Navien NCB-210E DHW error E001

[jvasco2010]

Hello,

I have a Navien NCB-210E that has been serving inconsistent DHW temps. The temp is set to 130 F, but the temps while calling climb pretty fast to 160-180 until it calms itself and repeats. If you call for hot water on more than 1 tap, the temp will get to 210 and trigger the auto shut off (error E001). This boiler also has space heating for 3 zones, and all of that works fine.

The unit is 4, maybe 5 years old. I've owned the home for about a year, and unsure if it has ever been serviced. I did service it myself about 6 months ago (Cleaned air filter, dirt trap, inlet water filter -was clean as a whistle), and things were fine up until a few weeks ago.

After some research, I figured if I called a tech, the first thing they would do is flush the heat exchanger - so I got a pump and ran vinegar through it for an hour last night. There was some scaling, but nothing crazy for potentially never being serviced. The issue appears to remain, however.

I noticed the PSI at idle is ~11.4, and it will not change when calling for hot water. I've read I should be seeing it raise to at least 20 during operation. I want to say around when this issue started, we noticed a very slight drop in pressure in the shower, but didn't think much of it until 1-2 months later when the inconsistent temps (and eventually E001 code) were realized a few weeks ago and assuming it's all related.

The flow rate shows 1.8GPM when one of the taps is wide open, so the sensor is apparently working.

Any ideas? I'm happy to give more information, and appreciate any help offered!

 

[Fitter30]

Did you run vinegar or a commercial cleaner through it? That's part of yearly maintenance. There is a possibility that after cleaning the heat exchanger will start to leak. The minerals create hot spots in the passages in the heat exchanger causing the tubes can twist creating a hole that minerals have stopped it up.

 

[Sponsor]

 

[jvasco2010]

Hello, yes I ran vinegar for about an hour, and no change in results.

I believe I may have drilled the culprit down to the 3 way valve, as the space heating supply side gets warm while calling for DHW.

 

[Bannerman]

I noticed the PSI at idle is ~11.4, and it will not change when calling for hot water

I expect that ~11.4 psi pressure, will be for the closed loop hydronic heating system, not the DHW supply.

At idle, the DHW pressure should be equal to the cold water supply pressure.

got a pump and ran vinegar through it for an hour last night.

- What is your water source? (Municipal or private well?)
- Is there a functioning water softener supplying softened water to the NCB?
- If no softener, and private well, how hard is the water, and how much iron and manganese in the raw well water?
- If municipal supply, hardness level of the water when tested at your location? (Hach 5B Total Hardness Test Kit recommended)

As you said some scale residue was evident following a 1-hr descaling, leads me to expect no softener is utilized. As you suspect no annual descaling was previously performed, perhaps a 1 hour descaling with ? strength vinegar, is insufficient to remove 5 years of scale accumulation. The amount of scale that was observed, could be only a small portion that became initially loosened, with a larger amount continuing to remain?

the temp will get to 210 and trigger the auto shut off (error E001).

An online search for an E001 error code for a Navien NCB-210E, provided the following result: "Error code E001 on a Navien NCB-210E boiler typically indicates an overheating issue, often related to the heat exchanger or circulation pump. This can be caused by reduced water flow, potentially due to air in the system or a malfunctioning pump."

 

[jvasco2010]

I expect that ~11.4 psi pressure, will be for the closed loop hydronic heating system, not the DHW supply.

At idle, the DHW pressure should be equal to the cold water supply pressure.


- What is your water source? (Municipal or private well?)
- Is there a functioning water softener supplying softened water to the NCB?
- If no softener, and private well, how hard is the water, and how much iron and manganese in the raw well water?
- If municipal supply, hardness level of the water when tested at your location? (Hach 5B Total Hardness Test Kit recommended)

As you said some scale residue was evident following a 1-hr descaling, leads me to expect no softener is utilized. As you suspect no annual descaling was previously performed, perhaps a 1 hour descaling with ? strength vinegar, is insufficient to remove 5 years of scale accumulation. The amount of scale that was observed, could be only a small portion that became initially loosened, with a larger amount continuing to remain?


An online search for an E001 error code for a Navien NCB-210E, provided the following result: "Error code E001 on a Navien NCB-210E boiler typically indicates an overheating issue, often related to the heat exchanger or circulation pump. This can be caused by reduced water flow, potentially due to air in the system or a malfunctioning pump."

Thanks for the reply. The psi belonging to the space heating makes sense, and thinking more about what I suspect the 3 way valve being the issue is from my previous comment (not approved by moderator yet) , is that I did notice the psi go from 11.4 to 11.6 and back down while calling for DHW.

So I'm assuming between being able to feel the space heating supply get warm, and the psi raising slightly, leads me to believe the valve is indeed not closing completely and excess water is making it's way into the heating loop.

I don't think I'm dealing with hard water (municipal) since there was no change at all after flushing, and the other symptoms above wouldn't add up if it were scaling alone.

I'm having a Navien tech confirm Thursday morning (before i dig out that valve for nothing), and will update here.

Appreciate the help!

 

[DIYorBust]

I've been battling this problem for a while with my NHB heating only unit. It does not have an integral pump as your does. In my case, I think the problem may be air in my system, but seems less likely on a DHW unit because you can see the water coming out at the taps and it's not full of air. I'd guess the most like issue is that the integral pump is on the fritz, but it could also be the circuit board failing to call properly for circulation. You might be able to test if the pump is receiving power when you're getting your e001 using a multimeter. If it's not, consider replacing the circuit board. If the power is coming on to the pump, but the pump is not running, consider replacing the pump.

 

[John Gayewski]

Do you have recirculation on your domestic hot water system?

