Hot Water Recirculation Pump - Alternative to Point of Use Water Heater

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In my research the only drawback I gather is that there's warm water in your cold water line during those times, but from what I understand that warm water quickly clears when turning on cold water.

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I've seen the same thing. I think having lukewarm water for a few seconds on the cold side verses having to run the cold water out of the hot side for a minute and a half would be worth the trade.

Yes - not that particular unit, but the Watts recirc pump that attaches directly to the top of the tank water heater - works great in getting instantaneous hot water on the other side of the house. But I’m sure you have an electrical outlet under the kitchen sink for the garbage disposal so that unit you are considering would be a logical choice.

As others have mentioned you get a little luke warm water out of the cold water faucet at least initially.

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Since my water heater is in the attic, I can easily add a receptacle on a rafter above it. The only issue with having it in the attic would be accessing the manual setting on the timer when desired. In that case, I could set it on manual and add a smart plug/timer that I can control with my iPhone.

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That would definitely work - good idea using a smart plug - b/c it was/is a pain to reset the timer to the correct time in the attic after power outages.

I considered one of those in my new build. I didn’t and instead put two very large tankless. The wait on the farthest run is not that bad probably 20-30 seconds. I really have no input other than I don’t know if it’s worth the money and time to install this. Also not sure if I want my water heater clicking on and off that much to keep the water heated. I feel like there are only so many ignition in the life of those things.

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I looked at your video and it appears that they are using the cold water piping to circulate hot water. I’m confused as how that works.

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Explained in video above, but here's the text version:

The pump under the sink draws from the hot line and sends it back through the cold. At first it seems like the pump would have a hard time pumping against the cold water pressure, but since both the hot and cold run all the way to the water heater tank, it makes a circuit. At the water heater, when the pump is drawing hot water, normally new cold water would be entering the house from the main. Instead, the cold water is backfeeding from the pump to keep the tank full.

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Any time you open a faucet, use a hose bib, or an ice maker calls for water; you draw more water from the main.

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Correct, because water is escaping the system. But if you don't let the water escape, and instead connect a hot to a cold, you have completed a loop, a circuit, between the two sets of lines through the water heater tank. It's all at the same pressure so a pump in-line can move water either direction without drawing from the main.

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I listened to the Watts tutorial. They use a special fitting. It serves a function and permits hw to enter the cw system. I think it also regulates the amount of hw which permits the hw to flow slightly and at a restricted volume; thus not heating the cw up too much.

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I think the Watts pump goes at the water heater, so the special fitting under a sink serves the purpose of completing the circuit. It's the same principle, just imagine moving the pump along the hot water line until you get to the check valve under the sink, then integrate the check valve into the pump. It doesn't matter where in the circuit the pump is, you just need a circuit.

I think they work well but you'll pay a slight energy penalty for essentially asking your water heater to keep that additional volume (minimal) hot and overcoming the additional heat loss in the recirculated system.

It may only amount to a few dollars a month so I would give it a shot.

The only issue I can see is the convenience you get depends on the HW distribution system.

For instance if the water heater is located on one end of the house and you put the special fitting on the other end of the house at a lavatory that would be better than if the water heater was in the middle of the house.

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Only problem with this is that outlet is on a switch and will only operate when you turn on the switch to run the disposal. There should be an outlet for the dish washer under your sink. As long as it won’t overload the circuit, you should be able to pull power there.

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That’s true - I have two outlets under the sink, one for the DW and the other for the Garbage Disposal.