Stinky hot water??

Stu Jackson · Feb 12, 2012

You might find this thread pertinent: http://forums.catalina.sailboatowners.com/showthread.php?t=138000

Read the link provided.

HillbillyWanderer · Feb 12, 2012

The water in your holding tank has been in there too long. I would not leave water in holding tank at max 3 weeks after that you rest the water starting to smell. Have a houseboat with holding tank use to stay on it used water all the time in holding tank so it stayed freash. Got married, forgot how to even drive a boat.

When happened to me had to flush tanks and pour some clorox in then drain again. Done it twice I think. Im sure they are better soultions out there but thats what I done.

artboas · Feb 12, 2012

Here's my guess

eianm said:
went out yestersday for the first time in about 5 weeks on our H42 and when turning on the hot water to wash up- it stank badly/strongly of rotten egg gas type smell. Cold water totally odourless- and hot water, after it ran cold became virtually odourless has anyone had a similar experience and if so what was cause and fix? After we ran back to the dock the hot water ( heated up again during running) had the same , but not as strong odour .
thanks
Eian

There is a heat exchanger in your hot water tank where hot engine coolant runs through. I have a sneaky suspicion you may have a heat exchanger leak.
It sort of sounds right to me based on the circumstances.

walmsleyc · Feb 12, 2012

Anode?

It is mentioned a number of times in the archives, and elsewhere on the net, that the smell could be from the anode that has deteriorated and has part of the iron core exposed. I have had a sulphur smell from ONLY my hot water most seasons except for the last few. I ordered a new anode, but have never installed it. I have been more careful commissioning the water system in the past few years, and my water has been significantly better.

I just did some checking on the Seaward manuals, and it appears that to use one of the anodes, you need to remove the drain valve, and replace it with the anode (and NOT put the drain back in). If I read the instructions correctly, then this suggests that:

1) I still have my drain valve on my heater, so I must not have an anode installed, and thus, the anode could not have been part of my smell problem, and
2) if I do install the anode (maybe not needed because that couldn't have been the cause of the smell), then to drain the tank (which I do every fall), and would have to unscrew the anode and let water wash over everything as opposed to using the drain valve to let it drain through a hose to the bilge.

Can anyone confirm that my thinking is correct on this one?

Chris

Don S/V ILLusion · Feb 12, 2012

That's the answer!

walmsleyc said:
Anode?

It is mentioned a number of times in the archives, and elsewhere on the net, that the smell could be from the anode that has deteriorated and has part of the iron core exposed. I have had a sulphur smell from ONLY my hot water most seasons except for the last few. I ordered a new anode, but have never installed it. I have been more careful commissioning the water system in the past few years, and my water has been significantly better.

I just did some checking on the Seaward manuals, and it appears that to use one of the anodes, you need to remove the drain valve, and replace it with the anode (and NOT put the drain back in). If I read the instructions correctly, then this suggests that:

1) I still have my drain valve on my heater, so I must not have an anode installed, and thus, the anode could not have been part of my smell problem, and
2) if I do install the anode (maybe not needed because that couldn't have been the cause of the smell), then to drain the tank (which I do every fall), and would have to unscrew the anode and let water wash over everything as opposed to using the drain valve to let it drain through a hose to the bilge.

Can anyone confirm that my thinking is correct on this one?

Chris

Peggie Hall HeadMistress · Feb 12, 2012

When a Rotten egg taste/odor is in HOT water ONLY

The odds are 100-1 that a failed anode is the reason.
In glass lined water heater tanks, the anode is a magnesium rod, about 3/4" in diameter that is attached to the inside of the hot water "out" nipple, via a plastic coupling. It is electrically isolated from the fittings and from the tank. It extends all the way across the inside of the tank, stopping just short of the other side. There is an iron rod in the center of the magnesium that supports it, the iron being stronger than the magnesium. As the magnesium is eaten away and the iron rod exposed, there's a chemical reaction between the water, the iron and the magnesium that causes the "rotten egg" smell. Replacing the anode and flushing out the tank will usually make the foul smell go away.

However, low priced water heaters often have anodized aluminum or steel tanks that don't have a replaceable anode....when the anodizing wears off the only cure is new water heater.

walmsleyc · Feb 12, 2012

According the "Seaward Water Heat Manual.pdf" (attached), the heaters don't come with the anode, and if you install it, you lose your drain valve. When I received my anode from Seaward (it looks exactly like the picture in the manual), I couldn't figure out where to install it. The manual suggests that I probably don't have one currently installed because I still have a functioning drain valve.

Here is an excerpt from elsewhere on the web:

How is hydrogen sulfide gas produced in a water heater?
A water heater can provide an ideal environment for the conversion of sulfate to hydrogen sulfide gas. The water heater can produce hydrogen sulfide gas in two ways - creating a warm environment where sulfur bacteria can live, and sustaining a reaction between sulfate in the water and the water heater anode. A water heater usually contains a metal rod called an "anode," which is installed to reduce corrosion of the water heater tank. The anode is usually made of magnesium metal, which can supply electrons that aid in the conversion of sulfate to hydrogen sulfide gas. The anode is 1/2 to 3/4 inches in diameter and 30 to 40 inches long.

