Navien NPE-240A Recirculation Question

[Ed Boston]

Hi all, we had a Navien NPE-240A installed in 2014, and have been happy with it. We did have a weird issue with water temperature being colder than expected occasionally, but it always went away. This year we switched to a new servicer who told us it had been installed wrong and was set to external recirculation even though we don't have an external recirculation line. They switched it to internal recirculation and the temperature problem went away.

I don't know what to expect from internal recirculation but it seems like it runs very frequently and the noise from the pump is annoying (not really loud, but audible on the first floor and annoying). Is this how it normally functions? Would turning on Intelligent mode help reduce this? I'm also thinking about just turning the recirculation off completely because of this - does anyone do that?

Thanks very much in advance for your help.

 

[Breplum]

With internal recirculation dip switch setting the onboard mini tank/buffer tank is being monitored and kept up to temp, so that is why it is coming on. The set of 10 dip switches should all be off except 1 should be ON.
If you don't take advantage of internal recirc, then you will have to wait longer for the water to be hot.
At worst, you can turn switch 1 off and see how it is. alternatively
You can definitely try also turning dip sw 2 ON for Intelligent Preheating. Give it two weeks to fully learn your use patterns.

 

[Sponsor]

 

[Ed Boston]

With internal recirculation dip switch setting the onboard mini tank/buffer tank is being monitored and kept up to temp, so that is why it is coming on. The set of 10 dip switches should all be off except 1 should be ON.
If you don't take advantage of internal recirc, then you will have to wait longer for the water to be hot.
At worst, you can turn switch 1 off and see how it is. alternatively
You can definitely try also turning dip sw 2 ON for Intelligent Preheating. Give it two weeks to fully learn your use patterns.

Thank you - that is very helpful.

 

[Quark]

I'm also thinking about just turning the recirculation off completely because of this - does anyone do that?

We have a 240A but with an external recirculation line. We, too, have a pump noise issue at night because the 240A is in a small closet near our bedroom. There are 42 minute "quiet time" intervals between the 5 minute pump runtimes; therefore, during an 8 hour period (10PM to 6AM), the pump cycles 9 or 10 times. If I we can simply turn off the 240A at 10PM and turn it back on at 6AM, that would be our preference. Otherwise, I am looking at soundproofing the closet. I did ask a Navien tech about turning off the 240A for this purpose, but his answer was a bit ambiguous and I got the impression he was not fully up to speed on the 240A.

 

[TJanak]

We have a 240A but with an external recirculation line. We, too, have a pump noise issue at night because the 240A is in a small closet near our bedroom. There are 42 minute "quiet time" intervals between the 5 minute pump runtimes; therefore, during an 8 hour period (10PM to 6AM), the pump cycles 9 or 10 times. If I we can simply turn off the 240A at 10PM and turn it back on at 6AM, that would be our preference. Otherwise, I am looking at soundproofing the closet. I did ask a Navien tech about turning off the 240A for this purpose, but his answer was a bit ambiguous and I got the impression he was not fully up to speed on the 240A.

The NaviLink wifi controller will allow you to do this. It cannot be done in the 240A alone, the NaviLink controller is needed.

 

[Ed Boston]

We have a 240A but with an external recirculation line. We, too, have a pump noise issue at night because the 240A is in a small closet near our bedroom. There are 42 minute "quiet time" intervals between the 5 minute pump runtimes; therefore, during an 8 hour period (10PM to 6AM), the pump cycles 9 or 10 times. If I we can simply turn off the 240A at 10PM and turn it back on at 6AM, that would be our preference. Otherwise, I am looking at soundproofing the closet. I did ask a Navien tech about turning off the 240A for this purpose, but his answer was a bit ambiguous and I got the impression he was not fully up to speed on the 240A.

I did wind up turning it off for now because of noise. Interestingly my perception is that the run times were much longer than five minutes. I haven’t timed it but I was wondering if there was something wrong because they seemed so long and frequent.

 

[Quark]

I believe the runtime is controlled by one or more these Parameters: P.12 (Preheat Pump Output Time), P.14 (Preheat Interval Time) and P.15 (Preheat Offset Temp). I have P.12 set to 15 minutes, P.14 set to 60 minutes and P.15 set to 9*F. Below (bold lettering) is my understanding of how these parameters control the pump:

240A checks the water temperature in the external recirculation line every M minutes, where M is the value in P.14. The Circulation Pump will activate if the water temperature in the external recirculation line is equal to or less than D degrees below the desired water temperature (Front Panel display temperature), where D is the value in P.15. The Circulation Pump will run for up to M minutes, where M is the value in P.12. For example, if the desired water temperature is 120 degrees and the water temperature in the external recirculation line cools to 111 degrees or less, then the Circulation Pump will activate following a 60 minute check of water temperature in the external recirculation line and will run for up to 15 minutes.

However, my understanding does not quite match up to my observation of actual runtimes. I am going to call Navien tech support and inquire about two questions: 1) Can I turn off the 240A at night and 2) Is my documented observation of night time runtimes consistent with the Parameters? fyi, I recorded runtimes using the Voice Memo app on my iPhone.

