Leridian Dynamics Inc. is proud to announce the release of a LEED for Homes v4 compliant version of the Smart Aquastat Control. The control comes configured by default to perform to their current exact specifications but the parameters can be modified via the smart phone app if the specification happens to change or the performance of the system does not provide adequate comfort. The following is the section of the LEED for Homes v4 specification that regulates recirculation pump controls.
Paths 1 and 2, Pumps and Controls for Hot Water Circulation Loops
Circulating systems must meet the following requirements.
There are many different recirculation pumps on the market and it can be quite confusing to know which one to choose for your recirculation system or even if the pump that you currently have installed is adequate. Because our controller is designed to run the pump only when you demand hot water, having a high flow pump is important to provide adequate responsiveness and comfort. It is for this reason that we recommend a pump that will flow 15 - 20 GPM. These are generally 1/12 HP pumps. We sell a pump that meets this criteria called the AquaMotion AM5-SF1L. This pump is rated at 18 GPM and 1/12HP and is adequate for most homes. For larger homes or homes that have a 1" recirculation loop installed or for people who just want the best on demand performance we recommend the AquaMotion AM10-SF1L. This pump is rated at 31 GPM and 1/8 HP. All AquaMotion pumps are designed and manufactured in the USA and come with a 3 year warranty. These pumps require a flange kit which is included in the price (specify 3/4" or 1" when placing your order) and they come with a 10 ft. electrical cord.
If you already have a pump installed and are wondering if it is adequate, look on the pump for the rated wattage. If it is less than 50 watts then it will probably not provide adequate on demand performance. Specifically we have come across some very small 1/40 HP (20 watt) pumps that only provide 3 - 5 GPM flow and they really don't work well in an on demand environment. A simple test you can perform would be to unplug the pump at night before you go to bed. Then, first thing in the morning before anyone uses hot water, get a timer with a second hand and plug the pump in. Hold the return line and time how long it takes for the pipe to start getting warm. Anything longer than 60 - 90 seconds will probably not provide adequate performance.
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.