Recirculation system
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Recirculation system

Taco recirculation systems  
Install pump at water heater
Install crossover under sink
Choose timed or thermostat operation
Plug into 120V outlet
1 year warranty with receipt
Taco recirculation systems
General Taco manual
General manual
Figure flow rates for recirculation pumps
Basic pump science/ pdf
Grundfos recirculation systems
Grundfos UP series pumps
Install pump at water heater
Illustration shows typical water heater model
Install crossover under sink
Choose timed or thermostat operation
Plug into 120V outlet/ draws 1/4 amp
2 year warranty with receipt
Grundfos recirculation systems at Amazon
Replacement crossover valve
Clip-on thermostat control
Cast iron flange set for flanged pumps
General Grundfos product manual
UP series specification sheet
How to choose proper circulator pump
watts recirculation systems
Install pump at water heater
Install crossover under sink
Choose timed or thermostat operation
Plug into 120V outlet
1 year warranty with receipt
Watts recirculation systems
Replacement crossover valve
Watts sensor valve kit
Watts recirculation system manual
Do not install on tankless
Tankless require .5 GPM
Laing recirculation systems
Laing Thermotech
Install under sink/ buil- in crossover valve
Pump and crossover built into same unit
Choose timed or thermostat operation
Plug into 120V outlet
2 year warranty with receipt
Laing recirculation systems

Autocurc manual
ACT 909 tankless recirculation pump manual
E10 autocirc manual
Laing thermotech

Add air vent to keep air out of line will prolong life of pump
Keeps air out of water line
Smoother flow, less noise

Air Vent

Purpose of air vent: circulation pumps often create bubbles in the water line.
Air bubbles cause noise and cause circulating pump to stop functioning.
Installing air vent at highest point in recirculation loop will vent the air bubbles... pump last longer, and functions as expected.
Buy air vent:
Air vent/ Float vent
Crossover valve
Replacement crossover valve
Watts sensor valve kit
Troubleshoot valve page 3-4
Applies to Taco, Grundfos and Watts. Does not apply to Laing
Crossover valve installs under sink, and allows hot water to circulate from hot side to cold side. Purpose of crossover valve: When recirculation pump is ON, the crossover valve opens and lets hot water circulate back to water heater through the cold water line. When temperature at the crossove valve reaches 95 F, the valve shuts off hot water entering the cold water line. This applies if timer is being used or not. Immediate hot water is available at the faucet. When you turn on cold water at the faucet, the crossover valve closes, allowing cold water to enter the faucet.
Note: Cold is not available immediately at the faucet.
grundfos thermostat
Clip-on thermostat control for UP series
grundfos thermostat
Grundfos UP sereis

Clip on thermostat control

120 volt thermostat-switch clips onto water line
Intended for use with UP series pump and timer
Lets you control pump or any 120 volt circuit based on temperature of water pipe
Read manual and make sure it fits intended application
Local hot tub at YMCA/ temperature set at 105/ Typical shower-bath 110 degrees F
595444 ON at 85 degrees/ OFF at 105 degrees
595656 ON at 105 degrees/ OFF at 115 degrees
Aquastats at Amazon
24 hour programmable timer for UP series pumps
Grundfos recirculation systems at Amazon
UP series pump at Amazon

Clip on thermostat manual
UP series specification sheet
grundfos bushings grundfos super brute
Grundfos UP

Grundfos circulation pump for baseboard heating or water heater recirculation

Requires flange set
Use for whole house... install on 3/4" pipe or 1"

Grundfos UP series super brute at Amazon
Grundfos flange set
Taco flange set
UP10 series with adjustable aquastat (thermostat)

UP 10 series Sell sheet
Re-circulation install/ maintenance tips
Troubleshoot laing recirculation pump
Troubleshoot grundfos recirculation pump

1 horsepower = 756 watts.
Recirculation systems are rated 1/25 Hp  
 1/25 Hp motor = 30.6 watts  
30.6 watts divided by 120 volts = .255 amp
Less than 1 amp
Recirculation system will not overload any circuit

Troubleshoot recirculation system

Electrical requirement/ 1 amp

Hot water recirculation system
Larger image

How water heater recirculation system works 

Part I:  Laing Pump OFF

Hot water re-circulation system with timer turned off

Cold water available immediately, but wait for hot water.

