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 138390 times
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Waiting for cold water reminded me of our system. In the winter we wait for the water to run hot, and in the summer for the water to run cool. Often in the summer I can take an entire shower using "cold" water alone. This is why we have a milk jug at the sink to capture some of the water that is wasted in the waiting.

Posted by SursumCorda on August 19, 2008, 2:21 pm

I know the feeling, we too ended up taking back our Grundfos system which is just like the watts premier you spoke of. We were suspicious after reading the instructions over. The instructions said something about testing to make sure the comfort valves are working properly you should shut off the cold water supply and open the cold water faucet. If water comes out the cold water faucet then the valve is working properly. After reading it a few times I finally understood the process. The black by-pass valves that install under the sinks allow water from the hot side to passover into the cold side until hot water closes the valve. My problem with the Grundfos UP15 and the Watts Premier is the by-pass comfort valves they use. When installed there was just no way to get "only" water from my cold faucets. Even with the system off, using our cold water faucet pulled water out of the hot water lines and cold water lines. The thought of my water heater waking up whenever I used my cold water was too much for me to accept. The only one that worked for us was Readytemp by Temtrol. A bit pricey but nowhere near the cost of installing a tankless, so we kept it.

Posted by Silvermagnum on August 22, 2008, 4:27 am

The system should work such that it doesn't pull hot water from the hot water side unless the temperature is low on the hot side, in which case, it would run whether or not you had the cold water running.

I talked to a guy at Home Depot, who said his solution was to run a third line from the hot water side at your sink and plug it into the drain on the hot water tank. No pump required. He said he had done it a couple times, and it "just worked", something about feeding by gravity. I was skeptical, so he said look it up on the internet.

For us, I was replacing the pipes anyway, to get rid of the clogged up pipes (mostly iron) and ran the hot water line in a shorter direction, so the water gets hotter quicker than it used to - we'll have to see if that is enough.

Posted by jondaley on August 22, 2008, 1:04 pm

---"So, now you waste warm water and time as you wait for the cold water to cool down."---

I wondered about that. But as I understand it, the systems that work properly do not allow a backflow from the hot water line, when using cold water. And while the water sitting in the cold water line might not initially be as cold as before, it would seem that would only be an issue if one needs water colder than "luke-warm" - which I never do. Setting the recirculator hot water temperature setting too high, would mean hotter water (than luke-warm) in the return line (cold water line) but that's manageable. No need to have it at maximum - at least not for me. So warm water returning through the cold water pipes shouldn't ever be really hot. And I can live quite comfortably with a cold water line that initially delivers luke-warm water and a hot water line to my shower that initially delivers skin comfortable hot water - although not steaming hot water.

Posted by Bill on January 3, 2012, 11:44 am

You have a point, but the issue is that whatever temperature you set it at, both the cold and hot water pipes will have the same temperature in them. It might be the case that you could set the temperature at a low enough temperature that it is tolerable for either cold or hot, but I'm not sure.

As far as backflow, the issue isn't that the warm water from the hot water pipe goes into cold water pipe *while* you are using it, but rather the entire design is that when you aren't using the water, the hot water gets too cold, and it sends it back down to the hot water tank via the cold water pipe. (though it seems that the recirculator could turn on while you are using the cold water and direct warm water directly to the cold pipe until the water warms up enough and it then shuts off, in which case it would take twice as long as normal for the cold water to get cold - but maybe they watch pressures at the inlets or outlets to decide if you are using the water or not, and prevent that issue. The first issue is not preventable in a two pipe design).

If I ever pipe in a system from scratch, I might do the three pipe system, or think about an electric instantaneous heater, though I was just looking at them again this morning, and the power requirements are so high in order to get a reasonable amount of degree of rise, so I'm not sure if they really work anywhere I've ever lived.

Posted by jondaley on February 12, 2012, 10:19 am

The instantaneous electric hot water heaters are not worth your time. The amount of electricity that they require to heat the water is absolutely amazing. I've also found that the electronic components in them don't hold very well.

Posted by Barry B. on March 9, 2012, 12:08 am

Say what you will about the Watts Premier product, but I like it. I use it in timer mode for the peak times. I find it to be an excellent product and met my needs. hot water now, vs waiting up to 30-50 seconds on hot water.

Posted by bob on May 21, 2012, 1:00 pm

My issue isn't that it doesn't provide hot water. It is that you now have to wait for the cold water to cool down.

The fire hall in my township just got a gas instantaneous heater, and I've been waiting to see if the gas bill noticeably changes.

Posted by jondaley on May 25, 2012, 1:07 pm

Wouldnt it be simple to just put it on a switch?? this way just turn the pump on a few minutes before you shower and you would save all that wasted water.?

Posted by derek on September 8, 2012, 7:54 pm

hmm - that's interesting. and i wouldn't think it would take that long, it's probably fast to pump the water up. maybe a motion detector would work - that'd be neat.

Posted by Jon Daley on September 13, 2012, 7:35 am

This system, along with a solar water heater works great!

Posted by John Gonzales on December 28, 2012, 8:39 pm

Yes - I've been wondering how things change with a solar hot water heater.

We will be getting one sometime this year probably, just need to stop pouring money into the sieve, I mean the house.

I was reading somewhere about a solar heating system, and the guy said how great it was to have the windows open in the winter - more fresh air, etc. and since the heat was "free", he could do that.

Posted by jondaley on January 18, 2013, 9:27 am

We're putting one in for a different reason. Our guest bathroom and laundry room are on a long branch that runs thru an unheated crawlspace. When it freezes up and cracks the pipes, it's a mess to fix, lying on your back in the mud. I put in heat tape.... Until it failed without any way of knowing about it!

So now I'm putting in a recirculator to keep both lines warm in the winter. We can always turn it off in warmer weather.

Posted by Kent Michaelsen on January 26, 2013, 10:05 am

I have a simple recirculator that just moves the hot water into the pipes at a certain time in the morning. I have it set so it does it just before I take a shower in the am. It doesn't use any noticable amount of electricity and I no longer have to run the water for five minutes to get to the hot water. I'm quite happy with it.

Posted by Cassie on May 28, 2013, 3:01 pm

How about putting the recirculator on a timer (like a christmas light timer), so it only turns on when everyone takes a shower or bath? Would that work?

Posted by Gonzo on January 25, 2014, 2:00 pm
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