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I am interested in getting a hot water recirculation pump installed so that I can get hot water faster to each of my faucets.

From looking at the picture and researching I believe I have PEX in a "home run" configuration:

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When doing my walk through with my warranty guy I mentioned I was interested in getting a recirculation pump, but he told me he wasn't sure how that works with a manifold and that I should investigate first.

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up vote 2 down vote accepted

I'm aware of two types of recirculation pumps.

The traditional system runs a connection from the most distant hot water tap (often the kitchen or master bath) back to the hot water heater. From there, you would have a check valve and a pump that moves the hot water from the tank, to that distant fixture, back through the return line that was added, and into the hot water tank via the cold inlet. With a home run PEX system, you don't have a most distant fixture.

A second type avoids the need to run the return line to the hot water tank by connecting the distant fixture by using the cold water line for the return. This means your cold line would end up being filled with water that had gone through the hot water tank, which is a significant drawback to this system (you really don't want to drink the water that's been through a hot water tank with all the sediment).

Since PEX is typically a home run install, this means you'll need to install a device on each fixture you want to have recirculated. If, for example, you only hook up the bath tub, you won't see any benefit at the sink if they are each a separate home run. Each of these connections would be independently controlled, either with a thermostat, timer, or some other on demand switch, so that your cold water lines don't fill with hot water. You will also need to have a power source at each fixture to run the pump.

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On a side point just out of interest as I'm a plumber apart from the individual flow control what is the advantage of this home run manifold over the traditional main run with tees off it? (which would use heaps less materials) –  UNECS Sep 20 '12 at 2:38
@UNECS It seems a bit odd to me as well, but then I'm used to working with copper. With PEX, much of the cost is in the connections, so it might be cheaper. You also avoid the pressure changes from someone flushing a toilet. With any issues or repairs, you can shutoff the line running to a single fixture. And hopefully there are fewer issues since there aren't any joints hidden inside of the walls that could fail. –  BMitch Sep 20 '12 at 11:38
Yes, the biggest advantage to a PEX home run is in the combined material and labour savings. All you need to do is layout where the fixtures are going to be installed and where the header is to be located and then no more measuring is required. Just drill holes and pull the PEX. –  pdd Dec 27 '12 at 17:20
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