Water- savings estimate of 15,000 gallon per year is promotional foolery: this amount equals 41 gallons per day or 2 full bathtubs of water per day.

Test your home: put empty gallon can under tub spout and see how much water is wasted waiting for hot water. Use water for plants.
Laing recirculation systems
Re-circulation system
Larger image

How water heater recirculation system works

Part  II: Laing Pump ON

Re-circulation system with timer turned on.

Hot water available, but wait for cold water.

Timer saves energy compared with recirculation system that runs full time.
Autocirc uses timer, but also turns off when temperature reaches 95, and turns on when water temperature drops to 85.

Laing recirculation systems
Auto circ at Amazon
Recirculation systems Amazon
Grundfos recirculation at Amazon
Taco recirculation at Amazon

Recirculation in tank
See entire Auto-circ system

Water heater temperature below 140F

Keep Water Heater Temperature Below 140F (60C):

High temperatures cause calcium and magnesium to come out of solution and create solids. These solids can damage pump and reduce water heater efficiency.
Can cause early water heater failure
How to adjust temp of water heater
How to maintain water heater
Temperature needed to kill bacterial 140F

Water temperature inside pipe

When using thermostat operation, the pump turns ON automatically when temperature inside pipe drops below 85 degrees and then turns OFF when water temperature reaches 95 degrees F.
When using Timer, the pump runs for specified amount of time. So if water heater holds very hot water, the full tank temperature will circulate 
Recirculation crossover valve

Recirculation crossover valve

Install crossover valve under sink with Hot on left and Cold on right
If this is reversed, then recirculation system will not work
Crossover valve is one-way check valve... lets water through one direction, and then closes when water tried to go other direction.
If recirculation has stopped bring hot water, but the pump is working, then replace crossover valve.
How it works: "The Comfort Valve is installed at the fixture furthest away from the hot-water tank. Using timer on pump, hot water circulates along the loop through the valve using the cold-water side as a return line. As the temperature rises to 100 F (38 C), the valve closes directing hot water to the tap, thus resulting in a constant availability of hot water.
Replacement crossover valve
Watts sensor valve kit
Example illustrations of installation
Read about crossover valve
Grundfor recirculation system installation

Install pump upright on hot pipe

Install recirculation pump in vertical position on Hot water line.
Which pipe on top of water heater is Hot? 1) Usually the cold line has shut off valve. 2) Top of tank also has H and C markings. 3) Turn on Hot water tap for few moments and use hand to check which pipe feels hot.

Pump installed sideways will not work

Typical plumbing diagrams
Installation manual with photographs
Grundfos circulation timer
Larger image
Grundfos installation manual
General guide for setting timer

Choose: Timer or thermostat operation?

Choose between 'Timed' operation or 'Thermostatic' operation
Use slide switch located on timer dial.

Choose timer and Program specific times: Move slide switch to timer.
Using timer, the recirculation system runs specific times of day
If you use crossover valve installed under sink, then the thermostat will stop the pump when temperature reaches set point.
Function of timer is to ensure that pump does not cycle on-off throughout day.
Timer must be reset after power outage

Or choose Thermostat operation, Move slide switch to ON.
Pump runs whenever temperature inside pipe drops below 85-90 degrees and run until temperature reaches 95-100 degrees. Some pumps have variable thermostats and some have higher setting.

To turn off the system, slide switch to OFF
General guide for setting timer


Timer or thermostat?

