Navient 240A recirc

[SoCalDave]

Hi all,

I am finding conflicting info, hoping someone can clarify for me.

I have a Navien 240a with internal recirc pump. I just had a dedicated loop installed. It is a relatively short run - less than 100'. They installed 1/2" copper. Looks like Navien approves of 1/2" for under 100" - will 1/2" cause any issues?

Back to my main question - I see that I need to flip DIP 1 on to enable internal recirc. Should I also flip DIP 2 on to enable intelligent recirc? Does anyone have experience with intelligent recirc? Does it work well?

Thank you!!
-David

 

[Twowaxhack]

@breplum

He knows all about these POS.

He’ll be able to help you

 

[breplum]

Intelligent recirc works ok if your schedule works out to fair regularity, because it learns the use pattern over many days, and keeps checking that pattern and adjusts.
What it doesn't do well is accommodate irregular schedules.
So, just try it and definitely give it some time.
If it is a modern unit, you can also opt to add the low voltage pushbutton kit to call for recirc. truly on-demand.

 

[SoCalDave]

Thank you, @breplum. Would using internal recirc without the intelligent recirc be any better if schedules are irregular?

And if I use pushbutton, do I have to run wire to the bathrooms?

Would each bathroom/kitchen have its own button?

Is there any wireless option with the button?

And lastly, is the pushbutton preferable over the intelligent recirc?

 

[breplum]

Full time recirc benefits from the built-in aquastat and will shut off when the return temp reaches set point.
Older "A" series had an optional stupidly designed timer that allow for specific on/off segments.

Yes, low voltage thermostat type wire is all that is necessary, and yes, each bathroom gets a pushbutton.
Navien does not have a wireless option. There are wireless pushbutton and even wired and wireless motion detectors out there aftermarket.

 

[SoCalDave]

Thank you for all the info. Given the options, would you say full-time recirc is the most effective?

My wife doesn't want buttons in the bathrooms. I am still going to run wires while the walls are open, just to future proof in case we change our mind in the future.

But in the mean time, if we go without buttons, would you suggest full-time recirc?

Thank you!!
-David

 

[breplum]

Recirc "on" is fine but you can also try the intelligent as a multi week trial some time too.
1/2" is ok if it says 100'. Make sure that long sweep elbow fittings are used and min. 3/4" wall insulation is used.

 

[SoCalDave]

Sounds good. I will try intelligent first and see how it does. If that doesn't work well, I will try always on.

Regarding 1/2" copper, it is much shorter than 100 feet... probably closer to 50, possibly less. I will measure. But, they did not use long sweeping elbows...will that be a problem? There aren't many elbows in the run. Picture attached - recirc marked with red arrow.

I will make sure they insulate at least 3/4".

Thank you!
-David

 

[Twowaxhack]

I’m working on a circ system right now where they used 1/2” copper for the return with short 90’s. It’s worked for 20 yrs and it runs 24/7. They average 7 yrs out of a pump before it dies. No fitting leaks.

 

[SoCalDave]

Thank you, @Twowaxhack - so I should be good with my installation? Sorry for all the questions, but I am very new to this and want to make sure everything is right before they close up the walls.

Anything else you suggest I do while the walls are open? I am considering running bell wire just in case I decide to add buttons down the road...

Thanks,
David

 

[breplum]

We have had a few calls over the years to replace non-sweep elbows that velocity-related eroded from constantly operating recirculation pumps (typically without aquastats).
Not likely an issue from properly small (like the Navien has) pumps with aquastats built in, but we always adhere to industry gold standard to use sweep elbows.

 

[Twowaxhack]

I agree longsweeps are better but I wouldn’t let it stop the job, especially if they are exposed where I can easily replace if there’s an issue.

Heres the one I’m talking bout. Check valve is bad. 3 short sweep 90’s all 12” from each other.
I might be replacing all of it tomorrow.

 

[SoCalDave]

Thank you, everyone. Does the Navien 240 have an aquastat? I don't see any mention in the manual. When internal recirc is on without intelligent preheating, is it always on, or does it use an aquastat to shut off at a certain temp?



Thanks!
-David

 

[breplum]

Yes, it most definitely has a temp sensor/aquastat.

 

[SoCalDave]

Thank you, @breplum. Is it settable? Or does it just keep the water in the line the same temp as the pre-set temp on the heater?

So, to clarify, if I turn on recirc but turn off intelligent, it will constantly keep the water at the preset temp?

Thanks!

 

[SoCalDave]

One other question - my kitchen and upstairs bathrooms are all within the recirc loop. I have one downstairs powder room that tees off from hot water before the return, so it is not part of the recirc. If I find that the time for hot water to that sink is too long, would it make sense to install a recirc pump under that sink? Just wondering what options I have for that sink. Thanks!

 

[breplum]

Generally, Navien tech support could run you through the process to set different return temperature parameters. I have spent no time drilling in to the newest v. with the multi line display, so don't know more.
We would have run the loop wider in case as you describe...no comment on any other solution like adding a pump.

 

[SoCalDave]

Hi all,

Our recirc line is complete. I turned on dip switch #1 (for internal circulation) but left #2 off so that it didn't use intelligent preheating - so my understanding is that with this configuration, it should keep the water at the preset temp all the time. I also confirmed that the valve in the 240 is set to internal recirc. The recirc icon is showing on the front panel and I hear the 240 fire up.

I then went to the furthest fixture (upstairs bathroom) and turned on the hot. Unfortunately, the time it took to get hot water seemed no faster than before without the recirc loop. I left and came back later and tried again, and it still took quite a while (a couple of minutes) to get hot water to the sink. It seems no faster than before.

Am I doing something wrong? Is there another setting I'm missing? I'm just a little confused since I thought the recirc would speed up the hot water delivery.

Thank you!!
-David

 

[breplum]

If recirc is running, the return is hot most of the time, so, feel it (at the WH)...it is working if hot.
If your branches off the trunk are long, then that is where your waiting time is.
Intelligent setting will learn usage and not run late at night if no use is detected.

 

[Twowaxhack]

Use high flow aerators