Our hot water heater (11 gallon) was drained of the antifreeze and filled with fresh water 4 months ago. We have actually gone through two fills of the water tanks and yet we still get a foul egg smell when the hot water is used. The unit was filled with some form or red antifreeze. the water is plenty hot. Is there some way to sanitize and clean the interior of the hot water tak without filling the 100 gallons of freshwater that our boat holds. I assume the tank is under pressure? Bleach, suggestions?
hot water odor
- Thread starter mr. Kempsville
- Start date
First, when ever you use water use the hot water tap for the most part. The reason is if you don't then the water will be stagnant in the heater and develop the bacteria that gives you the smell.
Second, put a couple of cups of bleach in your fresh water tank and then flush the entire tank through the hot water side. (I do one cup as part of spring commissioning for my total of 55 gallons I hold in my tank and heater). Then follow this up with 2-3 full fillings and flushings of the fresh water system through the hot water side.
Second, put a couple of cups of bleach in your fresh water tank and then flush the entire tank through the hot water side. (I do one cup as part of spring commissioning for my total of 55 gallons I hold in my tank and heater). Then follow this up with 2-3 full fillings and flushings of the fresh water system through the hot water side.
The smell is most often a result of a bad anode in the tank. Replace it and you should notice a difference, not to mention the protection it provides.
If your HWH has a replaceable anode, NOW is the time to replace it because that rotten egg smells indicates its now 'gone'.
If it doesnt have a replaceable anode, start selecting a new one now as this one will probably very soon have a hole in it and its going to start leaking. The rotten egg smell is the fresh water chamber releasing all the minerals and bio-deposits that have accumulated over the years .... the internal anode is now consumed and the walls and other inside components of the HWH are now become the anode.
If you dont have a galvanic isolator on your AC dockline connection, I strongly urge you to get one. Nowadays most HWH manufacturers will not honor any warrantee unless you have a galvanic isolator somewhere attached to your onboard AC system.
If it doesnt have a replaceable anode, start selecting a new one now as this one will probably very soon have a hole in it and its going to start leaking. The rotten egg smell is the fresh water chamber releasing all the minerals and bio-deposits that have accumulated over the years .... the internal anode is now consumed and the walls and other inside components of the HWH are now become the anode.
If you dont have a galvanic isolator on your AC dockline connection, I strongly urge you to get one. Nowadays most HWH manufacturers will not honor any warrantee unless you have a galvanic isolator somewhere attached to your onboard AC system.
You have sulfur bacteria living in your hot water tank, they feed on sulphate in the water and generate that hydrogen sulphide rotten-egg odor you are smelling. That antifreeze you put in the tank kept them fat and happy all winter long. These critters can survive in very hot water.
You need to shock chlorinate your hotwater tank. Most easy would be to shock your fresh water tank and immediately pump that water into your hotwater heater to do the same. Basically you use unscented household bleach to bring the water to either 10 mg/L chlorine for 24 hours or 50 mg/L chlorine for 6 hours. You do this by calculating the volume of water, and factoring the bleach concentration (on the bottle). Google up "shock chlorination calculator", there are some easy to use spreadsheets available.
After shock, flush your system and keep your water supply at 3-5 mg/L chlorine, that will prevent the re-colonization of sulfur bacteria in you HW tank. Don't put antifreeze in you HW tank, install a bypass on the intake and drain it during winterization.
You need to shock chlorinate your hotwater tank. Most easy would be to shock your fresh water tank and immediately pump that water into your hotwater heater to do the same. Basically you use unscented household bleach to bring the water to either 10 mg/L chlorine for 24 hours or 50 mg/L chlorine for 6 hours. You do this by calculating the volume of water, and factoring the bleach concentration (on the bottle). Google up "shock chlorination calculator", there are some easy to use spreadsheets available.
After shock, flush your system and keep your water supply at 3-5 mg/L chlorine, that will prevent the re-colonization of sulfur bacteria in you HW tank. Don't put antifreeze in you HW tank, install a bypass on the intake and drain it during winterization.
I went through this 2 years ago. I was getting the rotten egg smell and while my heater didn't have a replaceable anode it did have an anode that could be used in place of the drain. Of course the drain didn't come out easily and whole project was way harder than it had to be but eventually I got the drain out and the anode in. After about a month the odor didn't go away.
So I called the manufacturer. He said that the anode thing was mostly an internet myth. The tanks usually have other problems like blow heating elements or corrosion issues before the anode actually becomes an issue. He said to put a cup of bleach in the system and flush it out a couple of times. Followed that advice and the odor was gone in a week. Took the anode out when I winterized that year and haven't but it back in. I just do what I said above and I have had no issues.
That myth is how a lot of industrial and power generation heat transfer equipment is descaled/cleaned ... a 'reverse electrical current' is applied and all the fouling plus sulphur bearing biological deposits are 'released' ... and the 'rotten egg smell' is god-awful when its done.
Like I said, the manufacturer said it was mostly a myth. The process does happen. No one is denying that but what the manufacture said is that based on the size of the anodes typically installed you would need to have very heavy use of the water heater for many years with a non-typical municipal water chemistry. Same can be said of home water heaters. They usually rot out or stop working for other reasons before the anode becomes an issue.
There are bacteria/algae that can also cause the rotten egg smell and are typically more likely to be responsible for that odor on boats.
Again, this was information I got from the manufacturer and it has turned out to be correct in my case.
Fair winds,
Jesse
It would be useful to remember that there are A LOT of marine hot water heaters that; 1) Do not have an anode, and 2) Are well into their second decade of life. But they may periodically develop a H2S smell - a common problem with under-utilized water heaters that have been colonized by bacteria.