Our new house has fairly long hot water lines to the kitchen and bathroom, so I was looking for different solutions to getting there to be hot water quicker.  I researched some tankless heaters, and for the kitchen and washing machine (on one trunk) a small heater (12 amps) would have worked well.  But, for the bathroom, a good sized heater (with our 45 degree incoming cold water) would have needed a 200 amp service to the house, with 60 amps (220 volt) dedicated to it.  So, an awful lot of upgrades, not counting the tons of ongoing electricity.So, I bought a hot water recirculator at Home Depot, but it turns out it is junk.  I talked to a sales guy at the manufacturer, and he didn't seem to understand the problem.  The idea is that it watches the temperature of the water in the hot water pipe right under the sink, and whenever it falls under a certain temperature (and also within certain configurable times during the day), it sends the warm water back down to the hot water heater to be reheated.  So, the same water is reheated multiple times, using more energy, but you gain time by not waiting for the hot water to be hot, and also not putting all the cold water down the drain.  I am not sure how much extra energy is used in reheating the water all the time.

But, the way this particular recirculator works is by putting the warm water into the cold water pipe, on its way down to the heater.  So, now you waste warm water and time as you wait for the cold water to cool down.  As far as I can figure out, the time wasted is just about the same, though I could route the cold water pipe a shorter distance, and, you are now putting warm water down the drain instead of cold water.

The sales guy agreed that "potentially" that could happen.  I don't see how it is not guaranteed for it to waste hot water and time.  So, I'll add it to the pile of things to return to home depot - we seem to do that quite often these days.

There are recirculators that use a third pipe, which Watts Premier doesn't sell, presumably why the sales guy had such a hard time admitting their product's weaknesses.  (I am sure it would work quite nicely for heating up the hot water pipe quickly)

Posted by Jon Daley on August 19, 2008, 1:34 pm | Read 129067 times
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Yes, that would be fine and I've wondered about a motion detector, which would be even better. I still don't like the two pipe version where if you want cold water you have to wait for it to cool off, since the normal method of installing this circulator is with just using the existing two pipes (which I get that it is much easier in most cases to not install a third pipe).

If the pumps didn't cost so much I would run a third pipe and then setup the two bathrooms to run on one pipe whenever someone walked into either bathroom, since they are right on top of each other, it wouldn't waste that much water, and save the cost of a pump.

Maybe someday I'll find a cheap pump - I should have saved the pump when I replaced my furnace.

I also have been looking around for a small (110V) electric instant water heater, but I can't find any that have longer than a 12 month warranty, so they must be pretty prone to breaking.

As for Kent's comment above, I'd think that heat tape that only needs to heat the water to a minimal level would be cheaper than using your piping hot water to circulate around and re-heat constantly.

Posted by jondaley on February 1, 2014, 6:27 am

after reading comments on different sites, seems the on demand type units w/b the best. You want hot water push the button and it arrives shortly. still a slight wait, but it works and saves energy.

Posted by Mike on March 5, 2014, 3:05 pm

I've been wondering if we switch to a solar hot water system that then I'll hook up something - there are some faucets that I've stopped using the hot water valve because the water doesn't get hot by the time I'm done with it...

Posted by jondaley on March 23, 2014, 1:53 pm

I purchased the kind that has a black by-pass valve under the sink. I should've done research first. If I knew it would make me wait for cold water I would not have purchased. Why do manufacturers play ignorant and fail to mention that obvious problem. The instructions says that upon hot water arriving at the sink, the valve closes. So, am I to believe when hot water is not at the sink the valve is wide open? After returning it to homedepot we went with ready temp hot water circulator. This system uses a gate valve that opens when the pump starts and closed when hot water reaches the sink. We're using both timer and on demand pushbutton because the kids are on a different schedule.

Posted by Keith on August 17, 2018, 8:47 am
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