External vs Internal Recirculation:

[Stan G]

Newbie to on-demand condensing water heaters just bought a newly-constructed house containing a Navien NPE 210/240 A. Valve is set to Internal. Switch 1 is ON; all the others are off. Heater is in crawl space SE corner of house; master shower is 2 floors up in NW corner. It takes 3 minutes to get hot water to the shower. I don't know whether a dedicated recirculation line has been installed. I do have an expansion tank but that is a code requirement in BC and therefore doesn't give any hint about the type of installation. There is no external pump visible. (see photo of installation). I've read both installer's & user's manual and every Navien-related post in this forum and am still unclear about the basics. Please explain in layman's terms the route of hot water flow in external recirc. & in internal recirc. What are the advantages and disadvantages of each? To date, I've raised the temp from 120 to 130 degrees and I've tried to turn the 2-way valve dial from Internal to External by hand prior to changing the switches to 1 OFF & 2 ON, but the valve dialView attachment 56871 View attachment 56871 View attachment 56871 doesn't move. How much force can I apply without damaging it?

Regardless of the type of recirculation chosen, is there any reason (other than minor added water & gas expense) to open a hot water tap just a bit before turning on the high efficiency washer that also came with the house, and leaving it trickling until the wash is done? I'm more concerned about the longevity of the hot water unit and the expense of repairing/replacing it prematurely than I am about minimizing energy costs.

 

[Aristoc]

Do you have a 210 or 240? The A model has that round pump inside. That is an internal pump. It doesnt look like you have a external pump connected because your Navien already has an internal pump that can be used to circulate water around externaly that it, from your fixtures which are all external . You have an internal pump but your are circulating water externaly. That red tube coming down on the left looks like it is an external recirculation line. Water is coming in from your fixtures in that tube. That two way lever valve should be set to external to let the water in. I wouldn't bother setting the temp higher than 120 degress. You should set up your Navien for external recirculation using the internal pump. That round pump will circulate water around and around all of your fixtures keeping warm water nearby when you need it. How often does it circulate around and around? Depends on your settings. You can set it so that it automatically recirculates when the temperature of the water begins to drop. The burner will fire up and rewarm the water. It will keep doing this automatically over and over again 24 hours a day. Or you can set it so that the Navien learns your habits and only recirculates based on the Navien learning your habits and sort of programming itself. Like if you wake up at the same time and shower every morning at the same time the Navien will pre-heat and circulate all that water ahead of time.

please double check the manual but for constant regular recirculation of heated water : you should have 1 OFF 2 ON 3 OFF If you want the Navien to learn your schedule than you can set 1 ON 2 ON 3 OFF.

 

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[BradD]

Hello Aristoc - thank you for the info that you provided, that was helpful. I flipped the dip switch 1 to ON and it seemed to help me get hot water faster to my upstairs sink/shower. I have a couple generic questions I'd like to ask:

1) Now that I finally turned on recirculation switch, do I need a bridge valve at furtherest sink upstairs? I've read several times about installing a bridge valve, but am unsure if it's needed.

1) I have seen in other forums/videos that when the home owners first installed the tankless water heater, everything was working fine, and he got continuous hot water. But then when his kids got older and started using more water, the kids would have to wait for hot water (their room was a little further away I believe). So does that mean that the standalone tankless water heater only works well when there are only a couple people using hot water? So if there are multiple people using water, then an external recirculation pump is needed? Or is it a distance thing?

Do you have a 210 or 240? The A model has that round pump inside. That is an internal pump. It doesnt look like you have a external pump connected because your Navien already has an internal pump that can be used to circulate water around externaly that it, from your fixtures which are all external . You have an internal pump but your are circulating water externaly. That red tube coming down on the left looks like it is an external recirculation line. Water is coming in from your fixtures in that tube. That two way lever valve should be set to external to let the water in. I wouldn't bother setting the temp higher than 120 degress. You should set up your Navien for external recirculation using the internal pump. That round pump will circulate water around and around all of your fixtures keeping warm water nearby when you need it. How often does it circulate around and around? Depends on your settings. You can set it so that it automatically recirculates when the temperature of the water begins to drop. The burner will fire up and rewarm the water. It will keep doing this automatically over and over again 24 hours a day. Or you can set it so that the Navien learns your habits and only recirculates based on the Navien learning your habits and sort of programming itself. Like if you wake up at the same time and shower every morning at the same time the Navien will pre-heat and circulate all that water ahead of time.

please double check the manual but for constant regular recirculation of heated water : you should have 1 OFF 2 ON 3 OFF If you want the Navien to learn your schedule than you can set 1 ON 2 ON 3 OFF.

 

[Fitter30]

All condensing water heaters are rated at a particular incoming water temperature, out going temperature and gpm. If you have a big soaker tub ,shower with multiple heads or running multiple items. Need to do some home work find out whats the coldest incoming water temperature, temperature rise and gpm. Install manual should have the temp rise to gpm. Shower heads and tub spout 5 gallon bucket and a watch to time how fast it fills. Once water starts flowing over .5 gpm heater will come on.