Smart Hot Water Recirculation Solution

First let me say thank you to everyone here for working on this issue. This is going to be my next project that I do with SmartThings and the community experience shared here is invaluable.

In researching parts and what-not I found this little beauty. It uses the DS18B20 so it should simply be a matter of wiring the appropriate connections. Perhaps into one of those cheap Sonoff TH10s as per this thread.

I’m also attracted to this pump. It’s a bit more expensive than the Bacoeng, but it looks right for my purposes (dedicated return line). My only concern would be physical support for the pump since all my plumbing is PEX, but I’m sure I can figure something out.

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Neat DS18B20 sensor package. I think that is more in line with what @wgmcg was looking for. I don’t know that it would perform any better than a TO-92 package but it would certainly look nicer. Brewers have all the toys! Be careful about mixing metals and galvanic corrosion. PEX and stainless steel should be fine.

Sonoff vs. Fibaro seems be an integration headache vs. cost tradeoff. Flexibility vs. simplicity. Clunky vs. cute.

Good luck with your project!

Oh! That sensor is the sh*t!!! Yeah, looks like it’ll require a stainless female 1/2" pex barb, 1/2" npt, 1/2" pex barb fitting for my setup. I hope such a fitting exists.

The little sonohff device is cool too.

As for the pump? It looks pretty solid at a good price point, but what are you trying to achieve? The flow/head ratings look a little anemic for my purposes. Looks like about 3.5 GPM at 3 ft/head but maybe I’m reading the wrong chart. Are you trying to do a continuous loop or on demand?

In my case I’m looking to heat and move water to the fixture in as short a time as possible. The bacoeng at the highest setting can get this done in 30 seconds or so. The Watts pump took more like 90 seconds with similar specs to the Laing.

I found a tee and barb fittings in 316 stainless steel on Amazon. Can’t find it in 316 in less than packs of five. 304 would probably be fine, too, but why not go for the best? :slight_smile:

I’m going for an on-demand loop, so perhaps a more powerful pump would be more appropriate.

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@wgmcg I see the Watts pump says not to be used with tankless water heaters. Not sure why.
You haven’t had any issues?
I don’t have a tankless but want to upgrade to one once my heater fails. (We actually are supposed to replace them every 10 years or insurance will not cover any flood damage caused by them failing but very few people do or even know about the 10 year limit).
Want to make sure I get a pump that will work with both a tank and tankless system or do tankless have pumps built in and not require a pump?

I returned the watts pump to amazon, but I did try it out with my tankless and it worked ok. Again, the flow rate was a little low for an on demand situation.

I think they say not to use it with tankless for a couple of reasons. The first being that it may not have enough flow to trigger the tankless, though it worked ok in my case with my rheem.

The second case is that as a timer based pump it could potentially cause your water heater to fire excessively.

Most tankless water heaters do not include a recirc pump, though it is becoming more common to include one, or offer one as a field installed option.

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how loud is the BACOENG pump you got?

Not very loud once you get the air out of the lines. Standing next to it,
you’d have to know what to listen for to know it’s on.

What did you end up using for reading temperature?
were there any issue (excess water flow/pressure) if someone turned on a tap while the pump was still running?

For reading temp I’m still using the Fibaro FGK-101 with a ds18B20 glued to a section of copper pipe.

I’ve bought the parts to replace the sensor with the BrewPi one mentioned above, but I haven’t installed it yet.

One problem I’ve had with the Fibaro is that the batteries haven’t lasted well with the activity that the sensor is seeing, so along with installing the new sensor I’m going to hard wire the fibaro to usb power, also as mentioned somewhere above. I just have to find the time to do the project.

The fact is the recirculator works fine without the temp sensor. I just have the pump run timed in my piston to run for 30 seconds at no less than 15m intervals when there’s motion in the bath. It’s slightly less efficient I suppose since the pump runs regardless of the water temp, but its really not that bad. I have a fuel stream that tracks the pump runs and it runs between 12-18 times per day for 30 seconds. So lets say 9 minutes/24h for nearly instant hot water every time?

I use the 2 pistons above in the thread, plus I have another failsafe implemented as a smart ligthing app that turns the pump off if the “power allowance is exceeded” and its been running for 1m. My hope is this catches a condition where the pump is on and ST cloud goes down, since Smart Lighting, and my zwave switch both run locally, but I haven’t fully tested that either.

As far as flow issues with the pump on, I haven’t seen any. I haven’t noticed any pressure differences with the pump on or off.