 

[jvasco2010]

Thanks for the replies everyone. The Navien tech checked things out and didn't completely rule out the 3 way valve, but also noticed a decent amount of air in the system (you could hear noticeable whooshing sounds in the heat exchanger which isn't good). I did try to bleed a bit through the circulator pump in the past, but it wasn't nearly enough.

He also noticed the 11.4 psi was fairly low on the space heating side, and apparently the auto-fill won't kick in unless the psi drops under 10-12 (or 4 under whatever it's set to), so he thinks the air that has accumulated over time has prohibited the auto-fill to not kick in since the air was tricking it into thinking more water wasn't needed. And so this air eventually makes its way into the heat exchanger and can get trapped. He upped the psi a bit to try and avoid falling into that window again.

Once he purged the "impressive amount of air", the DHW temps were definitely more consistent (albeit I still see temps rise a little faster than I believe I used to see in the past, but maybe I'm just overly scrutinizing). He said if the issue returns soon then it could be the valve, but as of now the issue has subsided.

On top of purging the air, he suggested replacing the spirovent internals as well as adding an external water fill which would ease the purging process and help keep the psi stable. I don't think I'll do that just yet, however. I just got a whole home heat pump, so the boiler space heating may only be used in times of emergency, so I'm hoping the issue won't return if it was indeed the space heating side contributing to the air.

Thanks again for all the input, it's appreciated!

 

[Reach4]

Where is the air going to come from?

Is this a 3-story house, that will need more pressure?

 

[jvasco2010]

Where is the air going to come from?

Is this a 3-story house, that will need more pressure?

I guess over the years water can evaporate a little along with micro bubbles in the tap used for the auto-fill. Also if the spirovent is firing often (and the water was pretty dirty that comes out), then it can clog a bit and air that would normally escape can get sent back through the loop - is I think how I understood..

This is a 2-story house with a basement.

 

[Fitter30]

Take a few pic of the heater piping and pump and expansion tank. Height difference from the lowest heating water to the highest point.
Dhw
C outlet temp
D inlet temp
E flow.rate
Heating side
R water pressure set point. Default is 6 lbs
Service manual
www.manualslib.com/manual/1059790/Navien-Ncb-150e.html?page=2#manual
Need to get some litmus paper that starts at 1. Before cleaning starts vinegar is 2-3 ph when it gets to above 5 add more vinegar run for 30 minutes recheck ph add more vinegar do this till it doesn't rise over 5 for 30 minutes then you know its clean

 

[Reach4]

I would use an inexpensive pH meter calibrated with the 4.01 calibration solution.

https://www.ebay.com/itm/225361540744

I suspect there could be a leak causing more water to be added. Turning off the valve to the feed water could identify that.

It could also be that there is a problem with the thermal expansion tank, and the water is being released from the pressure relief, and new water is being drawn in repeatedly.

 

[DIYorBust]

If you are wanting to test the pH, consider using a phenol red test kit, these are not too expensive and more precise and easier to read than litmus paper in my experience. But my thinking is that microbubbles introduced with the makeup water is unlikely to accumulate in such a large amount in the boiler as to air lock it or the pump. Even frothy water should make it's way through. However I do believe I've had an issue on my heating system where shutting off the water and draining it down for maintenance caused the makeup water supply to fill with air. When the water is turned back on, air spurts out of all the faucets for a few seconds before water comes. Because the air eliminator is usually on the hot side of the boiler, air in the water supply will have to make it's way through the boiler before it's eliminated, and this could cause an E001. Depending on the manifold, it could be difficult to purge the primary loop, but using the flush ports may help. It may be possible that what appears to be air could also be steam formed from boiling water in the heat exchanger if the pump isn't doing it's job. Could be an issue with scale, but not hearing reduced flow on the DHW side, and even with frequent makeup water, it would take a lot to clog the heating side, but it's possible.

 

[Fitter30]

If you are wanting to test the pH, consider using a phenol red test kit, these are not too expensive and more precise and easier to read than litmus paper in my experience. But my thinking is that microbubbles introduced with the makeup water is unlikely to accumulate in such a large amount in the boiler as to air lock it or the pump. Even frothy water should make it's way through. However I do believe I've had an issue on my heating system where shutting off the water and draining it down for maintenance caused the makeup water supply to fill with air. When the water is turned back on, air spurts out of all the faucets for a few seconds before water comes. Because the air eliminator is usually on the hot side of the boiler, air in the water supply will have to make it's way through the boiler before it's eliminated, and this could cause an E001. Depending on the manifold, it could be difficult to purge the primary loop, but using the flush ports may help. It may be possible that what appears to be air could also be steam formed from boiling water in the heat exchanger if the pump isn't doing it's job. Could be an issue with scale, but not hearing reduced flow on the DHW side, and even with frequent makeup water, it would take a lot to clog the heating side, but it's possible.

If there is air in the water the flow sensor would be jumping. When draining any dhw or heating system the main water valve that.is shut off has a solid water up to the valve. Draining the system introduced air into the piping in either case. Boiler water needs air bleeds open filled slowly to push as much air as possible. Then the main pump is started boiler is off and the auto air vent or vents do there thing. Then start the zone pumps one at a time let the air device work.
DHW air is in all the piping water has to push all the air out again don't want to open water supply wide open.If the system has air chambers for hammering widw open can displace the air in them and won't do their job.

 

[jvasco2010]

Hi All,

Just to update for anyone else lurking - This issue has been resolved. I replaced the 3-way valve and the circulation pump.

I think running the space heating in the past made things work temporarily from the external Taco pump helping the weakened internal circulator pump.

I'm back in business. Thanks everyone for your input!