Current Plumbing schematic HW only

I'm going to re-plumb my house. It's a 3 bed, 2 bath house. All the plumbing is on the main level, and the basement is partially finished. I'm renovating down in the basement and decided while I was doing drywall work, I might as well cut in to the ceiling and replace the polybutylene pipes with PEX. I got 2 quotes from plumbers and decided I'd be better off to do it myself. I'm very handy and work at a building supply store so I can get a great price on materials. I'm also planning on adding a second shower head in the Master bath when I renovate the bathroom next year.

I was wanting to look at adding in a recirc pump for the hot water. Since I am in the space between the floors, I would do a dedicated hot water return. The hot water heater is in the basement. Let's say the 2 shower heads are approx 10 ft above the tank (if that matters). I'm on a well with a pressure tank and a 40/60 pressure switch.

My questions are this: With my current layout, should I plumb the return line as 2 different zones? What parts am I going to need to do this right (including pump size recommendations).

  • 1
    I don't understand. In these setups, you are circulating hot water in a loop, on the off chance the user wants hot water. How does the (unused) hot water get back to the water heater? Is it a fully plumbed loop? Commented Jan 20, 2018 at 21:35
  • 1
    @Harper yes it is a full plumbed loop. The recirculating line runs from the end of each hot line back to the cold input on the hot water tank with a check valve in the line to prevent cold water flow in the opposite direction.
    – ArchonOSX
    Commented Jan 21, 2018 at 0:53
  • No. This is the current set up. There is no recirculation loop yet. I'm looking for advice how the best way to plumb the loop back. The current configuration lends itself to making 2 zones, but I don't know if that's the best way to do it.
    – A Lewis
    Commented Jan 21, 2018 at 0:54
  • Yes, I think Harper was asking about the proposed setup.
    – ArchonOSX
    Commented Jan 21, 2018 at 0:59
  • 1
    I don't want to push the hot water through the cold lines. I am going to plumb in completely new hot water return.
    – A Lewis
    Commented Jan 21, 2018 at 1:09

3 Answers 3


Here is what I did in my house. I have a ranch style house with bathrooms at both ends of the house. I cut the copper tubing, as close as convenient to the end of each run, and added a tee, a ball valve and a check valve and ran a 1/2" copper return line back towards the water heater. Near the hot water heater, I added a 3/4"X1/2"X1/2" tee to connect the 2 lines together and continued the 3/4" line back to the tank. I removed the drain valve from the bottom of the water heater and added brass nipples and a brass tee, connected the return line and reinstalled the drain valve. In the 3/4" return line I installed the smallest circulating Bronze pump I could buy (B&G model NBF-8S/LW 103257LF .38 amps 39 watts) I wired the pump with a short electric cord with a molded plug. I plug the pump cord into a small "plug-in" timer that I can set to run as needed. You can turn the pump on/off during the day just to keep hot water present near the faucets or just leave the pump on all day and off at night. Remember the pump must be stainless steel or bronze to resist corrosion from the domestic water. My pump has run for 20 years and counting. My longest wait for hot water is 4-5 seconds.


Run a single 1/2" line back from the end of each hot water branch until it gets back to the middle.

Join the two 1/2" lines to a single 3/4" line back to your cold water input to the water heater.

Install a circulating pump with a built in check valve in the line to prevent reverse flow.

Put the pump on a timer, motion detector or both to suit your families needs.

Never have to wait for hot water again.


With that layout, yes, 2 returns seem likely to be advisable. Each return should have a check valve. Debatable whether two pumps would also be needed (would certainly simplify being SURE each loop got circulated, but costs more.) Alternatively, since you are re-plumbing, re-plumb as a single loop.

  • My concern with running it as a single loop is the length of pipe. The hot water heater is in the middle of the house and the bathrooms are on opposite ends of the house. Does it matter, though, since I am creating a loop anyways?
    – A Lewis
    Commented Jan 20, 2018 at 21:43
  • 3
    How about having 2 heaters at opposite ends of the house? I never understood hauling hot water long distances, especially in big long American ranch homes with typically two small clusters of hot water spigots. Commented Jan 21, 2018 at 1:50
  • Using pipe of adequate size and hopefully insulating it to minimize the losses associated with recirculation, the length of the pipe need not be a concern, since you are planning to recirculate. However, Harper's suggestion of two water heaters that might not need any recirculation is worth considering (but might prove cost-prohibitive upon consideration.)
    – Ecnerwal
    Commented Jan 21, 2018 at 16:43
  • My hot water heater is in the middle of the house with bathrooms on either end of the house. Mine works great.
    – d.george
    Commented Jan 23, 2018 at 23:10

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