Hot Water Tank Leak

[Mark&Colleen]

I discovered a small drip happening under the water heater area. The water pooling on the foot of my middle stabilizing leg.

After removing the wall in the storage area I discovered a leak at the hot water supply fitting at the top of the hot water tank.

I am assuming that I just need to replace that fitting?

I've searched the forum and didn't seem to find this exact issue.

Thanks
Mark

[TucsonJim]

I discovered a small drip happening under the water heater area. The water pooling on the foot of my middle stabilizing leg.

After removing the wall in the storage area I discovered a leak at the hot water supply fitting at the top of the hot water tank.

I am assuming that I just need to replace that fitting?

I've searched the forum and didn't seem to find this exact issue.

Thanks
Mark

That one is actually a pretty easy fix. It's not just a fitting. It is the outlet check valve. The plastic ones are not very reliable. You can purchase a new brass one from Amazon for $14. Simply unscrew the plastic hose fitting, unscrew the old check valve. Then, put a small dab of Teflon tape on the threads of the new fitting and reattach. Since you've already exposed the valve, it should just take a couple of minutes. Of course, make sure the water heater is cool, and drain it first.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Jim

[Mark&Colleen]

So glad to hear that!

Thanks so much Jim !!!!!

[ThePowells]

TucsonJim was perfect as always. when you replace that check valve, lookie all that soft hose and think about replacing it. Every connection where the soft hose is had the distinct probablility to be your next leak. That hose does not correctly fit PEX fittings. At a minimum, starting a PEX fitting line, fitting, clamp, and tool collection would be a great start.

[Lonestar]

That one is actually a pretty easy fix. It's not just a fitting. It is the outlet check valve. The plastic ones are not very reliable. You can purchase a new brass one from Amazon for $14. Simply unscrew the plastic hose fitting, unscrew the old check valve. Then, put a small dab of Teflon tape on the threads of the new fitting and reattach. Since you've already exposed the valve, it should just take a couple of minutes. Of course, make sure the water heater is cool, and drain it first.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Jim

I keep reading where the brass fitting will seize by corrosion if inserted into the aluminum tank of the water heater. I've never changed a valve out but it seems like the brass check valves have been used for years with no issue. Will the Teflon tape really help this issue in addition to preventing leaks?

The plastic valve on my water heater still appears to be in good shape. Is it possible that it can last for several years?

[TucsonJim]

I had one of the plastic check valves for many years without issues. The Teflon tape will not prevent galvanic corrosion. Typically, the tape will get cut when you install it. However, the tank on some units may be aluminum, but that doesn't mean the threads are. I don't know for sure.

Jim

[howson]

I keep reading where the brass fitting will seize by corrosion if inserted into the aluminum tank of the water heater. I've never changed a valve out but it seems like the brass check valves have been used for years with no issue. Will the Teflon tape really help this issue in addition to preventing leaks?

The plastic valve on my water heater still appears to be in good shape. Is it possible that it can last for several years?

I had a similar question before installing a brass check valve almost two years ago. I removed it at the one year mark to check for corrosion--there was no issue. Think about it--the T&P valve is brass and screwed into the tank and also doesn't seem to cause an issue, at least not one that is highlighted through multiple posts.

My knowledge of galvanic corrosion is just surface deep (ha!) so did some reading.

There's a PDF (I attached it to this post) from https://trianglefastener.com that has a simple-to-read chart (snip from the PDF posted below). Obviously the aluminum and brass are not as close together as one might like, but anecdotally I haven't read one thread where installing a brass check valve caused an issue.




Howard

[TedS]

You could use a pvc riser to isolate the materials, if really concerned.

[Cate&Rob]

There are four parts to a galvanic circuit. In this example . . . 1) Anode (aluminum), 2) Cathode (brass), 3) Electrical connection (aluminum and brass attached together) and 4) Electrolyte (water). Removing any one of the four will stop the galvanic action. If the water in the tank is pure, it will be a poor electrolyte and there will not be much galvanic action. A plastic part between the brass fitting and the aluminum tank will break the galvanic circuit.

I cannot explain why a brass pressure relief valve does not cause a problem other than perhaps because it is not usually submerged in the electrolyte (water)?. Some aluminum alloys are much better than others at resisting anodic corrosion . . . perhaps aluminum water tanks are made of this better material? Also, note that steel tanks use an aluminum or magnesium anode rod to absorb the galvanic corrosion in a replaceable part.

The anodic corrosion of the aluminum tank may not occur directly at the interface between the brass and the aluminum. In a welded aluminum structure, the weld is often an aluminum alloy more susceptible to anodic corrosion. When you flush an aluminum water heater, the white flakes that come out could be mineral deposits from the water or aluminum oxide from somewhere in the tank.

Rob

[Jlawles2]

I wonder if the Zinc corrosion protection rod is protecting the brass fittings/

[Cate&Rob]

I wonder if the Zinc corrosion protection rod is protecting the brass fittings/

Brass will be the cathode (non corroding side) of galvanic action between it and magnesium/zinc/aluminum which will be the anode (corroding side). Aluminum water heaters usually do not have anode rods . . . just a plastic plug. An anode rod for an aluminum tank would probably have to be magnesium.

Rob

[howson]

Aluminum water heaters usually do not have anode rods . . . just a plastic plug. An anode rod for an aluminum tank would probably have to be magnesium.

I was told at school that the aluminum tank was itself the "anode rod" in the Atwood (Dometic) water heater--it will, over time, consume itself.

[Cate&Rob]

I was told at school that the aluminum tank was itself the "anode rod" in the Atwood (Dometic) water heater--it will, over time, consume itself.

Hi Howard,

This is an interesting perspective from a manufacturer . . . but makes complete sense. Aluminum is less noble than most other materials used in, or attached to, the aluminum tank.

There is a way around this . . . although it would not be inexpensive. As a long time owner of a large welded aluminum boat, I was always keenly aware that my boat could easily become the anode for the entire harbour. This meant steps to electrically isolate my boat from anything else (isolation transformer on the shore power) and a number of magnesium anodes on the aluminum hull. Magnesium being less noble than aluminum. Following this logic, a magnesium anode rod would protect an aluminum tank from galvanic corrosion. The question is . . . where would we find one of these?

Edit: Turns out . . . not that difficult to find. https://www.amazon.com/Water-Heater-...62110214&psc=1

Rob

[Lonestar]

I had a similar question before installing a brass check valve almost two years ago. I removed it at the one year mark to check for corrosion--there was no issue. Think about it--the T&P valve is brass and screwed into the tank and also doesn't seem to cause an issue, at least not one that is highlighted through multiple posts.

My knowledge of galvanic corrosion is just surface deep (ha!) so did some reading.

There's a PDF (I attached it to this post) from https://trianglefastener.com that has a simple-to-read chart (snip from the PDF posted below). Obviously the aluminum and brass are not as close together as one might like, but anecdotally I haven't read one thread where installing a brass check valve caused an issue.


Howard

howson Very good information. A goofy question: would any type of a bonding strip between the brass and the aluminum tank take some of the corrosive pressure off of the threads?

I don't know that I have ever known anyone that had to replace the T&P valve, so don't really know if there is an issue there. Maybe if the check valve were removed and cleaned every year there might never be a problem, but that would be tough due to the location on most water heaters.

Probably isolating the valve like TedS mentioned with a riser would be a good solution. Instead of pvc, I think you would need cpvc. pvc maxes out at 100 degrees F. Don't most RV water heaters go higher than that?

[TedS]

That pvc fitting has a 140F rating. Higher would be better.

The T&P valve may be an aluminum bronze alloy, less susceptible than brass to the galvanic corrosion.