Timer can save money if scheduled carefully.
Thermostat operation runs throughout the day. Hot available any time
Cost to operate recirculation pump?
Using the timer and running Autocirc 1 hour a day costs between $11 and $17 per year to operate.
Run autocirc 2 hours a day is $22-34 per year.
Run 12 hours a day costs $11-17 per month, or $132-204 per year.
This includes pump operation and additional time that water heater operates. See calculations

Cost to operate

See larger

Direct return/ probably saves money

Does not use cold water line
Requires dedicated return line connecting to water heater drain port
Saves money since water is not wasted waiting for cold to arrive

Direct return connects to water heater drain port.

How to remove drain valve
Different type of water heater valves
How to flush water heater

Tankless recirculation
Larger image
Best design

Tankless recirculation system

Three Illustrations show:
Top two: direct return line/
Bottom: without direct return line
Direct return line is better installation

Water must circulate through small water heater to ensure there is hot water in the recirculation loop. Reason: small pump cannot activate tankless burner or element

Check valve can be added on direct return hot water line as shown
Add check valve to cold water line for loop without direct return

System can have faucets that are not connected to recirculation loop... add a small 3 gallon under counter water heater to this faucet

Water flow causes pressure.
The small pump creates pressure. The check valve between tankless and recirculation loop (on top illustration) will keep recirculation pump from pushing water into tankless. So the pump is just recirculating hot water in the loop.
Using hot water during a shower also causes pressure... and when tankless is being operated, the other check valve will keep water from being pushed into small tank and backwards through recirculation loop.

It's also true that water flow can cause suction.
For example if end of garden hose is left inside a pond after filling pond.... and you turn on water tap inside house... the pull of water can draw water from the pond if the outdoor spigot has a small seep.
For example if end of garden hose is left inside a pond after filling pond.... and you turn on water tap inside house... the pull of water can draw water from the pond if the outdoor spigot has a small seep.
To prevent this problem, add anti-siphon connection on outdoor spigots.

However, in the case of recirculation pumps, the water flow is not very strong, and the system is a closed loop... a closed loop is not drawing water like an open spigot... and the 1/25 Hp recirculation pump is not moving the water very fast, so drawing cold water into the loop is not an issue.

Compare small water heaters
Water heater valves

Which 20 gallon water heater

For whole house, use water heater with 3/4" pipe fittings
1/2" pipe is too small for household size recirculation system
1/2" is for single faucet
Compare small water heaters

Which recirculation pump?

Each plumbing system is different... distance, diameter of pipe, condition of pipe, number of elbows, ...  effect flow of water.
Compare recirculation pumps

Why isn't there a stronger recirculation pump?

Probably faster pump on small residential pipe would just cause water bubbles, and no water movement, and then resistance would overheat pump?
How to set up Tankless recirculation
Tankless recirculation system
Larger image
Connect Hot from tankless to cold water inlet on small hot water heater
Tankless recirculation system
Larger image
No return line/ not best design
Pump can be located on cold water line
Swing check valve

Swing check valve

Check valve that swings open when water passes one direction.
And swings closed when water tries to pass other direction.
One way valve: Lets water pass one direction, but not other direction

Why is this important?

Recirculation system loop can draw cold water into hot pipe causing cold flashes during shower. This occurs during heavy use periods.
Bad swing check valve can cause crossover, where cold enters hot pipe and hot water never arrives at faucet: Crossover
Swimming pool, or outdoor ponds: If water hose is left in pool or pond or puddle of water, then water use inside home can draw this unsanitary water back through water hose and into home water pipes. Install swing check valve. Do not leave hoses on ground. Or in pool.
Swing check valve at Amazon
sharkbite check valve

under counter water heater

II. Other Hot water option for sink

Point of use water heater

115 Volt, 2-1/2 Gallon point of use heaters available at most home centers
Connect heater to cold water line
Use switch or timer
Point of use water heaters at Amazon
Under-counter water heaters, manuals, and installation
How to increase amount of hot water
Pot heater
Pot heater/ hot water dispenser
Objective: Fill pot for hot water at any sink
12" tall heater heats plugs into 115V outlet
Dispenses 2-3 liters hot water into cup or sink
Use switch or timer
Hot water dispenser / pot heater at Amazon
Sunbeam hot water dispenser
hot water dispenser
Hot Water faucet/ dispenser
Objective: save water, save energy
Point of use hot water

