Homes that do not have a dedicated recirculation loop can be retrofitted with the Smart Thermostatic Control Complete System that consists of a Smart Controller, an AquaMotion AM5-SF1L recirculation pump and one or more AquaMotion AMK-ODR thermostatic valves. These valves connect the hot water line to the cold water line under the furthest sinks in the house allowing water to be pumped from the hot water line into the cold water line until hot water reaches the valve causing it to close. The controller senses when the flow stops and turns the pump off rather than allowing the pump to dead head against a closed valves like all other systems. You can see a video of the installation on YouTube.
The question always comes up, how many AMK-ODR valves do I need? Depending on how the plumbing is run in your home you may get better performance with multiple AMK-ODR valves under multiple sinks. To know how many valves you would want you can perform the following test. Allow the plumbing to go cold, so doing this first thing in the morning is good, and go to the furthest bathroom in the house and run the water until it gets hot. This will simulate one valve installed under that particular sink. Once you have hot water at that bathroom, go to the other bathrooms, kitchen and laundry room and run the hot water timing how long it takes for the water to get hot at that location. If you have to run quite a bit of water down the sink while waiting for hot water, it may be beneficial to install another valve at that sink location.
Another reason to install a second or third valve is if you have a large house. The AMD-ODR valves have the highest flow of any thermostatic valve on the market, but they still restrict the pump flow. So if you have two bathrooms that are near each other but far from the water heater, installing one at each location will allow twice the water flow thus speeding up your on demand hot water performance.
A third, but advanced trick for getting better on demand performance would be to plumb the AMK-ODR valve in behind the stop valves underneath the sink. The water is delivered to the sink through a ½” pipe, but the stop valves neck that down to 3/8” which significantly restricts the hot water flow. Installing a ½” T behind the valve directly to the ½” pipe and then plumbing the AMD-ODR valve directly to this T instead of to the valve outlet will allow greater flow through the valve. This technique requires turning off the water to the whole house and a little bit of advanced plumbing to remove the T that comes on the end of the AMD-ODR valve so it can be connected directly to the ½” T, but you may find it beneficial. The AMK-ODR valves do not have tapered thread so they must be connected with an o-ring or washer to keep them from leaking.