How is the Taco SmartPlus recirc pump working in my house?

The Taco SmartPlus hot water recirculation pump is designed to push domestic hot water around a recirculation loop, so that hot water is at the taps when you want it, saving time as well as water down the drain while you wait.  It’s designed to learn your schedule, to avoid energy losses associated with pumps that run 24 hours a day, due to both the electrical energy used, and the lost heat in the loop when there is no hot water demand.

The SmartPlus pump is supposed to be “smart” in the sense that it uses a temperature sensor on the output of your water heater to learn when you use hot water, and adjust its run schedule accordingly.

So I had to find out, “is our smart pump learning?”  And so far, I have to say it’s not. (edit: I think power loss to the pump is the reason, read on)

smartplus_electricityAbove is a graph of the electricity used on a circuit dedicated to the water heater and the recirc pump.  As you can see, it’s got activity at all hours of the day.  (The weird modulation is because the pump runs 2.5 mins on, 10 mins off, and the datapoint averaging wasn’t lined up with 12.5 minute periodicity…).

During the same time period, here’s the temperature on the water heater output (Ignore the fact that it says input, I mislabeled it) :)

water_output_tempIn theory the pump works by detecting a sustained rise in temp, indicating a hot water draw.  It must have to notice this during its 10 minute non-circulation phase, because when it’s circulating, it’s causing the temp rise on its own.  I have to admit, looking at the graph doesn’t make me feel any smarter than the pump.  There was a rise around 7am; that was a shower this morning.  The rise later in the afternoon I can’t explain.  The big dip last night was an unnamed person using all of the hot water, so the output temp dropped due to that.  All the little sawtooth bumps are due to the pump circulating water, and drawing up more heat.

At least the pump’s “pulse” operation (running 2.5 mins on, 10 mins off) cuts down on electrical energy use compared to a pump that runs constantly.  When running, it uses 55W in my system.  It pulses about 155 times per day for 2.5 mins, so runs about 5 hours per day, not 24.  That ends up using about 8kWh/month.  If it could smarten up a bit, it’d use less!

edit: Now that I’ve RTFM’d again, I see that power loss causes the pump to start its learning cycle all over again, and “pulse” for a week while it learns.  And in my fiddly nature, I’ve dropped power to i.e. set up the monitoring.  So perhaps I’m not giving it a fair shake.  I promise to leave it alone for a week, and report back!  Still, with the giant capacitor in the unit, I’d hope it could survive a brief power loss.  Oh well.)

FWIW, the graphs above are from xively.com, with data pushed there from a Brultech ECM-1240 electricity monitor and Matthew Wall’s mtools scripts, as well as temperature data fed from an Electric Imp.

17 thoughts on “How is the Taco SmartPlus recirc pump working in my house?

  1. I was intrigued by your post. Following the link, I downloaded the manual for the Taco device @ http://www.taco-hvac.com/uploads/FileLibrary/102-475.pdf

    It appears there are two modes selectable by switch: Pulse mode and smart mode. You seem to be describing pulse mode with the 2.5 minutes on and 10 off. The learning mode requires the switch to be in the other position.

    I wonder what the results would be with the switch in the other position.

    • Yep, it does have those two modes – but I opened it up and confirmed that the switch is in the “smart” position. (I think even in smart mode, it does do the the 2.5 on / 10 off cycle during the “active” periods).

      The pump will run in “pulse” mode from 1 hour before to 1 hour after each recorded hot water demand.

      So I think it’s in smart mode, it’s just not being very smart yet!

      p.s. the other thing that’s kind of funny: it says that it runs for “150 seconds every 10 minutes” – which would imply 2.5 mins on, 7.5 mins off. But that’s not what it does; it’s 2.5 mins on, 10 mins off. I’m assuming that’s a programming error, which makes me a bit more skeptical of the rest. :)

    • But – thanks for pointing me to the manual again. I had somehow glossed over the fact that a power loss causes it to go back into learning mode for a week. Unfortunately I dropped power to set up the monitoring, and dropped it again today before I opened it up to check the switch. So I need to leave it unmolested for a week, and see how it does. Check back next Wednesday, I guess. ;)

    • It’s in Degrees F, but it’s an uncalibrated temp sensor, not terribly well coupled to the outside of a pipe – so I think it reads quite low. The water in the tank is around 120F/50C or a bit higher, which suffices, I think.

  2. Hi Eric,

    Why not just use an on demand switch (z-wave, insteon, etc) in each bathroom to turn the pump on for a few minutes when you need it?

    I went that route and saved about a lot of $ in gas and electric bills with our reciruculation system vs the 15 min on/off timer on the grundfos pump we have (granted your pump sounds much fancier)…

    Just a thought; the only down side is we have to wait ~1 minute for water but no wasted water down the drain.

    Steve

    • Hi Steve –

      Yes, I thought about that; there are pump kits from Taco which are designed specifically to work this way (with higher velocity pumps, I think). I liked the purported high-tech/smart nature of this pump, and wanted to give it a try. I could revert to a remote switch with this one too, actually, if it turns out to not be so smart. But so far it looks like it’s actually starting to do more or less the right thing now.

      It probably does use a bit more energy than your switch arrangement, but so far I like the convenience of the thing.

      Thanks!
      -ERic

    • Can you tell me a little bit about your setup. My remotes for my d’mand system are all dead and I wanted to implement exactly what you are talking about but no one I’ve asked has been able to help.

      Thanks!

      • Well, this device from Taco is supposed to Just Work. If you look at the docs for it, they explain how it is designed to sense hot water use, learn the schedule, and automatically run only at those times. At least in my household, this didn’t work – we had so many periods of use that it ran almost all the time in “smart mode” so in the end, I simply put it on a timer, I’m afraid.
        There is another pump from Grundfos which claims to do the same learning; I don’t know if it works any better than the Taco.

    • I’ve thought about that as well; I do think I could probably do a better job than the pump’s firmware.
      If nothing else, I’d like the ability to “learn” but also set time periods when it should simply never run; say, 1am to 6am. Sometimes this pump does, because it runs for 1 hour either side of a “use” and that tends to make it run more than I’d like, and spill over to hours when it has absolutely no need to run …

    • I haven’t really distilled the data; I do have electrical data for runtimes, as well as lots of temperature data showing when we have hot water draws. My overall impression is that the pump runs quite a lot; it seems to err more on the side of “keep hot water going” and less on the side of “save energy.”
      I’m on the verge of disabling its smarts, to be honest, and just putting it on an outlet timer.

  3. I have a long run for my water and am only in my house every other week. The smart mode ( week of learning followed by a week of similar activity is a disaster for me) the 2.5 minute pump followed by 10 doesn’t seem to keep water hot all the way through the pipes. 5 min hot shower followed by 15 minutes of Luke warm water followed 15 minutes of good hot water followed by 15 of Luke warm until I just gave up. It’s been on for four weeks.

    • I can see where a week home / week gone schedule would really not work. You might consider just putting it in manual mode, and putting the whole thing on a timer? I’m surprised that the 2.5 minute pulsing doesn’t work, though – is your hot water run (and return piping) insulated?

  4. I have the same ‘smart mode’ problem with this Taco pump. A recent energy audit showed that my circulator was going on in pulse cycle 24 hrs a day sucking cooler water into my tank which then turned on my tank heater. My lines are all insulated but I was using 1600 Kw/month (instead of the tanks rated 5160/year).
    Switching to the POS Taco circulator and will report back on the results.

Leave a Reply

Your email address will not be published. Required fields are marked *