Xylem IM 16 Seal-less Centrifugal Canned Motor Pumps For Instant Hot Water Recirculating System (obsolete) - Manual (Page 6)

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Notes:
Keep The Hot Water Temperature Below 140ºF (60ºC): Higher temperatures can cause calcium and
magnesium elements to come out of solution and create solids which could not only cause damage to the
pump but also reduce water heater efficiency and premature failure of the water heater.
Hard Water Conditions: Use a water conditioner. Hard water can cause scale build-up and eventually reduce
the life of the pump and other system components.
Standard Dry Run Thermostat Operation
Each SM(T)-303/353 and UC(T)-303/353 model pump has a built-in 200ºF (93ºC) thermal cut-off in order
to protect against overheating, which could cause damage to the pump motor. In the event that
disruption of your immediate hot water supply is noticed it is possible that the pump has or is running dry
and the internal dry run thermal protector has shut down the pump motor. In this event, it is important
that the dry run condition be corrected (otherwise the pump will fail prematurely) by following the
procedure below:
1. Disconnect power to the pump motor.
2. Close the shut-off valves on each side of the pump.
3. Remove the pump motor/rotor assembly from the pump housing.
4. Dry off the pump motor/rotor assembly. Remove the rotor and check for any calcium build-up,
foreign matter or any signs of wear. If these signs are not present, put the rotor back in place on the
ceramic ball.
5. Hold the pump motor/rotor assembly upright and plug in the unit for about 10 seconds to see if the
rotor spins evenly and quietly. If the motor does not go on, allow a few more minutes for the
thermostat to reset as the unit cools down.
6. If the rotor spins properly, unplug the motor and reinstall the assembly into the pump housing.
7. Turn both shut-off valves to the on position, reconnect the electrical supply to the pump motor, and
be sure that air is properly purged from your system.
130ºF (54ºC) On-Off Thermostat Option “C”
Pumps with the letter “C” in the model are provided with a factory option “C” internal thermal cut-off
which automatically shuts the pump down when the temperature of the water passing through the
pump housing reaches 130ºF +/- 10ºF (54ºC +/- 4ºC) and turns the pump on at 110ºF +/- 10ºF (43ºC
+/- 4ºC) (SM/SMT 909/959-14 only).
Variable Setting On-Off Thermostat Option “R”
Pumps with the letter “R” in the model designation are provided with a factory installed internal thermal
cut-off with an adjustable On-Off temperature dial located on the outside of the motor. This dial can be
rotated by placing a thin screw driver in the dial slot which allows the pump to turn off automatically
when the water temperature passing through the pump housing reaches the dial setting selected
between 95ºF (35ºC) and 140ºF (60ºC). The pump will turn back on automatically when the water
temperature cools down to 10ºF (4ºC) below the set temperature (SM/SMT-303/353 only).
System Maintenance
• Do not attempt to lubricate the pump. The pump is self-lubricating.
• Prevent the pump from running dry.
• Flush the system of any debris and re-purge all air from the system in the event of any water supply
interruptions in plumbing line.
• Prevent heavy scale build-up by keeping the hot water temperature 140ºF (60ºC) or less. (only in US)
• Don’t over salt your water conditioner.
Replacement Parts
Please provide the following information when ordering: Model and Serial number and Part description
A - Housing
B - “O” Ring
C - Rotor Assembly
D - Motor Assembly
E - Screw Ring
A
B
C
D
E