To test and replace the flow switch:
1. Switch off the main electrical power supply to Therma-Flow
®
Plus.
2. Relieve pressure and fluid from the system as described in “4.3 Relieving Fluid
and Pressure from the System for Plumbing Repairs” on page 4-3.
3. If present, remove covers. See “4.2 Removing and Replacing ABS Covers to
Access Components” on page 4-1.
4. Loosen the bonnet nut from the flow switch body at the conduit. Remove the
bonnet ring. Rotate the switch bonnet counter-clockwise, clearing the conduit,
and remove the flow switch assembly from the unit body. You do not have to
remove the unit body from the system (see Figure. 4-13).
5. Ensure the shuttle assembly is clean and easily moves up and down the switch
tube. If necessary, remove retainer ring "A" for complete shuttle disassembly and
remove ring "B" to disassemble the disc only (see Figure. 4-13) to thoroughly
clean the assembly.
6. Remove the unilet cover (where the flow switch wire connections are made) by
turning the cover counter-clock wise to access the wire connections.
7. Make note of the wire connections and disconnect the flow switch wires (see Figure
2-4 Electrical Schematic on page 2-7). You may need to tie off the wires to re-pull
them through the conduit for reinstallation.
8. Perform a continuity test using the black and red (normally closed) leads for the
flow switch. The orange (normally open) lead is not used and is capped off with
a wire nut.
9. The flow switch will show continuity or closed circuit under normal conditions.
Should the test show otherwise, operate the switch through a cycle (lift and drop
the shuttle and test for continuity readings).
10. If the circuit remains closed, clean all particulate from the shuttle and magnet and
retest for continuity.
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