Water heater winterizing & system knowledge

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This is my first winter having a boat with a water heater, and I need a little better understanding of a couple things. The water heater is a 6 gallon Seaward.

In preparation for the upcoming winter, I am in the process of winterizing the water systems on board. I'm considering draining and bypassing the water heater, but here's the questions.... What if I still go out on nice days, and the water heater is empty from being drained? Will this cause damage to the water heater's internal heat exchanger? It seems to me that the possibility exists that the heat exchanger could overheat with no liquid medium present after being drained. I assume that if the heat exchanger overheats, it could also damage the water heater in general, right? What's the scoop? After emptying the water heater should I skip the bypass, and add antifreeze to it if I expect to be running engines?

Also, I have Volvo 8.1 OSI freshwater cooled engines (FW-block only). Does the water going through the water heater's heat exchanger come from the freshwater, or raw water side of the engine? Not being a skilled mechanic, I'm not certain of what the origin of the water is when looking at the engine's "plumbing".

Thanks in advance.

GW
 
You won't cause damage to the heater if you run the boat with it empty.

Plus you won't have any issues with it overheating.

The water heater has anti-freeze (from the motor) running thru the hoses to heat it from the motors.

Do not let anti-freeze (pink) get into the water heater.

Bypass the water heater and enjoy your last days on the water!!!

Jonathan
 
Thanks Jonathan,

Another dumb question.........

The drain valve on the water heater is not at the very bottom of the unit, but a couple inches above the bottom of the chassis. When drained, is all the water removed, or is there a need to remove the remains via other means?

Also, just to understand a little better.......

You mentioned not to allow pink anti-freeze into the water heater. Is it harmful to the heater, or is the reason simply because it is difficult to completly remove from the hot water side come spring time?

Thanks again,

GW
 
Leaving a little water in the heater won't be a problem at all. As long as it has room to expand you'll be fine.

It can do damage to the heater, plus it's a waste of money to fill it with pink.

And yes it would be a pain to get rid of all of it in the spring.

I use an air compressor to blow out all of the water lines on my boat.

I don't use pink in the water system anymore.

If you decide to use air, you won't even have to bypass the water heater, just drain it, seal it back up and then proceed to blow out the cold side and then the hot side.

I do this twice to make sure I got it all.

Do you have a dock side water connection???
 
I'll certainly entertain the idea of utilizing air to purge the system of water. If not, I'll just bypass the water heater. I've seen a permanant plumbing fixture kit to enable bypass by merely turning a valve, which alleviates the need to disconnect and re-connect hoses every year. If I go the bypass route, I think I will do that.

As for the air purge route, yes I do have a dockside water connection. I assume this is where one would inject air. That said, where do you get the fitting? Also, what PSI is sufficient for the job, yet at the same time, not harmful to the plumbing lines and fixtures? Is a pancake compressor sufficient in terms of air volume?

Thanks Jonathan.
 
It looks like the drain vavle is not at the bottom but the way the water hear is constructed is that there is a round tank inside the square box. The rest of the space has insulation in it. The drain valve is pretty close to the bottom. It won't empty completely but even the Atwood manual says that it is allright to leave a small amount of water in there.
 
Robyn:

What "damage" can the pink A/F do the the tank? Beyond the need to flush well in the spring of course.
 
Many people at my marina don't bypass the water heater, the only effect being having to pay for another few gallons of antifreeze. I did the same last year, just let the water heater fill up with antifreeze when I winterized my water system. There was absolutely no "damage" or any other consequence of doing so, other than I had to give it a good flush by running plenty of freshwater through it to get rid of the antifreeze smell in the spring.

I've never heard of damage to a water heater as a result of antifreeze, that is new to me also. I have heard that the filter may foul and need to be replaced, although that was not the case for me last year.

This year I did the same thing but ended up draining the pink from the heater right into the bilge after I was done winterizing the water system.
 
You could also catch the antifreeze as it comes out of the heater and use it for one of the other systems. But it's so easy to bypass. My heater is 11 gallons.
 
People here on this forum have reported that it ruins the anode in the heater and is the reason for rotten egg smeling water. I don't know, my water will do that if I don't use it for a long time and I haven't put antifreeze in the tank.
 
Funny thing is I had the rotten egg smell at a point last year when the boat had never been winterized. After letting it sit with the pink stuff in during winter, and flushing with a bleach mixture solution at the start of spring, I had no rotten egg smell at all this year.

I'm not saying that the pink stuff helped, but it certainly didn't make it any worse!
 
The "flushing with a bleach mixture solution at the start of spring" is what took care of the rotten egg smell.
 
I got a return call from the manufacturer (Seaward) today. I had put a call in to them prior to initiating this thread. They were a little slow getting back with me, so I assumed I may not hear from them, thus I brought it up here.

Anyhow, I had asked a few questions, and here's the bottom line from Tom at Seaward:

I asked if I could run the engines without harming the heater if I had drained and bypassed it. I explained that I may end up doing this a little as I extend my season slightly with an Xtreme Bilge heater. Answer: No......BUT, the excess heat from an empty tank, and an active heat exchanger loop will almost always result in tripping of the thermal switch, and require removal of the electrical cover to reset. No harm, no foul. His suggestion if you were going to winterize water systems, but still run engines afterward......Bypass the water lines AND the Heat Exchanger Lines.

I asked if RV antifreeze would harm the water heater. Answer: No.

I asked if the water tank would be completely empty after utilizing the drain valve. Answer: No. He did say that more will come out if the T/P relief valve is cracked open momentarilly, which makes sense to me.

He also indicated that because the last little bit of liquid does not come out utilizing the drain valve, it is difficult to remove all anti-freeze come spring. This is why they recommmend bypassing both the water supply and discharge lines, as well as the heat exchanger lines. The latter again is to keep from tripping the thermal switch.

Hope this helps.......I know it did for me.

Thanks to all,

GW
 
Great info, thanks GW. If you're concerned at all about not getting the last of the water out, just leave the drain valve open all winter.
 
That last bit of water isn't going to be a problem. If it freezes it'll be expanding upward into a much larger space (the round part of the actual chamber). Water freezing inside closed areas is the problem. Inside of a hose or fitting it has nowhere to go, so the expansion breaks the surrounding materials. But if it's got somewhere to go it will, think of how the ice cubes in your home refrigerator end up sticking up a bit when you fill them the top.

Interesting suggestion on bypassing the heat exchanger lines. But if the water is moving then there really shouldn't be much risk to anything. If it was "that hot" it'd be a bigger problem for the hoses long before any metal suffered.
 
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