SmartPlus Recirculation

recirc3Hey Dave, Does the SmartPlus need any special piping at the furthest fixture unit?  Mike T, VT

Mike, there is “special” piping that is needed for the current application of the SmartPlus. Just like any other Taco circulator, it needs to move the water in a “circle.” If water comes into the SmartPlus, it needs to leave the SmartPlus. If there is no fixture open at the moment, the water won’t move and you would just “dead-head” the circulator. We don’t want to wait until a fixture is open, if we did that there would be no need for the SmartPlus, the water is already flowing. The SmartPlus needs a dedicated recirculation line in order to move the water. This can be done with smaller copper or even PEX tubing. Drop a TEE in the hot water supply as close as possible to the furthest fixture and return it to the suction side of the SmartPlus. This return tee does not need to be right at the furthest fixture, just as close as you can get it. If it’s three-quarters of the way there, you have eliminated the wait for hot water at the furthest fixture by 75%. And at all of the other fixtures before the TEE, hot water will be available immediately.

Hey Dave, How does the SmartPlus recirculation pump sense flow? Tom W, NC

smartplus controllerTom, the SmartPlus comes with a sensor that you want to strap on the hot water supply pipe coming out of the water heater. As soon as you power up the circulator, it’s in the learning mode. SmartPlus learns the hot water usage in the house for 7 days. The initial 7 days the system is powered, the SmartPlus will pulse the pump for 2-1/2 minutes every 10 minutes. While in this learning mode, SmartPlus is looking for a rise in water temperature, a steady temperature, and then a degradation of that water temperature over a period of time. For example: taking a shower or running the dishwasher would constitute a rise and then a steady temperature. A quick washing of hands is not recorded because of the short amount of time. Once this is recorded, SmartPlus expects this event to happen again 7 days from now. So let’s look at typical hot water usage in a home. Every morning someone’s using the shower at 6am, Monday through Friday. There is a second shower taken at 8:30 am, Monday through Friday and dishwasher usage at 7 pm, Monday, Wednesday, Saturday and Sunday. All of these events are recorded and the following week, the SmartPlus will anticipate these events and turn the circulator on one hour before the event and continue for one hour after the event. It does not run continuously for that time period, it is running for those 150 seconds every 10 minutes.

If there is no use of hot water for 36 hours, SmartPlus goes into “vacation mode” until there is another event and then the schedule starts up again. If you need more information on the SmartPlus or any other recirculation product, check them out here.

Excellent guys, I hope this helps everyone out there and keep ‘em coming

Dave H.

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14 Responses to SmartPlus Recirculation

  1. carl perrone says:

    Good stuff Dave!
    Thank you,

  2. Eric says:

    Hey, thanks for the information about short draws not being counted as part of the “learning” process – that was one of my questions. We just spec’d one of these pumps for a model, and I actually plan to put some temp sensors on my DHW system (once we get into the house) and see how this thing works in real life.

    I don’t suppose the firmware is field upgradeable? 🙂

    • davidholdorf says:

      The firmware is not upgrade-able in the field except for changing the controller. Why do you ask about upgrades in the programming?

      • Eric says:

        No real reason – only because I’m a software developer, and I know bugs can exist. 🙂 Just thinking ahead a bit. I’m excited to see how the pump works in practice when we get back into the house at the end of the year!

  3. Pingback: Getting into hot water, fast! | Eric's Blog

  4. Charly says:

    Can I put pipe insulation over the temperature sensor or leave that section of pipe un-insulated? I’m wondering if the insulation would “confuse” the sensor by slowing the temperature drop.

    • davidholdorf says:


      For such a short piece of insulation, it wouldn’t confuse the the sensor. The logic in the SmartPlus is not reading the actual temperature but rather reading the usage of hot water. It looks at a temperature rise, a duration in usage, and then a temperature drop. Insulating will not affect performance of recording the events.

      • Charly says:

        In understand what you’re saying, but I still wondered if the pipe insulation would slow the temperature drop that you mentioned and that this would confuse the usage logic.

        Another question: Once the 7 day cycle is recorded, will it auto-adjust over time if our usage patterns change substantially? If not, I’m guessing that I can simply pull the plug and plug it back in to restart a new 7 day learning cycle.

      • davidholdorf says:

        Pipe insulation would obviously slow the temp drop but would not confuse the logic. When it records an event, the operation is one hour before the event and one hour after the event, It does this because not everyone’s schedule is exact to the minute everyday and adds flexibility. As for your second question, once the 7-day schedule is recorded, it still learns on a daily basis. For example if an event is recorded on a Monday at 7am, the system will turn on a 6am the following Monday. If the event is not done in that 2 hour window but now at 10am, this is the new time it will operate the following Monday. So you do not have to power it down/up in order to learn a new schedule.

  5. Eric says:

    Hey Dave – so I finally got around to putting some temp sensors on my system and doing some logging to see how things are behaving. And I was surprised to see that my Smart Plus is only “sleeping” from about 2am to 4am – and running for the other 22 hours of the day. Granted, this is coming off a week of Christmas guests, which might not be the most typical week of usage. But if the Smart Plus tries to pump 1 hour ahead & behind of anticipated usage, I’m surprised to see it start up at 4am!

    I’m currently logging temperatures on the return side near the pump, and on the tank cold water inlet – I figured that I could see temperature drops there which would indicate draws.

    But this also makes me wonder – if my pump is running 22 hours out of the day, how can it hope to differentiate between outlet temperature jumps from hot water draws, vs. jumps due to the circulation pump running?

    Anyway, I’ll keep an eye on it during the coming, more “normal” weeks. If your engineers are interested in any field data I’d be happy to share it. 🙂


  6. Barry says:

    Does the vacation mode work while it’s on pluse mode?

  7. Mel says:

    How do you turn off the error without unplugging the pump? The sensor got momentarily unplugged and the sensor led is flashing all the time now.

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