any chance you have a ng model running on lp? Maybe mislabeled? That would explain a lot.

Tim McElwain

I don't care what Navien tells you all that is bull. Something is definitely wrong when you get that high a CO reading at any time. We want to see less than 100 PPM CO at all times. The ANSI allowable 400 PPM is not what we shoot for.

Also telling you to jack the pressure up on an LP systems is also a violation. You are getting up into the area of lockup un the second stage regulator when you go past 12.5" W.C.

I would get that thing out of my house if I were you. Shut it off and do not use it, I would not want to read about you in the paper.

I would like to see what a complete set of readings looks like along with a draft reading.

Navien the same people that say you can run 1/2 inch pipe 24 feet without a pressure drop when running at 199,000 BTU's.

I guess I need to go back to school somewhere to learn all about this new equipment and the gas it burns and how all the fundamentals no longer apply.

Tim McElwain

Rob G I still use my "U" gauge on conventional gas equipment. I use the digital on all Mod/Con equipment and any equipment with negative pressure gas valves as the water manometer used on those will suck the water out of the manometer and it will go into the gas valve.

I also have a Dwyer Slant Gauge which I like for use on testing pressure switches.

Paul48

Remember.......Navien told another poster, that unburnt gas in the exhaust was normal. I guess you could pipe it over for your neighbor to use.

Ironman

Tim McElwain said:

I don't care what Navien tells you all that is bull. Something is definitely wrong when you get that high a CO reading at any time. We want to see less than 100 PPM CO at all times. The ANSI allowable 400 PPM is not what we shoot for.

Also telling you to jack the pressure up on an LP systems is also a violation. You are getting up into the area of lockup un the second stage regulator when you go past 12.5" W.C.

I would get that thing out of my house if I were you. Shut it off and do not use it, I would not want to read about you in the paper.

I would like to see what a complete set of readings looks like along with a draft reading.

"Navien the same people that say you can run 1/2 inch pipe 24 feet without a pressure drop when running at 199,000 BTU's.

I guess I need to go back to school somewhere to learn all about this new equipment and the gas it burns and how all the fundamentals no longer apply.

Maybe they mean you can run 199k btu's on a 24' x1/2" line when it's on a 2psi system.

And let's not forget about their magical manifold that turns 50k btu's into 120k on a high temp zone.

DonP152

Update: Got a hold of a Navien tech support guy who surprisingly agrees that the CO level is too high. Believes the air / gas ratio is off. I don't know how it could magically go from good to bad, but we will be testing again in the near future, adjusting and hopefully get the CO levels closer to 100 ppm which is what this tech support guy says is correct. I'll update as soon as we know.
Many thanks for the input and help thus far!

Gordy

Really so it depends which tech support personel answers the call as to what's exceptaple??

Zman

Tim McElwain said:

I don't care what Navien tells you all that is bull. Something is definitely wrong when you get that high a CO reading at any time. We want to see less than 100 PPM CO at all times. The ANSI allowable 400 PPM is not what we shoot for.

Also telling you to jack the pressure up on an LP systems is also a violation. You are getting up into the area of lockup un the second stage regulator when you go past 12.5" W.C.

I would get that thing out of my house if I were you. Shut it off and do not use it, I would not want to read about you in the paper.

I would like to see what a complete set of readings looks like along with a draft reading.

Navien the same people that say you can run 1/2 inch pipe 24 feet without a pressure drop when running at 199,000 BTU's.

I guess I need to go back to school somewhere to learn all about this new equipment and the gas it burns and how all the fundamentals no longer apply.

Tim is one of the most knowledgeable guys out there.
Be sure to get the complete readings the next time it is tested.
It really is not just about CO and draft. Those are just part of it.

DonP152

Thanks to you both. I have two techs that I trust and are very skeptical of Navien. If either one is uncomfortable with tests, adjustments and results we'll pony up for a new unit. One that won't be a Navien or a Rinnai for sure.
I'll also forward this forum posting to them as well. Again, many thanks for your help

DonP152

ok. I'm now open to suggestions to replace this pos Navien. Tech support was no help. After 4 years since converting from oil, dealing with 3 Rinnai's (see link for prior thread in first post) and 2 Navien's I don't have the energy left to fight anymore. I have ample space to install additional separate water heater if needed, I need to get forced hot water heat and domestic hot water. It would need to be the same type of exhaust vent as I currently have which is through PVC. It would need to be propane fired. I can have my local tech spec the appropriate model for my home's setup and sq footage, but what I would like know is basic brands that you all consider as trustworthy and reliable.

Ironman

What type of heat emitters do you have? Have you ever done, or had someone do, an accurate heat loss calc? How much domestic load?
If you're as frustrated as it seems, then I would look to installing a good mod/con with an indirect water heater.

There are several good models available. Any model with a fire tube heat exchanger is good. The Dunkirk/Utica laser tube is an excellent design. And of course there's Buderus and Viessmann who have proven track records here and in Europe.

A competent hydronics pro is THE most important part of the equation. Ordinary plumbers and HVAC techs usually don't hydronics well.

DonP152

Update 12-27-2014
Had a certified tech out. Navien emailed me new testing specs and changed the air/gas differential from 1.836 to 1.819 (I don't really know what that means) but... after adjusting levels for both high fire and low fire, CO levels came down to 143 ppm at high fire and 140 ppm at low fire / normal modulation. The tech actually said it's the best he's ever gotten for a Navien. We agreed that I should test again in 6 months to see if there is any change. When I queried him as to why the air/gas ratio would have changed on it's own, he was baffled. He did say that my original installer Paul Feeney (now the Navien tech rep for the northeast) did not replace the lock nut on the adjusting screw so that might have had something to do with it.
I will reiterate for anyone considering Navien.
Noise
And
Vibration
In
Every
Navien
Many thanks to all of you for your help, suggestions and input!