Adding Drain Valve to Atwood Water Heater

At wood recommends that the tank be flushed periodically to remove sediment that results from the aluminum cladding doing its job. I flush mine out using a flushing rod I picked up somewhere. If you just drain your tank, the crud sits in the bottom of the tank. You need to agitate the sediment. When I flush it I get a lot of aluminum oxide that comes out of the tank.

The sulfer smell is not from bacteria, but from the result of the cladding doing its job.

I clipped this from the Atwood manual:

FLUSHING YOUR WATER HEATER TO REMOVE THE ROTTEN EGG ODOR

Hydrogen sulfide can result when the protective cladding on the interior of the tank is doing its’ job by preventing corrosion and therefore premature tank failure. The electro galvanic action of the cladding material releases hydrogen from the water. If sulfur or any of its’ combinations are present in the water the two will combine and produce hydrogen sulfide. This compound produces the “rotten egg odor”. Hydrogen sulfide can also be present in your fresh water supply. It is the product of the decay of animal matter and as little as one mg/liter can cause a perceptible odor. Smell the water before starting the flushing procedure. If your fresh water has the rotten egg odor, you will need to find another source of fresh water before flushing and refilling the entire water storage system.

1. Turn off your main water supply - your pump or your water hook up source.

2. Drain your water heater tank. Due to the location of the drain plug, approximately two quarts of water will remain in the bottom of the tank. If while draining the unit you note that it is flowing sporadically or trickling, instead of flowing steadily, we recommend one of two things. First open your pressure-temperature relief valve to allow air into the tank and secondly, take a small gauge wire or coat hanger device and prod through the drain opening to eliminate any obstructions.

3. After thoroughly draining the tank, to remove the smell flush the entire system from water inlet all the way to holding tank.

For flush use — four parts vinegar mixed to two parts water. If you elect to use air pressure, it may be applied either through the inlet or outlet on the rear of the tank or applied through the pressure-temperature relief valve part. Remove the pressure-temperature relief valve and insert your air pressure
through the pressure-temperature relief valve coupling. In either case, with the drain valve open, the air pressure will force the remaining water out of the unit.
If air pressure is unavailable, your unit can be flushed with fresh water. Fresh water should be pumped into the tank either with the onboard pump or external water pressure. External pressure may be hosed into the unit either through the inlet or outlet found on the rear of the tank or the pressure-temperature relief valve coupling located on the front of the unit. Continue this flushing process for approximately five minutes allowing ample time for the fresh water to agitate the stagnant water on the bottom of the tank and forcing the deposits through the drain opening.

4. Upon completion of the steps above, replace the drain plug and the pressure-temperature relief valve.

The Atwood water heater is designed for use in a Recreation Vehicle. If you use your vehicle frequently or for long periods of
time, flushing the water heater several times a year will prolong the life of the storage tank.

I drain my water heater once a year when winterizing. I added the pit cock like from Camping World shown above.

I really like the idea with the added hose to get the water away from the water heater. I might do that mod to my setup.

I am also thinking about adding an electric heater core to my off-road POPUP setup so I can maybe run my hot water heater off my INVERTER when camping off the power grid. This will go along with my HYDRONIC HEATER MODs using my hot water heater for hot water source. I may run out of an easy way to drain my hot water for winterizing... My HYDRONIC HEATER MOD will include a 12VDC water pump so guess I can tap my water line there and just install my pit cock there for draining.

I really like wa8yxm's long hose mod... neato...

Roy Ken

I use a turkey baster with a short section of clear hose to suck out that last bit of water that will not drain on it's own.

The Atwood water heaters also do not empty completely with the drain plug removed. 2 quarts of water remain in the tank. Not enough to cause a problem if it freezes sold but enough to grow bacteria. I add 1 tsp. of household bleach (which is a 5% solution already)for every 10 gallons in the freshwater tank and then after draining the hot water I run the pump to get the treated water into the hot water tank. It can sit for months and not have problems with the bacteria.

Problem is specific to the hot water tank as it does not have air inside and this is a good environment for the type of anaerobic bacteria that reduces sulfates in the water to produce the gas one smells at the tap.

We were experiencing the problem when the RV would sit unused for several months. The water in the tank was not exposed to the air and at ambient temps of around 65-70 degrees the bacteria thrived. Bleach is a simple and inexpensive fix and one recommended by FEMA for long term drinking water storage.

dons2346 wrote:
I don't drain the water heater. The only time I remove the plastic plug is to flush it.

Why drain the heater after every use?

Anerobic bateria and that wonderful sulfur smell that results with water sitting in a closed tank. If the hot water heater is going to sit for more than a few weeks I will drain it completely.

These approaches with a hose are simply brilliant.

path1 wrote:
http://www.campingworld.com/shopping/item/brass-water-heater-drain-valve-38/49073

What is a matter with one of these?

Nothing wrong with it. But the above setup with flexible hose keeps the water from running into the water heater compartment and/or down the side of the rig.
I made one similar to it.

http://www.campingworld.com/shopping/item/brass-water-heater-drain-valve-38/49073

What is a matter with one of these?

A couple of things about the drain hose in my pictures.

1. When winterizing, I remove the hose and use a cleaning wand to rinse the debris out of the water heater. I then put the regular nylon plug back in finger tight to keep the bugs out.

2. It takes a long time to drain the water heater by just opening the valve at the end of the hose, since the air has go back up the hose. If I'm in a hurry to get the water heater emptied, I open the pressure relief valve to allow air to get in that way.

I will also go with the hose and valve next time. I have a valve connected directly to tank now.



Even those who want to use a cleaning wand at the end of the season. It is no more difficult to remove the hose adapter than the plastic plug.

I drain and flush my tank after every trip. Bacteria grows best at about 98 f. After turning off a water heater the water is at or near this temperature for a long long time. Makes sense to get rid of the warm water and any bacteria that has grown.

CloudDriver wrote:
My drain setup

I like it, all plastic too.. Very good. It addressed each and every complaint I have about the Attwood drain.. Great job.. I'll copy it the next time I have to re-do my valve.