I have read that a family of four can waste 16,000 gallons of water a
year letting the water run waiting on the water to get hot. I am
considering installing a Hot Water Recirculation system in my home. My
house is a single story home about 1700 sq ft. I saw on the internet
about making a manual loop back system where I run piping from the
furthest faucet to the discharge spickit on the water heater. Then you
are supposed to insulate the hotwater pipes except for the last ten
feet of pipe going to the discharge spicket. The theory is that the
hot water will expand and automatically force the colder water near
the discharge spicket back into the water heater to be reheated.
Suposedly the water will keep circulating by convention.
I am also considering buying a pump to place on the water heater along
with a special valve that goes on the furthest sink from the Hot Water
Tank. The pump forces the hotwater through the system, and the colder
water at the furthest point gets forced back into the cold water line.
This system uses electricity.
The pump type system cost 200 dollars, but doesnt need any return
lines installed. It also cost money to run the pump. If you have any
first hand knowledge of either of these systems, I would appreciate
any advice. Which type system would you recommend? Is it worth the
money? Thanks for any advice.
no...you cant insulate the whole loop if you are going the manual
route. if the loop is the same temperature, there is no movement in
the loop. By having the last ten feet with no insulation, it cools
more thus causing the water to circulate rather than stay stationary.
The following I pulled off the Ask the Builder Web Site...
When water is heated, it simply gets lighter. It wants to float to the
top of cooler water. Cool water wants to fall. If you have a loop that
projects upwards, the cool water wants to fall down the loop while the
hot water goes up. Gravity fuels the motion.
It works in this fashion in your house. You already have half of the
loop in place. This is your hot water piping distribution system which
begins at your hot water heater and ends at the farthest fixture which
requires hot water. If you were to install copper piping leading back
from the farthest point and from other high points in the existing
system, you would have a loop. This return loop connects into the
bottom of the hot water heater where the current drain valve is
located. It is that simple.
The flow of water through the loop is very slow. However, that doesn't
matter. The only thing that is important is that hot water is near
each fixture. Without a loop there is no movement, so any movement is
better than none!
Those of you who live in a house on a slab or where a majority of the
hot water lines drop below the heater need to use a recirculating
water pump. These are simple devices that connect in line in the loop.
They are often located near the water heater, however, they can be
anywhere in the loop. The pumps circulate water at low pressure and
low speeds. Once again, there is no need to have lots of water moving
through the loop. It is just important that the water is hot near the
If you install one of these pumps, remember that you need to install
unions on either side of the pump. Unions are special fittings that
allow you to break into the piping system and reconnect without
soldering. Water meters are always installed using unions. Look at
yours and you will see what I mean.
Once you decide to install a recirculating loop, you need to be
concerned with energy loss. The loop will work fantastically without
insulation. In fact, it works best without it! But, this can also
cause your water heater to cycle on and off more often. Remember, you
are bleeding heat from the heater when the loop contains hot water.
There are numerous ways to insulate the pipe. Many insulating
materials are made exclusively for water piping. They fit snugly over
different sizes of pipe. Some insulation, like the foam types, must be
installed as you install the pipe, not after the loop is constructed.
When you select your insulation material, ask how and when it should
Piping installation methods must also be altered. Some people attach
water piping to the sides of floor joists. You can't do this with an
insulated loop system. The pipe must stand away from floor joists so
that the insulation is not crushed. Special inexpensive pipe hangers
allow you to do this easily.
All of the hot water lines that lead from the heater must be
insulated. They need to be insulated up to where the return loop lines
connect and slightly beyond. The return loop also needs to be
partially insulated. If you insulate the entire system too well, it
may not work! Remember, the water has to cool at some point for the
loop to start its gentle movement. I suggest that you leave the final
15 feet of return loop uninsulated.
Beginning the Loop
Houses that do not have a recirculating loop system have hot water
pipes that branch off a main line and stretch to each fixture. The
ideal loop system would have you start the return loop as close as
possible (within 2 feet) to each fixture. The closer the return loop
starting point the closer hot water will be to the fixture.
Your existing home can benefit without getting this close to a
fixture. As long as you can cut the distance in half or more, you will
see a much more rapid hot water access time.
The return loop begins with a simple tee fitting as close to a fixture
as you can get. The tee simply creates a right or left turn leading
the way back to the water heater.
On your way back to the water heater you simply create other
connections as other return loops join the pipe on the way back to the
Air Locks - BIG PROBLEMS!!
As you construct your loop system, you must be concerned with air
traps. What are these? Well, you know the drain traps under your
sinks? Imagine if you did this upside down with a water line in a loop
system? You would capture air in this trap since air is lighter than
Air can get into a plumbing system in any number of ways: a water main
break, a repair process in your own home, dissolved air within water,
etc. If you create a trap, the air will collect in the trap and BLOCK
movement of water within the return loop. Air is not a problem in the
regular water piping system. The rapid movement of water through the
pipes when you turn a faucet on pushes the air out of the way.
Remember, water moves sloooowly through a gravity loop.
Just before the loop enters the bottom of the hot water heater you
might need to install a simple check valve. These are one way valves.
This valve will prohibit in-rushing cold water from the bottom of the
hot water heater from flowing backwards through the loop when you open
a hot water faucet somewhere within the system.
