I am doing a kitchen remodel and would like to add a hot water recirculator. My plumbing runs through the slab so the kind with a dedicated return line to the hot water heater is not feasible.

I've heard that they have systems that use a pump to bleed the hot water into the cold water line. However, my contractor said he installed one of these and it did not perform as advertised. If that's true I'm wondering how much better it is than nothing.

Has anyone had experience with these kinds of systems? It currently takes a couple of minutes to get hot water at my kitchen tap which is not only annoying but wastes water in a desert area.

TIA...

Steve

Steve -
I've used the Laing Thermotech Autocirc pump for more than 5 years, and I think it is the greatest. Mine is installed in the upstairs master bathroom, which used to take several minutes to get hot water (from the water heater in the basement). Now, I get hot water in seconds. Back then it cost around $250. It is worth it!

The Autocirc is quiet when running, which was a concern of mine. One thing I did have to add later is a water hammer arrester, since I got a thump whenever the pump shut off (when it reached the hot temperature). I used the Sioux Chief unit on both the input and output sides of the pump.

Best of luck,
Wally H.

I am not that familiar with the recirculator but it appears its using power when the water temp drops 24/7. You may want to look into a point of use tankless heater. Rheem, Rinnai and many others all make them. Until 1-1-08 you could get a $300 energy credit on your tax bill but I'm not sure if this will be renewed for 2008. Tankless Water Heater Buying Guide

There is a timer that allows you to specify a range of times when the pump is to work, however, it uses such an insignificant amount of electricity that I leave it running all the time. The pump only runs when the water temp drops below a certain threshold anyway.

FYI,
Wally H.

I was thinking about this one: Hot Water Circulator Recirculator Circulation Pumps
Anybody have any comments?

A bit pricey but sounds like it does the trick. Since these units do not use a piped looped I am still uncertain how they work. Anybody got a laymans explanation?

Having installed a number of them without any issues, I'm with Wally on the Laing pump.

How they work: I can guess.

Suppose you put a check valve (one way hot to cold side) with say a 10 PSI differential. Meaning it will take 10 PSI to open it at the furthest fixture.

If there is no pump or the pump is off, there is no difference compared to regular plumbed.

If you add a pump on the hot pumping toward the cold (check valve) with a bypass, then again the hot water flows normally if the pump is off. Water just flows around the pump.

If you turn on the pump, warm water moves to the cold side until it turns hot.

The trick is in the controls.

If you you it all the time, you'll end up with hot water in the cold and hot sides.

If you run it for just enough time to empty the hot water line of warm water, you have made the cold water slightly warm and the warm water standing in the pipes hot. If you turn off the pump, you can draw water from the cold tap which was slightly warm and it will eventually become cold.

So the trick is figuring out when to stop the pump and when to run it.

The simplest: Push a button every time you use the tap to empty the hot water line.

Next simplest: Anticipate when you will use water and use a timer to run the pump briefly.

So, make it a little more complicated. Use a timer to run the circulator loop when you anticipate water use and use a temperature sensor to stop/start the pump.

So, it just has to move the water until the cold temperature reaches a preset value and run it until it happens or there is excess run time. Like run until 85 F, but shut off in 10 minutes. Cause a recirculate before you anticipate using water or disable recirculate at times.

Does the explanation help?

The Laing Autocirc has a thermostat built in that will automagically start the pump when the water is cold and stop it once enough water has been pumped to bring it up to temperature. No button to push. There IS a timer, but that simply determines when you want the thing to be completely off. I choose to leave it on all the time and just let the thermostat do its thing. You never know when you'll want hot water in the bathroom (where mine is), but in the kitchen, you might be able to specify a timeframe.

HTH,
Wally H.

Hey Wally,

I'm getting that thump every time the pump shuts off and put a water hammer arrester on one side, but it still happens. I see you recommended putting one on both sides. My question is, when you installed the Sioux Chief water hammer arrestors on both sides of your Laing Thermotech autocirc pump, did you install the arresters directly to the wall valves and then run a hose to the pump? Or did you connect the arresters directly to the pump with hoses then returning to the valves?

I hope I'm not too confusing here. So I'm basically wondering which of these you did:

1. Wall valve -> hose -> water hammer arrester -> Laing autocirc

Or

2. Wall valve -> water hammer arrester -> hose -> Laing autocirc

Thanks,
JMG