Kohler hot water faucets at Amazon
Franke hot water dispenser at Amazon
Kitchenaid hot water dispenser

III. Other Hot water options for sink

Pot heater or hot water dispenser

Autocirc timer dial

Larger Autocirc image
Auto circ installation manual
Taco 265-3

Taco 265 DIGI timer

DIGI cross reference w/ FM1D
DIGI 240V manual
Taco timer sell sheet

Taco timer at Amazon
Taco recirculation at Amazon


Control pump with cell phone using WeMo

If WeMo or Iris offers a delay option
WeMo programming resources are online
No subscription
WeMo plugs into ordinary 120volt outlet
Control WeMo using phone or tablet
Buy from my associate links
WeMo at Amazon
Belkin WeMo at Amazon
Unlocked cell phone at Amazon

Unlocked smartphone
Unlocked smartphone
How to install recirculation system
Skylink remote control countdown timer
Skylink wireless countdown

Operate recirculation system remotely

Skylink wireless countdown
Skylink estimate 1/3 Hp
Grundfos pump is 1/25 Hp
120V 60 Hz/ 10 watt miminum/ 1500 watt

Operate as ON-OFF or Countdown device/ Up to 500 feet
15 minute - 60 minute countdown

Wireless wall mount transmitter TB-318 at Amazon
Wireless countdown receiver PA-318 at Amazon
Transmitter and receiver
PA-318 manual
How to install recirculation system
Off delay timer for recirculation system
Off delay timer for recirculation system
Push either button to activate delay timer sequence
Another wiring example using push button -or- ST01 programmable timer to start delay

Operate recirculation system remotely from 1-2-3+ different locations

How it works:
Do NOT connect voltage to bell wire going to push buttons
Buy delay timer and base
Connect 120volt Hot and Neutral wires to base as illustrated.
Buy thermostat or bell wire and connect to push buttons as shown
The push buttons receive no voltage or power... do not connect to power source.
Plug timer into base. Choose delay time from .05 seconds to 999 seconds
Push doorbell button. Activates timer.
Timer turns ON and begins countdown.
Pump turns ON and runs until countdown stops. Countdown is off-delay.
When countdown expires, timer turns OFF, pump turns OFF.
Delay timer rated 1/3 Hp.... recirculation pump rated 1/25 Hp

Buy project materials:
Example 50' thermostat bell wire at Amazon
6A855 Solid State timer at Amazon
11-pin plug-in base at Amazon

Push button plate Amazon
Other countdown timers
More off delay and pin timer illustrations
6A855 Manual
AH3-3 wiring

Remote control countdown timer

Operate recirculation system remotely from different location

AH3 off-delay timer
Flip switch and load turns on until delay period expires
120 volt AH3-3 at Amazon

How to wire AH3-3 timer
More countdown timers
remote control countdown timer
Larger image

Remote control countdown timer

120 volt AH3-3 with base at Amazon
6A855 Solid State delay timer at Amazon
11-pin plug-in base at Amazon
Woods 32555 at Amazon
GE remote at Amazon
Wireless remote controls at Amazon
Replacement A23 battery at Amazon

Select recirculation pump
How to wire AH3-3 timer
See analog plug-in timers
See remote controls
Grundfos assorted manuals
Terminal strip and capacitor replacement/ pdf
Sample manuals below:
UP-043 installation photos
Choose pump size sheet
Grundfos product list

