Navien NR-240(A) - bypassing recirculation

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Mostly clueless

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Hi,

Newbie here and found this forum very useful as I look for a solutions until the plumber gets here *in a week*

Issue:
Hot water stopped working with my older (2010) Navien NR-240A (NG), with an external circulator/small tank. Turned the unit off and then on again after 60 seconds. It starts up, seems to work for a few seconds, and then briefly makes a higher pitched whine - like something was straining a bit. Then it shut down with error 38 on the control.

- Manual says Abnormal circulation pump Check 1) Circulation pump 2) Flow sensor 3) Cold water main line
- Not savvy enough to do most of this, but while it was open, did a descaling and cleaning of filter, condensate etc.

Troubleshooting to get hot water and get rid of error 38:
- Called Navien, but they would only speak with a plumber. (Our licensed guys will take a week to get here.)
- Called Navien-trained plumbers, they will be here in a week.

Workaround wanted:
- Want hot water.

My thinking:
Thought I could turn the device to internal recirculation mode and that would get us hot water until plumber gets here.

Research:
Page 88: "A" series internal recirculation mode:
a) Dip switch set 2, put 4th switch on and 5th off (currently the 4th is off and 5th is on)
b) Manually set the 3-way valve to 'Internal circulation' (it is currently set to external)

So I shut off the cold and hot water via the valves. Tried to move the valve to internal, but it seems rather hard to do. Didn't want to force anything, so thought I'd bring my newbie self here and ask

a) If I am approaching this the right way
b) If the 2-way valve should be this hard to turn, or do I need to loosen something first?

Many thanks in advance.
 

Bannerman

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Since the issue could be the circulation pump or sensor, suggest resetting the 2-way valve to Internal, and setting the switches so there will temporarily be no recirculation active.

With no circulation, the buffer tank temperature will not be maintained so it will likely take longer for hot water to arrive to fixtures, but waiting for hot water will be better than no hot water, at least until the cause of the issue is resolved to allow recirculation to be resumed.
 

breplum

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So you say "with an external circulator" but you likely mean 'internal circulator with external circulation' if it is an "A" model.
I have to say I HATE these old models and I am Navien's biggest trained tech fan in my area.
The old concept of 'smart' tech on those old models stinks.
I really push customers to upgrade to the latest, which is soooo much better in every way as far as control troubleshooting and better parts functions, and ease of swapping out the pump.
I have changed my last pump on the NRs. They are a pain in the a-- because of the stainless steel clip that you have to reach in with great difficulty to secure when we place/replace a pump.
It would maybe worth swaping out the flow sensor. Part number 30010537A
The trouble is, you don't know if the error is from the pump being stalled or the sensor being bad.
If you are going to spend money for a pro, they still have to waste a lot of your money for this klugy process.
Better long term reco is just swap out with new. The prices have not gone up like so many other brands and things with metal parts.

Every time I've pulled a pump and bench tested, they run fine once you smack'em upside.
 

Mostly clueless

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Since the issue could be the circulation pump or sensor, suggest resetting the 2-way valve to Internal, and setting the switches so there will temporarily be no recirculation active.

With no circulation, the buffer tank temperature will not be maintained so it will likely take longer for hot water to arrive to fixtures, but waiting for hot water will be better than no hot water, at least until the cause of the issue is resolved to allow recirculation to be resumed.
@Bannerman - thank you! Yes, so this confirms my approach, which is exactly as you suggested. (resetting the 2-way valve to Internal, changing dip switches.)

However, here is the issue - I can easily change the dip switch settings. But I can't seem to budge the valve, to move it from the 'out' to the 'in' position. I've tried turning the valve to the 'in' position, but can't do it. I've tried with a flat head screwdriver to move the knob from the current ext position, to no avail.

I don't want to damage anything, so haven't tried a lot of force yet. Is there something else obvious I am missing? (For example I didn't try to loosen anything else before.)
 

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Mostly clueless

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So you say "with an external circulator" but you likely mean 'internal circulator with external circulation' if it is an "A" model.
I have to say I HATE these old models and I am Navien's biggest trained tech fan in my area.
The old concept of 'smart' tech on those old models stinks.
I really push customers to upgrade to the latest, which is soooo much better in every way as far as control troubleshooting and better parts functions, and ease of swapping out the pump.
I have changed my last pump on the NRs. They are a pain in the a-- because of the stainless steel clip that you have to reach in with great difficulty to secure when we place/replace a pump.
It would maybe worth swaping out the flow sensor. Part number 30010537A
The trouble is, you don't know if the error is from the pump being stalled or the sensor being bad.
If you are going to spend money for a pro, they still have to waste a lot of your money for this klugy process.
Better long term reco is just swap out with new. The prices have not gone up like so many other brands and things with metal parts.

Every time I've pulled a pump and bench tested, they run fine once you smack'em upside.
Thank you @breplum - appreciate your experience and thoughts.

Not sure how much longer we will be in this house - year or two max?
 

Mostly clueless

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So you say "with an external circulator" but you likely mean 'internal circulator with external circulation' if it is an "A" model.
I have to say I HATE these old models and I am Navien's biggest trained tech fan in my area.
The old concept of 'smart' tech on those old models stinks.
I really push customers to upgrade to the latest, which is soooo much better in every way as far as control troubleshooting and better parts functions, and ease of swapping out the pump.
I have changed my last pump on the NRs. They are a pain in the a-- because of the stainless steel clip that you have to reach in with great difficulty to secure when we place/replace a pump.
It would maybe worth swaping out the flow sensor. Part number 30010537A
The trouble is, you don't know if the error is from the pump being stalled or the sensor being bad.
If you are going to spend money for a pro, they still have to waste a lot of your money for this klugy process.
Better long term reco is just swap out with new. The prices have not gone up like so many other brands and things with metal parts.

Every time I've pulled a pump and bench tested, they run fine once you smack'em upside.
@breplum - the tech came out - was very good and knowledgeable. Back to hot water, but no recirculation. They spent time with Navien and at the end they also suggested what you did - swap out for a new unit.

They are recommending the 240A2. Question: given the setup, which one would you recommend? The NPE A2 or the NPE SE2? (Picture attached of current setup.

PXL_20220516_200652978~2.jpg
 
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Buildergarcia

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Error code 38, shut of all supply water to the tank, drain down, find the flow sensor and remove it, the sensor is front and center in my unit. Check that the small turbine rotor runs free in the sensor as a small piece of scale will stop it from turning.... reinstall .. it worked for me!
 
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