DRAFT GreenPoint Rated Existing Home Rating Manual version 6.0 | Page 58

G

Plumbing The goal is to place the recirculation pump or the sensor on each trunk line at the fixture furthest from the water heater in order to reduce the hot water wait time to less than 15 seconds at each commonly used fixture in the home. This may result in the need for more than one on-demand circulation pump. The layout of plumbing lines and the hot water pathway may be assessed visually if pipes are exposed. Alternately, the following test can be completed by the homeowner to determine the furthest fixture on the trunk line and therefore, the optimal location of the on demand pump(s) and their associated demand controls: ? Complete a timed test for each sink. First thing in the morning, draw the hot water on full hot at one sink in the house and measure the time it takes for hot water to arrive at the fixture. Write down the time. Optionally, measure the time (and volume, as described below) for showers. Note that this procedure assumes that flow rates at the measured fixtures are similar (+/10%). However, if flow rates are not similar, then the time required for hot water to arrive at the fixture cannot be used by itself. Instead, it is necessary to multiple the time by the fixture’s flow rate (in gallons per minute) to calculate the volume of water. To measure the flow rate, turn the tap on full and capture the water for a specified period of time. Choose an easy multiple of 60 seconds (5, 6, 10, 12, 15, 20, or 30 seconds); a longer time will give a more accurate result, but the volume or weight of the water captured may become an issue. 10, 12, or 15 seconds are the times most often used. Divide 60 by the chosen time to determine the multiplier. After capturing the water, measure its volume and convert the result to gallons. Multiply the result by the multiplier calculated earlier to determine the flow rate in gallons per minute. Multiply the flow rate by the length of time required for hot water to arrive at a fixture to determine the volume of water used at the fixture. Municipal water districts may have water flow measurement bags for verifying flow rates. ? ? ? ? Complete the same test on successive mornings for the remaining sinks (and, optionally, showers). Be sure to perform the test for every fixture on a separate day. After completing the timed tests on all desired fixtures, go to the sink with the longest delivery time (or largest delivery volume), turn the hot water on full, and measure the time (or volume) until hot water arrives. Immediately after hot water arrives at this location, go to each previously measured sink, turn the hot water on full, and measure the time (or volume) until hot water arrives. Also perform this test for all showers, ev en if they were not included in previous steps. Compare the measured time (or volume) from the first morning to the last morning. If there is a decrease of 50% or more from the first to the last morning, then the fixture is on the same trunk line as the furthest sink. The higher the percentage reduction, the closer the fixture is to the trunk line.

Installing an on-demand pumping system makes sense if the wait and waste is large in a hot water that is regularly used (for example in the kitchen or master bathroom). An additional benefit may be obtained if two or more hot water locations are on the same trunk line with the furthest hot water location. If there are two or more often-used hot water locations with similar wait times (indicating the fixtures may be on separate trunks), it would be effective to install an on-demand pumping system in each location. VERIFICATION Measure G1.1 Field Verification: The Rater must complete field verification and take representative photos of all hot water pipes in the home. Measure G1.2 Field Verification: The Rater must complete the following test: GreenPoint Rated Existing Home Rating Manual Version 6.0, September 2013 © Build It Green

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