Laing AutoCirc Pump residental selection guide
Laing ACT install operation manual
Laing E1 E3 E10 series installation
Laing E1 Replacement Parts
Taco recirculation pumps manual
Taco timer sell sheet
Taco analog/digital timer install/program manual
Taco timer image

Troubleshoot recirculation pump

Misc manuals and links/ Resources

Grundfos recirculation pumps at Amazon

Will recirculation pump work on Tankless heater? Yes 4 GPM

If recirculation pump is rated maximum 4 gallon per minute, then assume it will work with tankless when everything is new and running smoothly ... and distance is not too great, and not too many elbows, not too many restrictions in the line, etc

Yes if you select correct recirculation pump.
How to set up Tankless recirculation
Rheem tankless recirculation illustation
Rheem tankless recirculation illustation 2
Rheem tankless point of use illustration
Rheem tankless recirculation illustration

   Read tankless manual thoroughly for minimum flow rate since flow rate appears in every tankless troubleshooting section.
   Flow rate and performance figures apply only when Tankless unit is new.
   Tankless cannot be exposed to hard water or parts will fail.
   As tankless ages, expect problems that are difficult to diagnose and expensive to repair.
   Re-circulation pumps are also susceptible to hard water and affects of age.

Read Bradford White side-by-side tankless vs tankless test results: "Tankless falls short of payback and cannot be exposed to hard water.'
Read side-by-side test results
Pro-n-con tankless heater
Read research pdf on Tankless/Tank efficiencies and softened water: Tankless cannot be exposed to hard water or parts fail 2 years.

How much does it cost to operate Autocirc?

Using the timer and running Autocirc 1 hour a day costs between $11 and $17 per year to operate.
Run autocirc 2 hours a day is $22-34 per year.
Run 12 hours a day costs $11-17 per month, or $132-204 per year.
This includes pump operation and additional time that water heater operates.

Calculate cost of running recirculation system

Autocirc is 33 watts each time motor operates
Timer runs 2 half-hour periods per day > yearly cost for re-circulation is $11-17 at Today's Rates

Two factors affect cost:

1) Pump cost: Pump uses approx 30 Watts = .030 Kw
Pump runs 1 hour per day = .030 Kwh per day
365 days x .030 Kwh = 10.95 Kwh per year
10.95 Kwh x Todays Rate 10 per Kwh (expect 30 tomorrow)= $1.95 per year

2) Water heater cost from re-heating water:
Amount of water: 1.2 gallons per 100 ft 1/2'" pipe (see calculation to right)

Amount of wasted heat:
Hot water travels to faucet anyway, so waste equals return length of pipe
Exact calculation would factor insulation, temperature of water, effect of home HVAC, efficiency of water heater, water heater thermostat setting, cost of energy.

Additional water heater Cost: Reheating 1-2 gallons uses .2 Kwh of electricity per event See chart
2 events per day x .2 Kwh  x 365 days per year = 146 Kwh per year
146 Kwh x 10 per Kwh = $15 per year for electric heater, $9 for gas

So $9-15 per year for reheating + $2 to run pump = $11-17 per year for re-circulation system that runs 1 hour per day assuming new equipment and optimal conditions, and today's low energy prices.

Heat loss during transmission is not factored: 100 ft of 1-1/2 in bare copper tubing results in a heat loss of 5300 Btu/h.
Calculate gallons inside 100' pipe:
1 gallon = 231 cu inches
Inner diameter of 1/2 pipe .54" so r radius = .27"
Area = πr

A = 3.14 x .27 x .27 = .229 sq in
100 ft = 1200 in
1200 in x .229 sq in = 274 cu in
274 cu in
231 cu in per gallon = 1.2 gal

3/4" pipe: r radius .37"
A = 3.14 x .37 x .37 = .429 sq in
100 ft = 1200 in
1200 in x .429 sq in = 514 cu in
cu in 231 cu in per gallon = 2.2 gal

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