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thanks good to know
I am thinking to just install a smart switch for the bathroom light switch
and a smart electrical outlet at the pump. Then have the pump turn on for
approx 30 secs whenever the bathroom light is turned on.
Not exact but should work save messing around with the temp. Was thinking
of using the motion sensor but sometimes go in just to grab something but
we always turn on the lights if using the shower/bath.
My biggest issue will be running a return line back down to the basement
not keen on running back through the cold water line but if I have to then
will just put in a EcoNet EBV105 valve control.

Whats the EcoNet valve for? To shutoff return to the cold water line when temp is reached?

yes pretty much.
If I can not get a hot water return line back down to my water heater then I will plumb a connection from the hot water line (at the farthest point) to the cold water line with a hand lever valve in between and put the EcoNet Control EBV105 on the hand lever valve handle and set it to cycle open and closed with the pump turning on and off.
You could use it with the temperature as well but I will likely try the whole setup without using temperature control so it only activates when I want it.

There are a couple of other similar devices to the EBv105. I have the
"dome" from amazon which is about $99 mounted on my main water shutoff. The
Topvico, Xenon, and Jinvoo valves look to be nearly identical, but are only
$69. The only differences between any of them appears to be the mounting
setup, the motors all look the same.

One thing about these valvebots is you have to be careful to align the axis of
the motor EXACTLY over the axis of the ball valve or they won’t close or
open all the way. Also I don’t think they would work on pex very well, so
you’ll have to put in a well secured piece of copper on either side of the
valve to mount the motor on.

waiting for my pump to arrive
for dual purpose leak detection and temperature sensor and can be hardwired to a electrical plug in so constant power?
Don’t have one yet and not sure where it pulls the temperature from if it is from the leak sensors probes or just ambient.

The device has built in temperature sensor that allows to monitor ambient temperature.

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thanks for the info I didn’t see that
I wonder though if the flood sensor is using a DS18B20 inside as engineers usually stick to what they know.
If so it would be easy enough to modify and do what you did in the original post.
I ordered 2 of them (one for the basement and one for the far tap) as I like the always powered on hardwired feature worst case I end up with 2 more good leak sensors.

finally finished my hot water recirculation.
I could not use the temperature from the Fibaro FGFS-101flood sensor but atleast I have a hardwired flood sensor.

I used

  • a EcoNet Control EBV105 valve at the farthest sink from the hot water heater to direct hot water back into the cold water line. It says it will fit on 1/2 inch valves but as @wgmcg noted it did not fit on 1/2" pex lines. Luckly I had another 3/4" valve and 3/4" to 1/2" adapaters which fit fine with a piece of 3/4" pex. The new EcoNet bulldog valve may work better or the dome as they have different mounting.
  • the BACOENG pump down at the hot water tank outlet with a couple of ball valves on either side in case I have to swap it out and a Fibaro Z-Wave Plus Wall Plug FGWPB-121 to control it.
  • for temperature control I used Qubino Z-Wave Plus On Off Thermostat Module ZMNHID3 and a small plastic case I got from the local dollar store. I also had to order a 24 volt power adapter from Amazon (odd that it is 24 volt).
    zip tied (might have to secure it differently if the zip tie does not last) the sensor to the valve and noted the temperature range. Then set a condition not to operated if above a set temperature.
    (probably cheaper to do what @rossetyler did and modify it for a plug in power source)
  • I also installed a smart switch for my bathroom lights
  • now when the bathroom lights are turned and the temperature on the valve is below a set amount (in my case 30 degrees celsius) on the valve. The valve will open and the pump will come on and then turn off when tempature is above the set point and the valve will close.
  • I also added a condition that the pump turns off and the valve closes after 40 seconds or the light switch is turned off as a safety (in case the temperature probe got knocked off or stops reading)

thanks for all the info and ideas
you cost me a lot of money


I’ve finally gotten around to trying to hardwire the Fibaro FGK-101 to usb power, and wire up the brew pi sensor to it. I’ve been putting it off for several months because I knew how much the whole project was going to SUCK, and it hasn’t disappointed on that score.

I’ve got the blue light coming on on the FGK-101 and I can add it to my ST system as a fibaro device without temperature, but as soon as I switch to the temp driver it dies. Nothing works anymore, even the contact sensor breaks.

I’m trying to wire the brew pi sensor in with a phone jack, and I think what I’m assuming is the pin out (straight through) is incorrect. There’s no documentation from brew pi as to which wire goes to which pin so that could be the problem, or it could just be that the Fibaro device is flakey AF, which it is.

I guess I’ll drop an email to brew pi to see what the pinout on their device is, because assuming straight through doesn’t seem to be working.

USB power is 5 volts. The Fibaro FGK-101 uses a 3.6 volt battery (probably needs 3.3 volt +/- 10%).