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 field 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 flooded 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.
1
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 fluttering 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 flow 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 (0
9
/05)
http://waterheatertimer.org/Water-heater-recirculation-system.html
