Navien NPE-240A NG Leaking

[ilans1]

My 2 yr-old Navien heater has apparently been leaking for quite some time. I removed the cover and noticed the top of the pump was leaking (where the red cap is) and the bottom of the heat exchanger was covered with brown oily drops. Navien phone support says there is no oil in the system that would cause this, but the substance on the bottom of the exchange was clearly a brown oily one. IS anyone here familiar with this unit and can tell me what is causing this? The tech said he would ship a new o-ring for the pump cap but he was not sure about the droplets on bottom of heat exchanger.

Thanks

 

[WorthFlorida]

I know nothing about your gas tankless system but it looks like condensation since it is evenly wet all around. A leak would be one location dripping down. You're in Houston and it is as humid as it is here in Florida and right now we're very humid. If this tank is in the garage or an outside location, the warm humid air is condensing because at the bottom of the tank is probably where the cold water enters and it is heated further down the line away from the bottom. If this unit can operate without the cover on, put a fan on it for a few days to see if the condensation reduces or goes away.

In the short time wipe it down with a towel and use a hair dryer to dry it out. Either run the hot water or take a look every so often. If it comes back all wet slowly then it is condensation. If you have the temperature of the cold water, the air temp and the known humidity, you can find the dew point of the air. http://www.dpcalc.org/ If the dew point is above the cold water temp, it is definitely condensation. As an example, the air is 85 degrees (the garage door closed with a car with a hot engine) and the humidity is 80% the dew point is 78 degrees. If your cold water temp is 75, like most of Florida, that is when condensation will occur.

 

[Sponsor]

 

[Vinci11]

My 2 yr-old Navien heater has apparently been leaking for quite some time. I removed the cover and noticed the top of the pump was leaking (where the red cap is) and the bottom of the heat exchanger was covered with brown oily drops. Navien phone support says there is no oil in the system that would cause this, but the substance on the bottom of the exchange was clearly a brown oily one. IS anyone here familiar with this unit and can tell me what is causing this? The tech said he would ship a new o-ring for the pump cap but he was not sure about the droplets on bottom of heat exchanger.
View attachment 39905

Thanks

I have the exact same issue. The substance feels and looks oily, it does not dry rapidly like condensate should when you run a finger through it. Your finger stays oily feeling until you wipe it or wash it off.

My heaters (one master/one slave in a circulating system) worked fine until we suddenly stopped getting hot water from the faucets quickly a few weeks back. Hot water would eventually arrive, but it was slow, like the recirc pump had failed. The service techs came out today and pulled the covers from both units.

The master unit had the oily condensate, looks exactly like your picture, and the other did not. The slave was completely dry inside. Navien tech support said they had never seen the issue, but did indicate that the DIP switches on the two units were set wrong. After the DIP switch settings were changed, I now have instant hot water again. Strange that the system would work fine with the wrong settings for nearly 4 years, then stop.

I will say that the uniform presence of the oily stuff all over the bottom of the heat exchanger AND up high in the unit where there's more black plastic around the exhaust does make it look like condensation. But, the substance is definitely oily, not just water condensate.

The service techs wiped down the unit with the oil inside and just said that we should monitor the situation. If anyone else experiences this situation, especially if they find the problem, I hope you'll sign up and post here!

 

[Foamer 44]

Add me to this train. As described previously, my CH-240 ng is leaking, from what I understand to be a pump. The circumstances appear to be due to an increased use of the radiant side of the system, as the weather has started to cool off. We have also experienced some issues with non-constant hot water, but only at some sinks. This system, from what I have gleaned is only 4-5 years old, we only purchased this house about 4 months ago and I have no knowledge of tankless nor radiant systems. Of course naturally there is no manual, but I did find a link yesterday which I have yet to investigate.

As others, any thoughts on this issue are highly sought.

 

[WorthFlorida]

...As others, any thoughts on this issue are highly sought.

Read what Vinci11 stated about dip switches: "The master unit had the oily condensate, looks exactly like your picture, and the other did not. The slave was completely dry inside. Navien tech support said they had never seen the issue, but did indicate that the DIP switches on the two units were set wrong. After the DIP switch settings were changed, I now have instant hot water again. Strange that the system would work fine with the wrong settings for nearly 4 years, then stop."

 

[HoustonWH]

Any more news about this?

I was looking at my 3-year old Navien NPE 240A, which has quit heating up enough during higher-flow (water is warm, but not hot enough when set on 120-deg F), and noticed the exact same oily condensation. Definitely NOT water; wiped off on a paper towel, and it is yellow and oily. Located on the black plastic areas on top and bottom of unit; but not on the metal parts. I'm still trying to figure out why it doesn't perform same as new, and flushed it with vinegar a few days ago. Perhaps a flow sensor is bad.

 

[WorthFlorida]

Do you think the water droplets are all oil? I’m wondering if the plastic had some kind of coating and the droplets are water. Wiping it your rubbing the film off with the water, really strange. I’ve never seen oil droplets like that.

 

[HoustonWH]

Do you think the water droplets are all oil? I’m wondering if the plastic had some kind of coating and the droplets are water. Wiping it your rubbing the film off with the water, really strange. I’ve never seen oil droplets like that.

I am thinking it might be products of combustion - some of the flue gases may be hanging around inside the cabinet (the unit is indoors) and condense when the hot heat exchanger cools down; it's been very gradual. I didn't notice the droplets last time I de-calcified the system.

 

[WorthFlorida]

Is the cabinet airtight or does it have grates for air flow? You synopsis may be correct.

 

[Ccimino]

Has anyone determined how the oil droplets form? Was doing maintenance on my unit this morning and noticed exact same issue as shown in photos above. Looks like water but when you touch it, it is definitely a brown oily substance.

