Installation Instructions

whl-590 Rev. 003 Rel. 003 Date 3.22.18
23
COLD WATER INET
HOT WATER
OUTLET
Using the Optional Crossover (Thermal Bypass) Valve
In piping applications where a dedicated recirculation line is not available or too costly to install, the water heater can use a crossover (thermal
bypass) valve as a method of recirculation. The water heater uses its Internal Recirculation Pump, internal bypass line, and a crossover valve
installed between the hot and cold supply lines at the furthest xture in the plumbing line from the water heater to temporarily use the cold
water line to recirculate hot water through the system. A thermal bypass valve may be purchased at your local plumbing supplier.
When using an optional Crossover (Thermal Bypass) Valve, the Internal Recirculation Pump circulates hot water through the system to the
thermal bypass valve, where it is directed back to the water heater through the cold water line when hot water is not in use.
NOTE: When using an optional Crossover (Thermal Bypass) Valve, set the water heater Installer Parameter 0:RC to
- Preheat Mode, or
– Internal Recirculation Mode.
PIPING NOTES:
1. Minimum pipe size should match connection size. Upsize pipe accordingly if greater ow is required.
2. A thermal expansion tank suitable for potable water must be sized and installed within this piping system between the backow preventer
and the cold water inlet.
3. All circulators should have an integral ow check.
4. Drains and check valve between unit and storage tank will assist in purging air from system.
5. These drawings are meant to demonstrate system piping only. The installer is responsible for all equipment and detailing required by local
codes. In Massachusetts, you must install a vacuum relief valve per 248 CMR.
6. Mixing valve application is optional, but recommended to help prevent scalding.
7. Always shut o power to the water heater or isolate the heater from the system if ANY plumbing work is to be done. Running the water
heater without water will result in dry-ring.
Figure 15 - Water Heater with Thermal Bypass Valve - NOTE: There is a Built-In Flow Check in the Internal Recirculation Pump Loop