Ideal in concept, flawless in execution.

The key issue of having a hot water loop system is how the system “knows” when you want hot water so it can trigger the pump. I’m familiar with several ways to do this:
*Manual switch at the pump
*Timer at the pump
*Remote buttons at bathrooms or sinks (wired or wireless)
*Sensor on bathroom doors (turns on when opened)
*Motion sensor in bathrooms or kitchen
*Motion sensors under the cabinet toe kicks

But there is *already* a mechanism by which the system knows you want hot water: when you, from a faucet, run the hot water. This system eliminates all timers, switches, motion sensors, etc. by this simple yet profound observation, replacing them with a much superior sensor – a flow meter on the water line going into your hot water tank.

Additionally, this system also supplies timely hot water to other fixtures that aren’t normally served well by timers, motion sensors or door sensors: the clothes and dish washers. Anything using hot water can trigger this system.

Additionally, it knows when to turn the pump off. This is critical for energy and water savings. The pump can only bring the temperature of the hot water loop up to within a few degrees of the water in the tank. Once that occurs, the pump should be shut off. It is not as simple as checking the water temperature in the loop for a static target temperature because as hot water is used from the tank, the temperature can begin to fall and the pump wouldn’t turn off until the hot water usage was stopped and the hot water heater recovered (which is harder for the hot water heater to do while the pump is on!). So this system monitors *two* temperatures – the hot water leaving the tank, and the hot water returning to the tank from the loop. The two temperatures are used to calculate a the temperature *difference*. Once temperature in the loop is within a few degrees of the tank, the pump is automatically turned off until the temperature difference increases *and* usage of hot water continues. ALL of that is exactly what this system does.

The result is that the pump runs exactly when you need it to, but not a minute more. And the homeowner experience (my family and I) is sublime. I both have hot water when I want it AND save money not running the pump too much or too little. Running it too little results in hot water users running water down the drain. Keep in mind that as a user runs water from the hot faucet down the drain, even if it’s cold, cold water is running into your tank, cooling it down.

If the hot water loop is completely cold – like early in the morning when all night long its saved you money by not running the pump and by conserving hot water – I simply turn on the hot water faucet for literally slightly less than a second on my way toward more pressing needs. By the time I’m ready for hot water on a cold winter morning, it’s *right there*.

For those that just absolutely need the hot water pump run at a specific time, you’re still covered. The app allows you to program several run times if you wish. Personally, even though I get up at a regular time during the work week, I *still* don’t use the timers because the flow meter is such an effective mechanism to indicate hot water demand.

Every house with a hot water tank should be built with a loop and the pump controlled this way.