Laing Sm-303-b Installation instructions

Installation & Operating Manual

Please read this manual carefully before attempting to install, operate or maintain the product described. Failure to comply

with the information provided in this manual could result in personal injury and/or property damage. Retain this manual

for future reference.

Seal-less Centrifugal

Canned Motor Pumps

For Instant Hot Water Recirculating Systems

About LAING Pumps

Laing Recirc®pumps have only one moving

part--the rotor/impeller. The motor creates an

electromagnetic eld that balances and spins the

rotor/impeller on a stationary bearing ball inside

the pump cavity. The motor is fully encapsulated in

resin, has no moving shafts or seals, and elimi-

nates conventional wear that can generate noise.

Like all seal-less centrifugal circulators, the pump

cannot be run without water lubricating the bearing.

The pump housing must be ooded before start-up

and water must be maintained in the system during

pump operation. The unique leak-proof integra-

tion of the motor and pump housing eliminates the

need for conventional mechanical seals or other

shaft sealing devices. These components are self-

lubricating and require no external lubrication.

WARRANTY

Laing recirculation pumps are warranted against defects in materials and workmanship for 24 months from

the date of manufacture (see mfg. date label on pump) or twelve (12) months from date of user purchase,

with proof of purchase, whichever is later. In order to receive warranty considerations, the product must be

returned prepaid to the company from which it was originally purchased. If the pump is found defective, the

pump will be replaced or in the case of wholesale customers, appropriate purchase credit will be issued.

Prior to returning any defective pump to Laing for warranty consideration, contact the Laing factory for

an RMA tracking number. Any claim for consequential damages resulting from a pump malfunction is not

covered by the Laing warranty. Additional warranty details are available on request. (1/02)

SM-303-B

Models: SM-303-B

SMT-303-B

SM-909-B-14

SMT-909-B-14

UC-303-B

UCT-303-B

SMT-303-B

with 24 hour timer

SM-909-B-14 SMT-909-B-14

with 24 hour timer

Trouble Shooting

Noise in the System: The pump should be virtually noiseless during operation. The ro-

tor may make a brief but hardly perceptible uttering noise immediately after the pump is

turned off. During normal operation, an occasional air bubble may pass through the pump

housing causing a momentary gurgling noise. However, if noise at the pump persists for

any prolonged period, correct the problem (see below).

• The check valve is mistakenly installed on the inlet side of pump or in the wrong direction.

• The inlet side shut-off valve is closed or clogged.

• There is air is trapped in the pump housing (turn the pump on and off several times to see

if the air pocket can be “bumped” out of the pump and if not, then open the hose bib

for manual venting).

• There is debris blocking the rotor.

• The rotor bearing has worn due to dry running causing the rotor to wobble during

operation.

• If the return line connects to the cold water supply at the top of water heater, the warm

water may be creating back pressure in the cold supply line. If so, add a check valve on

the cold supply line above the return line tee connector.

Pump Operating Intermittently or Not at All:

• No power to the pump.

• There is debris or foreign matter in the pump.

• The thermostat is not functioning properly (see page 6 on thermostat operation). If

wanted, the thermostat may be easily disconnected. Contact the Laing factory for

details.

Water Taking Too Long to Get to Faucet:

• The hot water supply from the water heater is exhausted.

• The faucet involved may be on a branch line off the main hot water supply line in

which case there may be a slightly longer wait for hot water to arrive than at

faucets directly off the main supply line.

• The check valve is installed backwards.

• The pump is not operating.

• The timer is not operating properly.

Signs of Dry Run:

Dry run results from inadequate water supply to the pump, which prevents lubrication of

the bearing ball. It may be caused by operating the pump without water in the plumbing

lines, which may occur with frozen pipes, or by failing to turn the pump off when the sys-

tem is drained for servicing. It can also occur as the result of large air bubbles collecting in

the pump housing and preventing the ow of water over the bearing ball. If the problem is

air in the system, check that the air vent is functioning, that the system is properly purged

of air and that the pump and various system components are installed in accordance with

the diagrams shown on page 3.

Laing Thermotech, Inc.

830 Bay Boulevard, Suite 101, Chula Vista, CA 91911

Phone: (619) 575-7466 Fax: (619) 575-2739

www.lainginc.com • www.autocirc.com

UC-303-B UCT-303-B

with 24

hour timer

IM-16 (09/05)

http://waterheatertimer.org/Water-heater-recirculation-system.html

Hose Bib

Laing

Ultracirc

Pump

Hot

Water

Heater

Air

Vent

Return Line

Hose Bib

Laing

Ultracirc

Pump

Air Vent

Hot

Water

Heater

Installation and Start Up

1. Select the sink under which to connect the recirculation line (the sink where the

hot water takes longest to arrive which is usually the sink farthest from the water heater).

2. Plan your installation. Decide on the course of the recirculation pipe (also determin-

ing the length of the pipe required) and whether the return line should be connected to the

water heater cold water inlet line (tee tting required) or to the bottom water heater drain

valve (“Y” type tting required to t to existing drain valve outlet). See gure 1 and 2 for

the installation schematic.

