It looks like it's just low voltage wiring (eg. phone line wire, doorbell wire, etc) that goes to the 'hot button' so you can really put it anywhere. The cabinet door is kind of misleading because you'd assume that there'd have to be a little cable dangling somewhere, but they photoshopped it out.

But this brings up a question in my mind (a little off topic). What's the point of having a re-circulation loop that you have to manually turn on? Isn't the point of a re-circulation loop so that you don't have to wait for the hot water to show up at the faucet? If you have to manually turn it on, then you have to wait until the hot water has been circulated.

I guess it saves that little amount of water that would normally go down the drain while you are waiting for the hot water. Is that what you're trying to save? Not time, but water?

Yeah, it only saves water unless you've set the pump to recirculate on schedule in which case it could also save energy.

The company sells something call Navilink that let's you control the pump (and other features) with a smartphone app. Can you imagine having to remember to use your phone before you went to the bathroom or took a shower?

Brother has that, he uses a timer and a button in the laundry room, in a cabinet.

Their kitchen is close to the heater vs the bathrooms, so timing was easy to determine.

Thanks everyone for your comments. (And thanks Greg for confirming I’m not crazy since I didn’t see a wire and....it just seems odd on the back of a door). Yes, I want to save water. I live in CA and in past years we’ve had water restrictions. I‘ll be waiting for hot water to arrive, whether the tap is running or not. Also, someone I know says she can hear hers when it’s running on schedule. Why listen to it heating water that I don’t need? Plus, as Lawrence pointed out, I‘d save energy vs. the scheduled recirc. FWIW, I had assumed that I could schedule and have these buttons supplement it but when I was researching yesterday, some website said it was an either/or thing. Seems like very poor design. Maybe they fixed that. I guess if I hate the buttons I could always use the schedule feature like normal people. ;)

Jake, were you joking about motion detector? I.e. every time I walk into one of those rooms it would kick on, even if I don’t need it?

Lawrence, funny you should say “Can you imagine having to find your phone...?” Yes, I did try to imagine it LOL and thought low-tech was the way to go (as long as I could hide these buttons).

Another aside: my plumber offered the option of installing a water softener. I don’t like soft water. So I’ve been researching other options to avoid the mineral build up. My thoughts: flush regularly (maybe more often than recommended). Also, use this hot button so I’m only heating the water I actually need to be hot. So I guess I’d be using this as a whole house water-on-demand system. Maybe I’m weird (?)

Ok, I’m confused. We had the Navien installed about 6 months ago. It already has a recirculating system built in. The installers couldn’t get it to work with the recirculating system we already had in place.

clt3, what do you mean by your existing recirculation system, another recirc pump? Not sure you need two, if your new heater has one built in. What was the solution--just use the Navien? Sounds like it's working.

Just talked to Navien tech support. FYI if anyone is interested. I had multiple concerns:

a) avoid using a water softener:

--he recommends flushing after a year to see how much sediment comes out and determine if I need to flush more or less often; there is no other scale indicator

--a sediment filter or any filtration system could help

--there may be some negligible reduction in scale build up if I set the water temp lower (default 120 degrees; lowest setting is 110). There may be some negligible reduction in scale by using the "hot button." (since the hot water is recirculating, theoretically it's not adding much more scale if it needs to get reheated a bit on each loop). The "hot button" can save energy of re-circulating the water. (though the device is energy efficient)

b) hot button wiring

--yes it's like a doorbell wire, low voltage, can be mounted anywhere

--he volunteered that some people use motion detectors; they don't sell them

Thanks everyone for your help!

Bumping my own thread.

We’re getting ready to install the “hot button” on the vanity. Did anyone do this and come up with a clever location in the bathroom. The button is about the size of a dime and low-voltage so it can go anywhere. Plumber suggested drilling a hole in the side of the vanity but I was thinking of tucking it inside the vanity door or ? (Or maybe under the lip of the counter. I could push it...like a bank teller who gets a stick-up note, lol)).

BTW, I’ve decided agains the motion sensor. I don’t need hot water every time i walk into the bathroom—mostly just for showering. And yes, I want to save the water (I live in a state that has droughts) and the energy of the recirc pump. Why have it run when I don’t need it?

Thanks In advance for your help! I really appreciate it.

girl_wonder and others...

We're considering a Navien NPE-A2 which includes the built-in recirculating pump. We will be installing 4 HotButtons. We want to disable/override the "learn" and "schedule" modes. I called tech support this morning. They indicated the system will work with 4 buttons. I was not convinced that I can disable/override the learning and scheduling features.

What has been your experience? After one year of service has the HotButton feature worked like you expected? I presume you found suitable places to locate the buttons in the house. Other comments?