hot water on long runs

[shaken-n-stirred]

New Construction:

I will have a hot water tank with a run to the first sink in a master bath only 10 or 12 feet away from the tank (including the vertical drop down from the top of the water heater). This run will continue on to a shower at the end for a total run of say 25 feet. Just above the tank is a full bath. Can not do much better than that.

Then I need to get hot water to the other end of the house for a kitchen, laundry, 1/2 bath, and another full bath. The line / lines to all but the 1/2 bath will be about 50 feet, 1/2 bath more like 30+

Obviously, there is going to be cold water in that 50 feet. I don't like the wasted energy of the recirculating technologies. That waste is huge. Are there any other logical, reasonably inexpensive options to help reduce the delay for hot water?

I might be able to get a small 5 gallon, 15 gallon storage heating tank in the crawlspace under the area in question making the run to the fixtures more like 20 feet and run the hot water from the main tank into that tank. Seems a bit stupid to have 15 gallon tank running just to avoid 30 feet of cold water in the line proceeding the small tank.

Would it make sense to put a small instant / tankless heater 30 feet from the main tank and tee off from there to the fixtures in question. I would think I could again run the HOT water from the main tank through this device so that it basically would only need to heat that first 30 feet of water before hot water from the main tank reached it and the unit would then stop heating the water. I don't know if running hot water through the tankless would hurt the unit or not, or if there are other issues with this plan. Thoughts.

Or if I don't want to waste the energy on a recirculator should I just accept the inconvenience and wasted water / wasted energy of leaving hot water in the long run (I understand that is a waste as well, but not as much as trying to keep hot water in that pipe at all times)

Thoughts

 

[havasu]

http://www.homedepot.com/p/Watts-Hot-Water-Recirculating-System-with-Built-In-Timer-500800/100426993

Here is what I just installed. My faucets are now instant hot, and the cost is just a few cents a day for the electricity. I give it a two thumbs up.

 

[shaken-n-stirred]

Explain if you would. You install the pump at the water heater and a sensor at the distant tap? Is the sensor wireless or do you need to drill holes and run wires? Were is the sensor attached (to the braided supply line)?

What have you found to be a convenient time schedule to run the pump (breakfast / dinner ??)

How do you know it only costs pennys a day? Obviously the cost to run the pump is very very little, but you still lose heat energy from the water in the pipe. Pretty are to measure or calculate? Then again for some people $5 a month is too much to spend and for others $20 a month (still pennys a day) is well worth it.

Thanks

 

[havasu]

There is a thermostat in the black attachment which gets mounted at the far away sink. There are no wires except for the 120v plug that the pump plugs into. It will allow hot water to be pushed into the cold water pipe, but only until it hits 98 degrees. It use to take nearly 5 minutes for my back shower to get hot enough to step inside, and now that time has been dropped to about 7 seconds. Living in California, the price for water is more than electricity and gas combined, and the local municipalities are not on my back for increased water usage.

It took about a week to fine tune the timer to suit our personal needs. I have it turn on in the early morning for showers, again will turn on about dinner time for doing dishes, and then turn on at bed time for face washing, etc.

You secure the pump to the hot water pipe (exit) on the water heater, plug it in, then attach the cold water and hot water supply lines at the far away sink into the black attachment, then use their stainless fittings from the black attachment into your hot and cold water feeds at the sink.

Easy peasy, about 10 minute total time installation.

 

[shaken-n-stirred]

You say the pump runs until the temperature reaches 98 degree? Where is the temperature sensor? If the sensor is in the pump then it would seem to me the temperature would rise to 98 degrees almost immediately after the pump starts up, because it would immediately pump hot water into the pump/sensor. It would seem to me you need a sensor AT THE SINK which would then tell the pump to stop?

Am I missing something?

 

[havasu]

As said in the first sentence above, there is a thermostat in the black attachment, and not the pump. Actually it is more of a rheostat, and when it reaches the temp, the pump shuts down by way of pressure, and no wires connect the pump to the gizmo under the sink.

 

[phishfood]

If it is new construction, I would run a dedicated recirculation line, with a aquastat controlled recirculation pump at the water heater. Add in a motion sensor in the farthest bathroom/s, so that the pump only runs when someone is in the bathroom/s. No wasted water, and very little wasted energy.

 

[havasu]

I agree. That is the best way but surely would cost more than $200, which is how much my unit costs. There still is no water waste with my system. The only downfall is the cold water tap is lukewarm for the first 10 seconds or so, which is still fine 90% of the time with me.

 

[shaken-n-stirred]

Thanks havasu. A rheostat makes sense, but does seem like it is a receipt for failure and or a bit of constant leakage past it.

 

[shaken-n-stirred]

Hey phishfood, what is an aquastat control?

As for a motion sensor, not sure that is a good solution for me. One bath on the run would only be used by stay-over guests, the laundry ... well not a logical place for a motion sensor, the 1/2 would not be used very often by my wife and I, then the kitchen ... I fear the kitchen would have lots of motion and much of it not water related. Thanks for the thoughts. Please answer first question about the control

 

[frodo]

if it were just one room, i would say wire the pump to the light switch.
common since, turn on the light you have hot water.but you are wanting the system at 4 rooms

it can still be done using the light switch's, it will take a electrician knowledgeable in low voltage work.

we refer to them as "control guys" or "out of control guys"

he will run a wire back to the pump from each room, then using relay or a mouse tied to a string
wire a box next to the pump to tell it what to do.

wired to the light is the only way is see to circ the line "on demand"



aquastat sensor is strapped to the side of the pipe sensing temp. tells a switch to open or close

 

[phishfood]

An aquastat is installed on the return piping of a recirculating system just before it is fed back into the cold side of the water heater. It is set to close the circuit and supply power to the pump at a set temperature, say for example 105 degrees, and then will open the circuit (cutting power to the pump) at another set temperature, say for example 120 degrees.

That way, the pump will only run once the hot water system starts to cool down. Combine that with motion sensors or push button controls, and you have a system that gets you hot water when you need it, without wasting a bunch of energy when you don't need it. You could also supply the pump with power through a timer outlet, if your family has predictable water usage patterns.