 

[Ed Boston]

I believe the runtime is controlled by one or more these Parameters: P.12 (Preheat Pump Output Time), P.14 (Preheat Interval Time) and P.15 (Preheat Offset Temp). I have P.12 set to 15 minutes, P.14 set to 60 minutes and P.15 set to 9*F. Below (bold lettering) is my understanding of how these parameters control the pump:

240A checks the water temperature in the external recirculation line every M minutes, where M is the value in P.14. The Circulation Pump will activate if the water temperature in the external recirculation line is equal to or less than D degrees below the desired water temperature (Front Panel display temperature), where D is the value in P.15. The Circulation Pump will run for up to M minutes, where M is the value in P.12. For example, if the desired water temperature is 120 degrees and the water temperature in the external recirculation line cools to 111 degrees or less, then the Circulation Pump will activate following a 60 minute check of water temperature in the external recirculation line and will run for up to 15 minutes.

However, my understanding does not quite match up to my observation of actual runtimes. I am going to call Navien tech support and inquire about two questions: 1) Can I turn off the 240A at night and 2) Is my documented observation of night time runtimes consistent with the Parameters? fyi, I recorded runtimes using the Voice Memo app on my iPhone.

Very interesting, thanks. Please do check back in when you receive a reply from them. I'd like to run the internal recirculation but not if it means such frequent noise and energy usage.

 

[Bannerman]

If I we can simply turn off the 240A at 10PM and turn it back on at 6AM, that would be our preference.

The Intelligent pre-heating feature will learn your hot water usage patterns over 2-weeks. Since the system will recognize no hot water is utilized between 10pm and 6am, it will then suspend recirculation during that period except for a few minutes before hot water is normally required so as to pre-heat the buffer tank and loop before hot water will be actually drawn.

 

[Quark]

I spoke with Navien support this morning.

Regarding turning the 240A OFF at night and ON in the morning, there are no problems as long as the 240A is not exposed to freezing temperatures. The tech suggested using the Remote Controller (Part #30009757A) instead of manually turning the 240A OFF and ON. Do NOT rely on this advice if you have the newer 240A2 model.

Regarding the actual, observed runtimes (9 times for 5 minutes every 42 minutes) of our 240A pump between 9:45 PM and 5:30 AM, the tech believes the unit is working in accordance with our P.12, P.14 and P.15 settings. I don't get this but whatever.

Regarding Intelligent Preheating and suspending pump cycling at night, this would serve the purpose but the caveat here is that enabling Intelligent Preheating precludes the use of a HotButton. This makes sense to me.

Regarding the use of a Remote Controller (Part #30009757A) and a HotButton at the same time, the tech told that using the Remote Controller might eliminate the need for a HotButton but that I could use both because the operation of one does not impact the operation of the other. I asked about this because in the thread titled Navien NPE240A- NaviLink, NaviLink App, Recirculation settings And Parameters, there is this comment: "The hot button requires installation of a circuit board into the unit. When the hot button is activated, scheduling is disabled. You can not have both. Ideally, I would like to have a schedule in the morning and then be able to use a hot button later in the day if needed off schedule. There is, however, a work around … If you disable the scheduler in the app, a recirculation cycle will begin. But, you must remember to turn it back on again or your device will continue to recirculate."

In our case, we have two goals: 1) no pump noise at night and 2) timely delivery of hot water at the furthest fixture during the day. It would appear we have a couple of options or combination of options to achieve both goals. I have not yet decided which options will work for us in our particular situation.

 

[Bergy]

Sorry if this is slightly off-topic but I have a question relative to a Navion in NPE240A2 using navi circ. My question is whether the buffer tank is still utilized when you were using the Navi circ?

 

[Vrocket]

I am having a problem with it taking 3 minutes for hot water to get to bathroom. Its the NPE -240A. I have the dip switches all off except #1 on. It there a way to know rather the circulation pump is running? After reading here about the check valve might be stuck? how to check it? Thank you

 

[Bannerman]

I have the dip switches all off except #1 on.

DIP Switch #1 being ON along with the 2-way valve set to Internal, signifies hot water circulation will be internal within the water heater. Those are the appropriate settings to cause the water within the WH's internal buffer tank to be maintained at the desired temperature, but will not cause hot water circulation through the home's plumbing to reduce the time for hot water to arrive at distant faucets.

For hot water to circulate through your home's plumbing, your home would need to be equipped with either a dedicated return line, or, a crossover valve such as Navien's NaviCirc would be required so as to use your home's cold water plumbing as the recirculation return path back to the WH.

Is your home equipped with either a dedicated hot water return line back to the WH, or a NaviCirc crossover valve?

 

[Vrocket]

Yes it has a dedicated return line.

 

[Bannerman]

Assuming your dedicated return line is connected to the WH's recirculation return connection, then the WH's internal 2-way valve will need to be placed in the 'External' position and the DIP switch settings will need to be as per the Installation Manual, page 45:
Circulation using the NPE-240A Internal pump.
EXTERNAL CIRCULATION (Continuous circulation whenever the return water temp is too cool) 1:OFF, 2:ON, 3:OFF

INTELEGENT PREHEATING (learns your hot water usage patterns to automatically program a circulation schedule) 1:ON, 2:ON, 3:OFF