Demand-Sensing Hot Water Recirculation Control

Smart Aquastat Recirculation Pump Control for Homes with a Dedicated Recirculation Loop


Smart Aquastat Control - Demand Sensing hot water recirculation control

The Smart Aquastat Control 32 is an “on-demand” smart hot water recirculating pump controller for homes with tankless water heaters and a dedicated recirculation loop. If you don’t have a dedicated recirculation loop check out our Smart Thermostatic Control

The Smart Aquastat Control differs from the Smart Recirculation Control in that it has only a single temperature sensor and turns the pump off when the single sensor reaches the configured temperature rather than run the pump until the temperature difference between the water heater outflow and the return line are within the defined tolerance.

It is designed to sense when hot water is drawn from any plumbing fixture and to run the recirculation pump until the water in the recirculation loop reaches the programmed temperature. The microprocessor-based design monitors the temperature of the water returning in the recirculation loop to ensure the water in the loop stays hot while hot water is being used. 

The Smart Aquastat Control will work with all types of water heaters but was specifically designed to work with tankless water heaters.

While tankless water heaters are good at producing a never-ending supply of hot water, they are only capable of increasing the temperature of the water at a certain rate. 

Even the large 200k BTU units, for example, are only rated as being able to increase the water temperature by 40F° at 6 GPM or 80F° at 3GPM. So if you are starting with 60°F water, you can get 100°F water at 6GPM or 140°F water at 3 GPM (this is just an example, home water heaters should never be set higher than 120°F to avoid scalding issues). 

But if your hot water line has sat and is cold and you want to get hot water out to your fixtures quickly your recirculation loop may employ a 12 GPM pump which only allows the heater to produce a 20F° rise in temperature. So the first time through the temperature will increase from 60°F to 80°F and on the second pass from 80°F to 100°F. 

The ultimate solution to this problem is to install a small 5-gallon tank water heater after the tankless water heater. Not only does this provide an immediate supply of 120°F water to recirculate, but it also acts as a buffer tank for the tankless water heater to eliminate the dreaded “cold water sandwich.”

Barring that, the best solution is to use the Smart Aquastat Control as it runs the pump until the temperature of the water at the end of the recirculation loop reaches the controller temperature set point.

how smart on demand hot water controllers workTo operate go to any faucet and turn the hot water on, then off.  The Smart Aquastat Control senses this minimal draw checks the water temperature in the loop, and if necessary, starts the pump running.  Within seconds the water loop is hot and you are able to draw hot water. 

Because the Smart Aquastat Control uses the demand of hot water to know when to run the pump, it works even when your washing machine or dishwasher needs hot water. 

Unlike other on-demand hot water systems, there is no need to install switches or sensors at each faucet location and run wires or maintain wireless transceivers.  

The Smart Aquastat Control also has a set of Smart Timers that can be used to heat the recirculation line on a schedule. 

The Smart Controller only runs the pump until the line is heated up to the programmed temperature.  

Of course, outside of the timer periods, the controller will still run the pump on demand.

The “Smart Timers” are disabled if the controller doesn’t sense a hot water draw within 24 hours.  So if you go on vacation and forget to manually disable them, no worries, they will turn themselves off and re-enable as soon as it senses a hot water draw.  The “Smart Timers”  are set via your Android or iPhone smart device.

Leridian Dynamics also makes a LEED for Homes v4 compliant on-demand Smart Aquastat Control 32.


Based on 3 reviews
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  1. Mark S. (verified owner)

    Just installed device. Seems to be working as expected.Solved a problem. Glad I found this product.

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  2. Chris M. (verified owner)

    This is the best controller on the market, and it took me months to find it. We had previously had a recirculating pump and controller and loved it. An unrelated accident killed the controller, Original manufacturer was out of business. So trying to replace it I had some very specific things I wanted it to do.I actually came across “Smart Recirculation Control” and had e-mailed the company to see if they could customize one of there controllers. To my surprise I received an email back the next day they had a controller that already did what I wanted and more. I had just missed it as they make several controllers for different solutions. This controller gives you truly on demand control as wells the ability to schedule many timer controls. We love it!

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  3. John G. (verified owner)

    simply outstanding

    Smart Aquastat Control 32Smart Aquastat Control 32