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I'm looking to install a hot water recirculating pump to minimize the wait for hot water in an upstairs bathroom addition. This bathroom will be at the farthest point in the house from the water heater. I currently have bare walls, so all installation options are open to me.

I've seen some examples of recirc pumps installed directly on the hot water output of the heater, but doing so in my case would require a complete replumb of this portion of my water supply, so I'd like to avoid that.

Can I install the recirculation pump anywhere along the hot water line between the heater and the tap or does it have to be directly over the heater?

Notes:

  • I did see this question, but this specifically involves a thermostatic mixing valve, which I do not have, so I don't believe it's applicable
  • My main concern is the time it takes to get hot water out of the taps, I'm not necessarily concerned about the most energy efficient method of doing so.
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  • Before you install a pump, you should see if it works without a pump. Mine does. My water heater and pump are in the basement. I have a crossover valve at a sink on the ground floor and another one at a sink on the second floor. Even with the pump turned off, the water at the second floor sink (but not the ground floor) is pleasantly warm immediately. The hot water circulates by natural convection, prompted by the difference in altitude. So if feasible, hook up the crossover valve, wait an hour and see if it's warm enough with no pump.
    – MTA
    Feb 8, 2023 at 18:02
  • That's reasonable, @MTA, but I'm currently in the construction phase and want to preemptively install this instead of trying to retrofit after the fact.
    – FreeMan
    Feb 8, 2023 at 18:18
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    As a follow up, it's taking 45-60 seconds to get hot water to the closer of the 2 new bathrooms. The pump is necessary.
    – FreeMan
    Oct 3, 2023 at 14:26
  • Yikes! Is that with or without a crossover valve installed between the hot and cold lines at the point of use?
    – MTA
    Oct 3, 2023 at 14:36
  • I don't have the pump running yet. Need to wire up a new outlet in the basement for it. There's a dedicated return line, so no crossover valve from hot to cold.
    – FreeMan
    Oct 3, 2023 at 14:56

2 Answers 2

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If walls are open and you provide a dedicated return line, rather than using the cold supply line as a return line, you can put the pump (anywhere) in the return line.

A common setup (even for the sub-optimal using cold as a return) is to put the pump at the furthest fixture (where thermostatic control to turn it off when hot gets there is easiest.)

If you want to save some energy you can combine the thermostatic shutoff with a motion sensor (if you want it to work in the dark) or the bathroom lights so it can bring the water up to temperature while you're actually there, rather than keeping it hot all the time. For most bathroom uses that will be nearly as good as hot all the time (won't cover rushing in and immediately trying to wash your hands/jump in the shower, though.) The motion sensor can even be in the hallway the bathroom connects to so it starts sooner (if without need, occasionally.)

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  • I am planning on a dedicated return line (I keep forgetting to provide these helpful details in my questions). Putting it at the bathroom end does make sense, though I think the ones I've been looking at all have 3/4" fittings for installing on the HWH. I am, however, familiar with the "plumbing adapters" section of my local stores, so that shouldn't be an issue.
    – FreeMan
    Feb 8, 2023 at 16:57
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    I really like the motion sensor triggered idea! Thanks for that bonus!
    – FreeMan
    Feb 8, 2023 at 16:58
  • TBH, if it has a remote temperature sensor, though, putting it in the utility area, but not directly attached to the HWH would probably make more sense.
    – FreeMan
    Feb 8, 2023 at 17:02
  • Yeah, that will be quieter, so probably the better way to do it. 1/2" stainless recirculating pump gets results (and will be generally cheaper given the price of bronze these days) - amusingly, the least expensive one I find quickly is from a home brewing supplier ;^)
    – Ecnerwal
    Feb 8, 2023 at 17:04
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If you are planning a loop to feed from the tank, past all the faucets and back to the tank then you can put the pump at any point in the loop.

However, choose the most convenient point considering noise, access etc

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  • Would add close to a power/electrical point/junction box so you can power the pump.
    – crip659
    Feb 8, 2023 at 16:56
  • Walls are open, @crip659, I can add outlets anywhere I want! ;) Point well taken, though.
    – FreeMan
    Feb 8, 2023 at 17:00
  • Also make sure to well-insulate all of the lines (both supply and return) to minimize heat losses over time.
    – Milwrdfan
    Feb 8, 2023 at 22:36

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