HWM-407CH-IOM (09/13)
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C. HWM Freeze Protection Thermostat
1. The freeze protection thermostat is factory installed. The thermostat wiring must be
connected when the HWM is installed. Run the wire through the electrical port in the top
panel of the Hydronic Water Module cabinet. After attaching the wire to the switch terminals,
run it into the Compressor Unit (using a control wiring port), in accordance with applicable
electrical codes.
2. Once the freeze protection switch wire leads are inside the Compressor Unit, locate the
lock-in relay in the Compressor Unit electric box.
3. Proceed to make the electrical connections as shown in the three steps illustrated in Figure
10e. Check all electrical connections to ensure a tight fit and good contact.
Figure 10e. Three-Step Electrical Installation for Freeze Protection Thermostat
4. Replace the cabinet cover to the HWM Hydronic Water Module.
5. If the water solution temperature drops to 38°F, the pre-set switch will trigger and cause the
lock-in relay to terminate power to the compressor. The system requires a manual restart.
6. Follow the Start-Up Procedure in Section 6.