(link here) Further down on the web page, it is suggest to remote the anode altogether, or to replace it with a non-magnesium anode to avoid the problem.

Also, from this site:

Sulfate which is a combination of sulfur and oxygen (SO4) exists as a dissolved salt in the water. As such it is colorless and odorless. It is not to be confused with the gas in the water that causes a rotten egg odor. This is a combination of Hydrogen and Sulfur (H2S). Removal technology is totally different for the two forms of sulfur. Sulfate will react with aluminum and magnesium( what anode rods inside water heaters are made of) and produce that nasty smell in the hot water only.

This implies that the magnesium is the contributor to the Sulphur smell, and if true, then replacing the anode would either have no effect, or in fact make it worse (if you either don't already have an anode, or it has totally dissolved).

What is one to make of all this? It is not clear to me that:

My heater currently has an anode at all
Thus, the iron core is not causing "my" smell problem, and further
That the anode logic (quoted below) seems to only cover the case where "iron bacteria" and are feeding off of the dissolved iron from the failed anode, but a perfectly good anode can also contribute to sulphur smell too (checking your anode might let you distinguish between the two).

Has anyone actually inspected or replaced an anode on a Seaward heater? Does it preclude the drain valve?

(Note: my heater in on a 87 Hunter Legend, so may differ from the manual).

Peggie Hall-HeadMistress said:
The odds are 100-1 that a failed anode is the reason.
In glass lined water heater tanks, the anode is a magnesium rod, about 3/4" in diameter that is attached to the inside of the hot water "out" nipple, via a plastic coupling. It is electrically isolated from the fittings and from the tank. It extends all the way across the inside of the tank, stopping just short of the other side. There is an iron rod in the center of the magnesium that supports it, the iron being stronger than the magnesium. As the magnesium is eaten away and the iron rod exposed, there's a chemical reaction between the water, the iron and the magnesium that causes the "rotten egg" smell. Replacing the anode and flushing out the tank will usually make the foul smell go away.

However, low priced water heaters often have anodized aluminum or steel tanks that don't have a replaceable anode....when the anodizing wears off the only cure is new water heater.

orion · Feb 13, 2012

I have a seaward 6 gallon water heater. Seaward says that the original anode is probably dissolved and the solution is to take the drain plug out and screw in the magnesium anode. You lose the drain plug. But so what. At the end of the season take it out and let the water drain out of the heater and into the bilge. I did this and it removed the rotten egg smell, This was a very inexpensive fix ($15). Do it you will be happy and not have to spend a lot on a new heater.

walmsleyc · Feb 13, 2012

That's interesting! You're saying that the heaters have a built in anode (non-replaceable), and when that goes, then you can buy a new anode from them, but you have to install it instead of the drain port.

If that is true, then am I still missing something? That would leave the original anode, possibly dissolved down to the iron core, still in the heater, and still likely to cause a sulphur smell through either iron bacteria, if that were the cause, or because the addition of the new anode would facilitate the conversion of sulphates into H2S.

(I know I'm nit picking on this stuff, but it's not yet clear to me in the case of these particular heaters, how replacing the anode would resolve the issue, though it would certainly help continue to protect the heater from corrosion).

Chris

kloudie1 · Feb 13, 2012

Chris, My Seaward literature notes that it does not have an anode in it but if you use the heater in a place that has corrosive dissolved salts in the water, you can add an anode by substituting it for the drain valve.

walmsleyc · Feb 13, 2012

Well, the possibilities seems to be:
- Heaters do NOT come by default with an anode (noted by kloudie1)
- Heaters DO come with an anode, but it is not replaceable (noted by orion)
- You can add an anode in place of the drain valve on Seaward heaters (maybe others)
- Raritan may have replaceable anodes.

Potential Causes of Smell:
- Iron Bacteria
- Conversion of Sulphate to H2S
- Other bacteria growing in that part of your system (hot water tank).

So, for a Seaward heaters, adding an anode in place of the drain valve should not affect the sulphur smell because:
- If there was a non-replaceable corroded anode inside,
then it will still be there and still cause problems.
- If there wasn't a anode already in the heater, adding
one will not prevent sulphur smell, and might, if sulphate
content was high in the water, contribute to H2S be formed and thus create a sulphur smell.

For Raritan heaters with a replaceable anode, replacing a corroded anode might eliminate the iron from the old anode, and remedy the sulphur smell.

The best I can summarize is that
- A sulphur smell could be due to a corroded anode. You should replace it or add a new
one in order to prevent corrosion in your tank, but it wont improve the smell problem.
- In some cases, a good condition magnesium anode could be contributing to the smell.
- Proper commissioning of the water system and avoiding having water sit in the tanks
and heater will probably eliminate most smells.

Chris

kloudie1 · Feb 13, 2012

walmsleyc · Feb 19, 2012

That's good information, and supports my experience. I did not add/replace an anode, but I did do a much better job of commissioning my tanks each spring, and the smell is virtually gone.

Do beware that if you have aluminum tanks, leaving too much chlorine in them for too long can accelerate corrosion. Take a look at this thread for a good discussion on that.

Chris

Stinky hot water??

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