I've mentioned that I drain the hot water tank without pulling the drain plug. I now know why it works (on my '19 315RLTS--your camper may be different!).
At the bottom of this post is a basic diagram of the hot water system. The rest of this text will reference it.
Normally cold water flows through the blue line into the tank and hot water exits the tank (through the check valve) to the camper faucets upon demand. The Temperature and Pressure (T&P) valve is closed during normal operation. The T&P valve's purpose is it relieves excess temperature and pressure in a water heater if either reaches a critical point. A water heater is a closed system, and thermal expansion is an inescapable fact of both normal and abnormal water heater functioning. (https://www.thespruce.com/tandp-reli...heater-1825057)
To drain the heater:
1) Ensure that the gas or electric setting on the hot water heater is off
2) Disconnect city water from the camper and ensure the pump is off
3) Remove pressure from the camper's water system by opening a hot and cold faucet in the camper
4) Set the Nautilus panel set to Dry Camping but turn the red handle to the 9 o'clock position to isolate the hot water input water line.
-- This keeps the hot water heater from filling back up when the pump is turned on.
5) Open the blue (cold water) low point drain under the trailer
6) Open the T&P valve on the hot water heater (to let air in).
-- The water heater will drain completely, courtesy of Sir Isaac Newton (gravity). I've replaced the OEM's plugs in the low point drains with 1/4 turn valves, so opening the drain is quick and easy.
7) When the water stops flowing close the T&P valve and close the low point drain.
I've drained the hot water heater many, many times this way before starting a travel day. By draining the water it eliminates ~50 pounds of weight on the forward street side tire, the one carrying the most weight, on my 315RLTS.
Anticipating the questions:
a) The previously mentioned website states, Water heater manufacturers recommend regular checking of the T & P valve. To date the regular "checking" of the T&P valve on my water heater hasn't caused an issue. Obviously that is anecdotal at best, so YMMV.
b) Air will not enter through the hot water outlet on the unit because of the check valve. Opening a hot water faucet in the camper won't work--if air can't get in water won't flow out. (The valve's purpose is to keep water from flowing back into the water heater.)
As always, consider your own risk tolerance before duplicating what you read on the internet.
-Howard
At the bottom of this post is a basic diagram of the hot water system. The rest of this text will reference it.
Normally cold water flows through the blue line into the tank and hot water exits the tank (through the check valve) to the camper faucets upon demand. The Temperature and Pressure (T&P) valve is closed during normal operation. The T&P valve's purpose is it relieves excess temperature and pressure in a water heater if either reaches a critical point. A water heater is a closed system, and thermal expansion is an inescapable fact of both normal and abnormal water heater functioning. (https://www.thespruce.com/tandp-reli...heater-1825057)
To drain the heater:
1) Ensure that the gas or electric setting on the hot water heater is off
2) Disconnect city water from the camper and ensure the pump is off
3) Remove pressure from the camper's water system by opening a hot and cold faucet in the camper
4) Set the Nautilus panel set to Dry Camping but turn the red handle to the 9 o'clock position to isolate the hot water input water line.
-- This keeps the hot water heater from filling back up when the pump is turned on.
5) Open the blue (cold water) low point drain under the trailer
6) Open the T&P valve on the hot water heater (to let air in).
-- The water heater will drain completely, courtesy of Sir Isaac Newton (gravity). I've replaced the OEM's plugs in the low point drains with 1/4 turn valves, so opening the drain is quick and easy.
7) When the water stops flowing close the T&P valve and close the low point drain.
I've drained the hot water heater many, many times this way before starting a travel day. By draining the water it eliminates ~50 pounds of weight on the forward street side tire, the one carrying the most weight, on my 315RLTS.
Anticipating the questions:
a) The previously mentioned website states, Water heater manufacturers recommend regular checking of the T & P valve. To date the regular "checking" of the T&P valve on my water heater hasn't caused an issue. Obviously that is anecdotal at best, so YMMV.
b) Air will not enter through the hot water outlet on the unit because of the check valve. Opening a hot water faucet in the camper won't work--if air can't get in water won't flow out. (The valve's purpose is to keep water from flowing back into the water heater.)
As always, consider your own risk tolerance before duplicating what you read on the internet.
-Howard
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