Above diagrams are for single line returns only. For multiple branched supply line installa-

tions, a recirculation line should be installed for each branch.

Note: The pump must always be installed below the water level of water heater so

that the pump ow is always upward or directly horizontal and not downward. Do

not mount the pump above the water heater.

3. Purchase materials required.

• Laing Recirc® Pump (SM-303/UC-303 or SM-909) • (1) 1/2” or 3/4” swing check valve

• Copper pipe or tubing (not required on UC/UCT models)

• Tee for under sink connect • (1) 1/2” or 3/4” hose bib

• Tee or “Y” tting connection to water heater • (1) Auto air vent

• (2) 1/2” or 3/4” shut-off valves (not required on • Misc. nipples and ttings

UC/UCT models) • Pipe insulation

A. Return into Cold Water Line at Top of Water

Heater g. 1

B. Return to Drain Valve at Bottom of Water

Heater g. 2

About Recirculation Systems

Air in the System: A properly installed system should include a method of automatically venting

the air that enters the water supply line during use. Air enters the system each time fresh, cold

water is introduced into the hot water heater. Air may also enter the system any time a plumbing

line is opened, for instance during a faucet change or adding a sprinkler system.

Water Pressure: A recirculating system is a pressurized system operating at the city water pres-

sure, as determined by the pressure regulator on your line, or by a well pump, if you are on a well

system. In most residential plumbing systems, water pressure is set at 35 psi and above. Below

35 psi, water pressure may not be sufcient to ll the pipe diameter, leaving space for air to ac-

cumulate in the lines. If your system pressure is less than 35 psi, use the next larger pump on the

Pump Selection Guide.

Multiple Floors: Because the system is pressurized, the number of oors in a home is not taken

into consideration in sizing the circulating pump. The pump has only to produce continuous ow at

a pressure sufcient to overcome the friction losses created by the piping in the house water sup-

ply line and the return line.

Oversized Pumps: Pumps should not be so large as to produce ow rates that may eventually

erode holes in the pipes. According to the Copper Development Association, excessive erosion

occurs at a velocity of about 5 ft. per second and higher; or about 4 GPM in 1/2” Type M copper

pipe; and 8 GPM in 3/4” pipe. Use the recommended recirculation line size shown in the Pump

Selection Guide. Laing pumps are sized so that ow velocities are well below these limits.

Pump Selection Guide: The Laing SM and UC 303 models are designed to handle the recircula-

tion requirements of residences with a pipe loop (the total length of hot water supply line plus the

recirculation line) up to 250 feet while the SM-909 model pump is designed to handle the circula-

tion requirements of residences and small apartment complexes with pipe loop runs to 700 or 1000

feet. The chart below provides a simple rule of thumb to help you match the pump to your system.

Housing Codes:

BS 1/2 - 1/2” Sweat

BT 1/2 - 1/2” Female NPT

BS 3/4 - 3/4” Sweat

BF - Flanged

Total Pipe Recirc

Pump Model Building Size Loop (Supply Line Pipe

& Return) Size

SM/SMT-303 (BS 1/2” or BT 1/2”), UC/UCT-303, Residential 250 ft. 1/2”

SM/SMT-909-B-14 (BS 1/2” or BS 3/4”), UC/UCT-909-14

Residential 700 ft. 1/2” or 3/4”

SM/SMT-909-B-18, SM/SMT-909-B-26 (BS 3/4” or BF),

Residential 1000 ft. 3/4”

UC/UCT-909-18, UC/UCT-909-26

Pump Selection Guide

Pump Data

Model HP RPM Watt Volt Phase Cycle Amps

SM/SMT-303, UC/UCT-303 1/150 3400 33 115 1 60 0.3

SM/SMT-909-14, UC/UCT-909-14 1/50 3400 65 115 1 60 0.6

SM/SMT-909-18, UC/UCT-909-18 1/20 3400 98 115 1 60 0.9

SM/SMT-909-26, UC/UCT-909-26

About Plastic Piping

In many cities throughout the U.S. Polybutylene and CPVC plastic piping is approved for use in

residential water systems for both hot and cold water supply lines. However, it is not clear as to

the plastic pipe manufacturer’s position relative to the approved use of their pipe when there is

always hot water in the hot water lines such as would be the case with a hot water recirculation

system. Evidently having hot water in the lines intermittently is acceptable (timer operated pump)

but not constantly. As a result Laing cannot offer any recommendations for or against the use of

plastic pipe until such time as the plastic pipe manufacturers themselves establish a clear position

in this regard. Check your local codes on the permissibility of plastic piping for your hot water

recirculation system.

Note: provide upward slope of piping from the

pump to the water heater.

shut-off

valve

Laing Recirc

Pump

shut-off

Air Vent

HOT WATER HEATER

hot

supply

line

cold

supply

line

check valve

hose bib

A. Return into Cold Water Line at Top of Water

Heater g. 3

B. Return to Drain Valve at Bottom of Water

Heater g. 4

SM/SMT Models

UC/UCT Models