How do I winterize a Rinnai RUS Model Series tankless water heater, such as the RUS65eP?

Winterizing a Rinnai RUS Model Series tankless water heater, such as the RUS65eP, is important to ensure it operates efficiently during the colder months and to prevent any damage from freezing temperatures. Here's a step-by-step guide to help you winterize your tankless water heater:

Turn Off the Power:
Begin by turning off the power supply to the tankless water heater. You can do this by locating the electrical disconnect switch or circuit breaker associated with the unit and switching it to the "Off" position. This step is crucial to prevent the unit from running without water, which can cause damage.
Shut Off the Gas Supply:
Next, locate the gas supply valve that feeds the tankless water heater and turn it off. This step ensures that no gas flows into the unit during the winterization process.
Turn Off the Water Supply:
Locate the cold-water supply valve that connects to the tankless water heater. Close this valve to stop the flow of water into the unit. Make sure the valve is fully closed to prevent any water from entering the heater.
Drain the Water Heater:
To prevent freezing and potential damage to the internal components of the tankless water heater, you'll need to drain any remaining water from the unit. Here's how to do it:
a. Connect a hose to the drain valve at the bottom of the water heater.
b. Open a hot water tap inside your home to allow air to enter the system.
c. Open the drain valve and let the water flow out. Ensure the hose is directed away from the unit and into a suitable drainage area.
d. Wait for all the water to drain out completely.
Remove and Store the Filter:
The Rinnai RUS Model Series tankless water heaters are equipped with a water filter to trap debris and impurities. Remove the filter housing and take out the filter element. Clean the filter thoroughly or replace it if necessary. Store the filter and housing in a dry, safe place for reinstallation when you restart the unit.
Protect the Unit from Freezing Temperatures:
If your tankless water heater is located in an area prone to freezing temperatures, it's essential to take additional steps to prevent freezing. You can:
a. Insulate the water heater and the water lines to provide some protection from the cold.
b. Install heat tape or heat cables on the water lines to keep them warm.
c. If possible, relocate the unit to a warmer location indoors or build an enclosure around it.
Keep the Unit Ventilated:
Ensure that the area where the tankless water heater is located remains well-ventilated during the winter months. Proper ventilation helps prevent moisture buildup and condensation inside the unit, which can lead to damage.
Regular Maintenance:
While your tankless water heater is not in use during the winter, it's a good time to perform any necessary maintenance tasks, such as descaling or cleaning, to ensure it operates efficiently when you restart it.
Prepare for Restart:
When spring arrives, reverse the winterization process by opening the cold-water supply valve, turning on the gas supply, and restoring power to the unit. Check for any leaks and ensure that the water heater is functioning correctly before resuming normal use.

By following these steps to winterize your Rinnai RUS Model Series tankless water heater, you can protect it from freezing temperatures and ensure it operates smoothly when you need hot water again. Proper maintenance and precautions can extend the life of your tankless water heater and help you avoid costly repairs.