hot water recirculation pump

I am looking at a hot water recirculation pump for my house. Since my hot water is not set up in a loop back to the tank, I would be using what I see called a "temperature sensing bypass valve" at the far end of the run. It looks to me like this valve simply connects the hot water line to the cold water line when the temperature is low which allows the pump to circulate water.

My question is about using this type of setup. Is seems to me that you would end up with the cold water line always warm or hot when you first turned it on since you would be pushing hot water through the valve into the cold line. Is this true? Do people have good results with this type of recirculation setup? Is there a better way to go short of installing a return to the tank at the far end of the run?

Thanks

We have this system. Watts/Grundfos with the thingies under the sink. (We have two of them because the lines from the hot water heater go in different directions.) We are very happy with it. It works well. Instead of waiting up to a minute for hot water when it's cold out, it's nice and hot in 3-5 seconds.

The amount of water that rolls over into the cold line is the equivalent of a drip/dribble -- just enough to keep the water hot-ish on the hot side. This mixes with the cold in the line closest to the sink at the far end of the line. It's not enough to make the cold water at the sink anything but pretty warm. Run out a glass-worth of this warm water when you turn on the cold, and you're back to cold. At the sinks or fixtures further back down the line, it's not even noticeable. We had a guest today staying in the room where the thingy is; the person noticed the warm water on the cold and asked for ice water. We just told her to run it a second and it would get cold, and it did...

You seldom turn the cold water on and use it immediately , so the "tempered" water that comes out initially would be "wasted" anyway. When the cold water is HOT, then you know it is time to replace the mixing valve.

Any noticeable increase in your utility bill for heating the water? Of course I may save more on my water bill than I would pay for any increase for heating the water ,,,

az10sbum said:

Any noticeable increase in your utility bill for heating the water? Of course I may save more on my water bill than I would pay for any increase for heating the water ,,,

Click to expand...

I haven't seen any amazing differences in our oil bill, but there are so many factors in that bill that I'm probably not a great example. However, it makes sense that you would use a little more fuel.

I'm pretty sure that water is so much cheaper than fuel that you would have to save an enormous amount of water to offset even a small increase in fuel usage. It's true that you would save gallons of water every day, particularly if you have a system that would require you to run the water for 30 seconds to a minute to get your hot water. Our plumber actually was surprised at how significant the difference was; he thought that 15-20 seconds was our wait, and it was really four times that. I timed it out, and we were running it 30 seconds to see some warm then another 30 for it to get it close to hot. And this after reinsulating our hot water pipes. Now, it's not instant, but it starts at warm instead of cold, 3-5 seconds and you have good hot-ish water and the hot-hot not long after that...

I have mine on a timer so that it does not run when I'm normally asleep. If I'm up really late or early, the difference in time it takes to get hot is dramatic. This does save a little bit, but I do it as much for wear as I do for economy. You can set it up 'on demand' so that the pump only runs when you command it. But, you have to wait for it to deliver the hot, the difference is you're not dumping it down the drain. For me, that was not worth the setup and slight savings.

If you can add a return line (and you may only need one from the furthest point), that is the best of both worlds, but in many cases, that's difficult. How complex a return line(s) setup is depends on how your fixture are strung out in the house...in mine, one cross-over was sufficient to affect all fixtures.