Recirculation Control

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Recirculation with water heaters is a feature that has been available for a long time. Recirculation essentially means circulating hot water throughout the building to provide hot water faster at the fixtures, at the users’ point.

With tankless water heaters, recirculation is a little bit different than we've done in the past with standard tanks. On a tankless water heater, we want to make sure that we control the recirculation properly, that we don't cycle the unit too often, then yet we still provide the hot water quickly enough for the end-user to save money on their water bill. By having hot water at the fixture, you now wait less time to get that hot water coming out of that faucet.

There are a couple of misunderstandings about recirculation and tankless water heaters. The first being the term instantaneous. A tankless water heater is not an instantaneous water heater, there still is some time that it takes to get the hot water from where it's at in the line out of that faucet. It may only be a few seconds, but it's not instantaneous, it's an on-demand water heater.

The second is that when I add recirculation to a tankless water heater if it's set up properly, that unit is not running all the time like we used to do with tanks. A tankless water heater will cycle and heat that water only when it's necessary.

The Navien tankless water heaters are available in multiple types including our NPE series which is a condensing unit. The NPE-A is a unit that has a built-in circulator and buffer tank, but it's also offered as a standard unit without those components in there. Both of those units are available as recirculation units if you set them up that way.

Along with that, our non-condensing NPN can also be used in a recirculation system, it just requires the addition of a few extra components.

The NPE series, our condensing unit, has what we call our A unit that A unit has the circulator and buffer tank built into it. There are two different modes in the recirculation features of the NPE series, what we call either internal recirculation or external recirculation.

Internal recirculation will circulate water just inside the unit itself to preheat the unit. That provides hot water almost immediately coming out of the unit itself cutting down the delivery time to the fixtures.

We can also do external recirculation with that unit, which is where we add an external recirculation loop, getting that hot water further down those lines and closer to our fixtures. Again, both modes cut down the amount of time that it takes to get hot water out of our faucets.

The controls on our NPE units and also on our NPN units, allow for multiple types of setup for recirculation control. When we operate an NPE unit, the condensing unit, we can set that up to do what's called intelligent recirc or intelligent preheating, that's a self-learning process. It learns how you use your hot water, and it will circulate at the appropriate time.

We can also set them up using a timer. The NPE series has a built-in one, three, or seven-day time schedule that you can set the specific times to recirculate.

There are options for a HotButton, our product that creates an on-demand type of circulation, along with the option to add an aquastat to recirculate that based on temperature.

So having multiple options we can control that system in whatever way works best for the end-user.

Recirculation benefits the end-user by delivering hot water faster to the fixtures, you don't wait so long to get hot water out of that faucet. But it's also a water-saving device because of that, faster delivery time, we’re not standing there waiting for the hot water to come out of the. faucet.

[cadamham]

Dilemma: waste water or waste natural gas?

[kchiem]

How do I configure the HotButton recirculation to recirculate as long as the other modes when they kick on? The other modes recirculate until the return temp is 9F less than the hot outlet set temp, but the HotButton recirculates only until the return reaches 100F. Worst, it doesn't do this by default either, as the default settings have it running only ~10s; the farthest fixture setting has to be changed from the default of 30 ft to some high unrealistic value (200+ ft) in order for the HotButton recirculation to run long enough for the return temp to rise that high. Whatever formula it's using here to calculate runtime, it's broken, as it doesn't reflect reality.

Edit: Found the solution to the HotButton issue. On my A2 model, turn on dipswitch 2 on the HotButton PCB to disable Energy Savings Mode, and it'll recirc like the other recirc modes. I called Navien Support, and they wouldn't tell me how. Had to google and do a bit of reading to find it. Navien, maybe you guys can also explain why you won't tell me how to configure my equipment to work the way other modes already work. Pretty infuriating how useless support is.

[arjun]

Installed a new 240A2 with navicirc valve at distant sink. What is the settings on the machine internal vs external circulation? Right now there is no pipe entering the recirculating port on the water heater. Please help. Thanks

[JustinDD]

just wondering if running the recirculation all the time is a concern for the pump or system? Only reason I ask is that was a option shown on the menu of your video but the speaker didn't speak to it

[onlyme]

I just installed a Jnod electric combi that has a built in heater for instant hot water.

[stephenbonner]

My NPE-A2 ran perfectly fine using the recirculating system until the end of December. Unit was installed in the late fall of 2022. Now, in either recirculation mode, it no long works, pumping only at a minimum rate, taking 5 minutes or more to get water temp to the set 125 degree temperature. The Navien recirculating valve is installed by our dealership that sold us the tankless. They cannot figure out what the problem is. They claim the pump is working properly, and it does until they leave my home. I'm getting really frustrated and need help. No one has offered to replace the pump or the control board to see if that could be a problem. It is still under warranty. Please help me.

[nicholasali]

My unit is running cold water from time to time. It's brand new. WASN'T an issue a week ago. Should I set it to recirculation mode?

[tkstrike]

Trying to find a solution for the NPE-240a with external recirculation line. The unit was installed over 2 years ago, and dip switch setting is Sw1 & 2 are both on for Intelligent mode. Over the past 6 months, when the recirculation pump turns on, I get pipe tapping noise (like air in line), and are trying to figure out how to fix it. The unit was installed with all PEX lines and insulated. Additionally I wanted to ask if it's okay to lower the pump run time to 10 minutes vs. the default 20 minutes. Thanks in advance for your support.

[shreyasdube]

So, for a NPE-A, for an external recirculation retrofit, I just need that recirculation valve?

[DLiver]

Remote Screen on this video is almost as difficult to read as the remote I have. No way to adjust the backlight.

[jaisvikt]

My timer only offers a scheduled recirc and as we are not robots on a fixed schedule, an "instant" on capability would've been nice. Are there options?

[darrentoth]

I want to do a recirc return line (210A2) is a expansion tank required? Also, at the end of the loop, do I need a normal three way fitting ( from tank, to sink and return to tank) or a swing valve? Thanks!!

[NJR]

Do you folks have a video on how to set the recirculation to intelligent? I just got this hot water heater and haven't had a chance to play with the menu yet. Also, how do I select internal or external?

[marksplace]

If I use it in external circulation mode. Would it hurt the unit if I control the pump seperate from the unit. Would Turing the pump off cause it to over heat seeings that water movement would stop?

[joker-ifgu]

how is the hot water being returned in that loop? is there a dedicated 3rd pipe dedicated that needs to be tied in into faucets? or does it use the cold water line as return .

[dewalt]

I did the hot water outlet in 1" pex and the return reciruclation pipe in 1" is that going to be a problem ? I have the NPE 240A2

[Canvasone]

Can you use multiple crossovers in a recirculation system?

[Encrypt_ed]

What should you do when you have an external unit & when you plug in the recirculating pump it’s stays running and never shuts down. I added the smart plug as well and it’s shuts off but it’ll automatically turns on & off with no by itself with no water calling in the house. When it runs it stays on for awhile before it shuts off

[wallacegrommet]

Same old large corporation video instructions suck.
Manuel useless information in regards to recirc
Get with it people.
Likley, lots of returns.