Check valves are not always necessary. Some systems need them because
of friction loss and other obstructions that make it easier for the
hot water to flow backwards through the loop rather than the correct
direction - from the top of the heater!
These valves can be installed after the loop is completed. Install it
in the vertical loop pipe just before it enters the hot water heater.
You might want to try installing the loop first without one and see
what happens. If you begin to get cold water at a faucet when you
should get hot, you know you need a check valve.
As the loop returns to the water heater it connects at the low point
of the heater. This is always the location of the heater drain valve.
This valve is simply screwed into the heater. Attach a wrench to the
valve and turn counterclockwise. It will come out.
Install an insulated nipple in place of the valve. This will minimize
corrosion possibilities. Then as soon as possible install a tee
fitting with female threads at the tee. If you use the right one, the
drain valve will screw right back into the tee. The other end of the
fitting allows you to connect the loop to the heater.
Shut Off Valves
While on the subject of valves, let's talk about the shut off valves
on top of hot water heaters. I have seen some aggressive homeowners
install a shut off valve on both the hot and cold water line. They
thought this would help in the event they need to switch out the
heater. Well it does help. It also creates a potential BOMB.
If some idiot turns off both valves (happens everyday somewhere), and
the pressure relief valve malfunctions or was never installed, and the
heater thermostat malfunctions, the heater will explode. It has
happened more than once.
Only install a valve on the COLD water line, never on the hot line.
With a pump system you could install a timer on the pump to turn it off
when you are not likely to need hot water. I have toyed with the idea of
putting a pump system in my house and putting a momentary push button
switch at the bathroom vanity hooked to a timer/relay which would turn
the pump on long enough to get HW to the faucet. Larry
This leg of the discussion is about
"I have toyed with the idea of putting a pump system in my house and putting a
momentary push button switch at the bathroom vanity hooked to a timer/relay
which would turn the pump on long enough to get HW to the faucet."
That is what you responded to.
No sir, I responded to the sentence JUST BEFORE what you are
quoting... "With a pump system you could install a TIMER on the pump
to turn it off when you are not likely to need hot water. I have toyed
with the idea of putting a pump system in my house and putting a
momentary push button switch at the bathroom vanity hooked to a timer/
relay which would turn
the pump on long enough to get HW to the faucet".
I doubt that 16,000 galons is correct.
And I doubt that there will be a resonable payback of your
investment. I think the only reson to consider these systems is for
your conveinence so you don't have to wait for the hot water.
So do the install if you don't want to wait for hot water but I doubt
it will save you any money.
I bought one on EBay that is a Laing autocirc 2. It works pretty good. Paid
a lot less than $200 for it. Water at the farthest tap from the water heater
is always hot when I need it to be. Before I would wait about a minute for
the hot water to show up. There is a timer that you set to run the small
pump that can be set in half hour increments for the entire day so that it
is not running when you don't need the hot water. The valve that is under
the sink only opens up when the water temp goes below the set point, thus
allowing the water to circulate back to the water heater and push warm water
to the valve. When the them reaches the set point, it closes. The only thing
that I do not like about it is that the cold water is now warm and you run
into the same problem if you want cold. This is not really a big problem as
I usually keep a jug of water in the fridge to drink and any other use of
water, warm is not a problem. I had a problem with the pump making a little
banging noise, called Laing, and they sent me a new impeller that was
redesigned in a few days.
I like it, not so much for the money savings, but for the not having to wait
The pump has been discussed pretty thoroughly here...
I have a Laing Autocirc and it has been nothing but reliable and has
paid for itself many times over.
Do the math. For your size of house I would suspect that the longest
run is less than 50' so each draw through will be less than 1 gallon.
To waste 16,000 galons a year you would need to do over 40 draw
throughs per day! You likely aren't doing anywhere near this amount.
On Sep 6, 10:45 am, email@example.com wrote:
Seems like a complicated answer/solution to a minor problem?
For the added convenience of hot water within a few seconds of turning
on the tap?
Add the financial and ecological costs of manufacturing, buying,
installing and maintaining another pump; and it's running costs; is it
worth while? Also, while probably highly reliable it's something else
to go wrong?
In our house the longest run from the electric hot water tank is about
40 feet of half inch copper pipe. That's about 120 cubic inches of
hot water in the pipe that will cool down from around 140-150 F to
house temperature; releasing it's heat within the house envelope. Same
as we leave warm shower/bath water in the tub to release its heat into
Since at least 9 of the 12 months here require some electric heating
the so-called 'lost heat' is not only very minor but it offsets
electric heating! Considering the amount of water (if actually
wasted?); it is much less than one flush of even a low water usage
I think any reasonable analysis quickly concludes that energy isn't
the main issue. It's the convenience of having hot water quickly
when you want it. And anyone who's had a large house with a long run
for the hot water knows it can take awhile to get hot water. I see
nothing wrong with installing one of the pump systems with a timer and
temp control. You could also use a motion sensor to get the water
going as soon as someone enters the area, which I think would likely
be an optimum solution.
My previous house took over 90 seconds to get full temp hot mater to the master
bath. Yes, it was a stupid plumbing plan. Even worse was that the master shower
and master vanity were independent runs.
My new house has a timer based recirculator for morning showers. It's fantastic.
"Tell me what I should do, Annie."
"Stay. Here. Forever." - Life On Mars
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