 

[JeanLuc]

I have the the same issue: 3 yr young unit. This is the first time the drops appeared. Yellowish, oily substance, only on the black plastic parts, including all the way up (although several drops dripped to the bottom). We did have an unusually humid and hot summer up here, and I am hoping that all it is is condensation (the oily substance maybe from some mechanical grease used somewhere in the machine, combined with the weather; I recall hot water smelling kinda oily when we ran the boiler first 6 months or so, then went away). Fingers crossed...

 

[Bob F]

We have a 2 y/o 240A and it has the same oily condensation on the black plastic parts. The installing plumber has never seen it and the supply shop he bought it from has no idea either. Has anyone heard of the cause/fix yet?

 

[Verucktjim]

I have the same oily issue. I Also noticed a wire harness that was resting above the boiler. The wire harness was dried out and falling apart. The unit was installed in 2016. I thought maybe the oily residue was from the Oils in the wire harness. I contacted Navien And they said
Thank you for contacting Navien. The oily substance can be a result of exhaust circulating back into the intake due to incorrect venting installation. Please, do not operate the unit until this issue has been checked out by a licensed technician. When onsite have them call 1-800-519-8794 ext 2.
The company that installed the unit is suppose to get back to me. I will let you all know the final outcome.

 

[WorthFlorida]

In the meantime get a carbon monoxide detector for your furnace room. Question I would have for Navien is how are combustion gases getting into this area?

From Navien web site. It would seem to be pretty difficult to have vent issues unless an old chimney or metal flue was used.

https://www.navieninc.com/series/npe-s/faq#collapse1202
The NPE is approved to be vented with 2”vent material (maximum length of 60’, maximum of 6 elbows, and reduce 8 linear feet per 90° elbow). 3” vent material can also be used (maximum length of 150’, maximum of 8 elbows, and reduce 5 linear feet per 90° elbow).

Approved vent materials are PVC Schedule 40, CPVC Schedule 80, ApprovedPolypropylene.

 

[Verucktjim]

Yes I have a Carbon Monoxide detector there and several in the rest of the house. The company who installed it are coming Tuesday.
But to be honest I don't think the problem is the venting. But when they get here I really want them to call Navien and see what they say?
I really hope I didn't make a bad choice going with this Combo boiler? It looks good! But will it stand up to use and will I have major headaches when it breaks down?

 

[Dana]

Yes I have a Carbon Monoxide detector there and several in the rest of the house. The company who installed it are coming Tuesday.
But to be honest I don't think the problem is the venting. But when they get here I really want them to call Navien and see what they say?
I really hope I didn't make a bad choice going with this Combo boiler? It looks good! But will it stand up to use and will I have major headaches when it breaks down?

Low mass combi boilers are usually WAY sub-optimal for the average house. They're a good fit for houses with much higher than average space heating loads combined with modest to average water heating needs. (Say 2 people living in an uninsulated 5000' house.)

If you think you may end up replacing it there are two bits of napkin-math analysis worth running on your system and heating history:

First, get a good handle on the design heat load by using wintertime fuel use against heating degree-day data. You'll find that at high fire even the smallest wall hung combi boilers are usually 2x-5x more burner than is needed for heating the place.

Then, analyze the amount of heat emitter you have on each zone for how much heat it can deliver at and average water temp of 120F, which is what it takes to actually get the mid-90s efficiency out of these things. If the radiation can't emit the full minimum-modulated output of the boiler it will be forced into cycling on/off rather than modulating the firing rate with heat load, which puts a lot of wear & tear on the boiler, and cuts into as-used efficiency.

The minimum fire output of the NCB 210E and 240E is about 17,000 BTU/hr, which would take 75-85 feet of typical fin tube baseboard per zone to run at 95% efficiency most of the time. If the heat load of the whole house is only 25,000 BTU/hr @ +15F (NYC & L.I. type 99% outside design temps) it's not really going to modulate much even if there is enough radiation to keep it from short-cycling.

As long as it's not short cycling at condensing temperatures it's not an efficiency disaster or particularly "...bad choice...", but for 19 out of 20 houses in NY it's not exactly a good choice either.

If it turns out yours is short cycling there are several programming parameter tweaks to minimize that and get more useful lifespan out of the thing. To advise intelligently we'd have to run at least the napkin math analyses on the system. If the radiation is high volume cast iron radiators there is a lot of forgiveness built-in, and even if under-radiated short cycling can usually be suppressed. For fin-tube baseboard & cabinet convectors it's more iffy.

 

[Verucktjim]

So the Navien tech told the guy from the install company that the street Elbow that he used on the exhaust was no good. Needs to be a pipe. After I thought about this it makes sense the street Elbow was pinching the bottom rubber seal, damaging it in the process.
New rubber gasket coming soon. And hopefully they fix the connection properly.

 

[Dana]

I thought I'd seen everything, but that's a new one on me! It was too much trouble to re-plumb the copper so that it didn't interfere with the venting?

 

[Verucktjim]

So the rubber seal was replaced and a new strait pipe installed. Now I will keep an eye out for oily residue.
As far as I know Many of these Navien units have this problem. Hopefully this will fix it.

 

[Navien Inc]

View attachment 55268 View attachment 55269 So the rubber seal was replaced and a new strait pipe installed. Now I will keep an eye out for oily residue.
As far as I know Many of these Navien units have this problem. Hopefully this will fix it.

Thank you for updating this forum with the information you obtained about correcting the venting. It’s important that anyone else with this installation mistake gets it fixed. If anyone is unsure about whether or not their venting has a secure seal or any other issues with the unit, installation, or performance, our technical support department is available extended hours at 800-519-8794 option 2. Thank you. –Navien, Inc.