#PEX SIZES GPM INSTALL#

So… w here do the pinhole leaks come from?Īs soon as you put a pump on pipe, the pump creates velocity, which is what it is supposed to do. This is one way to add instant hot water to an existing plumbing system that does not have a recirculation system.

Slick, huh? There are no pinholes, because there is no recirculation line. For high-traffic areas, like a kitchen, this can also be accomplished with a button near the sink so the pump is only activated when hot water is actually needed A thermistor on the pump signals when the water is hot enough to shut off the pump. When an occupant walks into a room, a motion sensor detects movement and activates a small pump under the sink that draws the hot water up to the faucet and pushes the cooler water into the cold water line for about five seconds.

#PEX SIZES GPM INSTALL#

Don’t use a spring check valve, because there is not enough pressure to open up the spring and allow recirculation.Ī third solution is to install an under-sink recirculation pump, as shown in Figure 5. Another key to gravity recirculation is the swing check valve mounted horizontally on the return line. For example, the plumbing system in Figure 1 won’t work because of the fixtures below the recirculation line. Also, gravity recirculation doesn’t work with every plumbing system. The key to gravity recirculation is to make sure the pipes are well insulated, except for the last 15 feet. I have never heard of a gravity recirculation line with a velocity pinhole leak. The great benefit of this method is that there is no need for a pump, which means no velocity issues with the pipe. This uses the physics that cooler water is heavier than hotter water and will sink back down to the water heater to be reheated, thus creating water flow. In residential applications, another solution is gravity recirculation, or thermosiphoning.

The water is circulated by a small recirculation pump. One method that has been in use for decades is a recirculation line running from the farthest fixture back to the water heater (see Figure 3). Later, when the farthest faucet opens, it takes quite a long time for hot water to get to the fixture.įigure 2: New-construction home plumbing example The problem is, when there is no call for hot water, the water cools off in the lines. The “time to hot water” might be more than a minute or even longer (see Figure 2). Today’s new-construction homes can have up to three or four baths on different floors and on different ends of the house with plumbing runs of 70 feet or longer. Thus, there was a very short distance to the faucet, and as a result, a very short “time to hot water.”įigure 1: Plumbing for houses built in the 1950s and 1960s It usually had one bathroom and was piped so all the plumbing fixtures were stacked right above the water heater. Figure 1 shows the plumbing system for a typical house at that time. That way, when an occupant opens a faucet, there is hot water available nearly instantly.īack in the 1950s and 1960s, we didn’t really need recirculation, at least for residential, because of the way houses were piped. To reduce this waste, we can use a recirculation system, which circulates hot water through the pipes. Waiting for hot water sends millions of gallons of water down the drain each year in large commercial buildings. If this is how much water is being wasted by a family of four, imagine how much is being wasted in a 200-unit, multi-housing project.

Department of Energy, an average family of four wastes up to 12,000 gallons of water each year waiting for hot water. This is water that would otherwise go down the drain as a user waits for hot water to travel from the water heater to the fixture. Beyond eliminating an inconvenient wait for hot water, a recirculation system saves thousands of gallons of water annually. This is both a waste of water and a waste of energy, as partially heated water is sent through the line and goes down the drain.Ī recirculation system is designed to make hot water available at the fixture nearly instantly. All of us know what it’s like to turn on a hot-water faucet and wait… and wait and wait for the water to get hot.

Pex sizes gpm