Hot Water Heater Replacement

[Bob R.]

Finally confirmed that my Seaward water heater was leaking and the cause of aft cabin sole damage. I wasn't sure if the source of the leak was a leaking port frame in the aft cabin or the water heater. Both the inside surface of the hull and the water heater locker drain the the front of the heater locker where the aft cabin sole joint is exposed. The water has done a lot of damage in a relatively short period of time.

I ordered a new Seaward S600 from Defender Sunday night and it was delivered this morning. Local WM said it would take 3 weeks to special order and wanted $70 more??

Question: I presume I am going to have to drain the engine closed loop cooling water to remove and reattach the hoses to the water heater heat exchanger. If I am going to have to drain the cooling water I might as well flush the cooling system and put in fresh antifreeze. How do I flush the system and prevent the old cooling water and antifreeze from spilling into the bilge and getting pumped overboard?

 

[woodster]

you might use a wet/vac... first open the rad cap and vaccum out all that you can from there and then un hook the top hose and vac out the rest or get a bucket and drain it all in there....(be careful and dont drink that stuff because it tastes very funny)lol

regards

woody

 

[Alan]

Plug the two hoses when you remove them from the heater. Remove the heater and run fresh water through one hose and collect the coolant as it exits the other. When clear water runs through you can stop the flush. Blow the entire system out with compressed air to empty the entire system. When you reattach the new heater fill the entire system with global (yellow) anti freeze.

 

[Ross]

How come nobody ever installs a cold water heater?. If I have hot water I don't need a heater. lol

 

[Steve Dion]

Bob:

If you have green antifreeze and decide to change to Dexcool, be sure that ALL of the old stuff is out of the system. I am not sure that this will happen with the thermostat in place. I have not done this, I had it done.

There may be some trick to be sure that all of the old stuff is gone before you refill the system. You will also need to be sure that there are no air pockets in the lines.

 

[Bob R.]

As always, thanks to everyone for your advice. I hope to get this done on Saturday so I can going sailing on Sunday! I have a few follow-up questions:

Alan, you suggested refilling the system with "global (yellow) anti freeze". I think the stuff tht is in there now is red, left over from the previous owner. Is global a brand name product?

Stu, I noticed that you removed your response. I was reading the post you had on the link you included. I printed the instructions on burping the system after refilling to use as a reference. You suggested using distilled water with the antifreeze. Is there a problem using tap water in the fresh water system?

Steve, you refered to Dexcool antifreeze. Is it better for use in marine diesel engines? Do I need to add a corrosion inhibitor in addition to the antifreeze?

 

[Steve Dion]

It is the recommended coolant from Yanmar these days. There was some talk about issues with it in the past, but I am sure that Yanmar would not be recommending it if they thought these issues were valid on their engines.

Check with your local Yanmar dealer/distributor and see what they have to say about it.

PS: I have been running it in our engine for the past 3 years. We also have several other Yanmar users that have switched to it too.

 

[Ron20324]

At (WalMart?) I noticed the price of Texaco AF at full strength, and the same stuff "pre-mixed" to half/half. You'd think the pre-mix would cost half as much? It's the new math, methinks.

Bob, tap water has chemicals and nasty stuff that can build up over time and maybe cause blockages. Distilled is pure, clean, water.

 

[BarryL]

Hello,

You don't HAVE to drain the old coolant. Just be ready with some plugs. Remove the line and insert the plug. You will have very little spillage. Of course, changing the coolant every few years is a good idea.

Note that bleeding all the air out of the coolant lines can be difficult. It took me 2-3 heat / cool cycles to get all the air out.

Good luck,
Barry

 

[timvg]

We recently replaced our 1993 Seaward hot water heater with a new one. I plugged the hoses that go into the water heater's heat exchanger and didn't have any problem with air in my cooling system after installing the new hot water heater. Also make sure that you also plug up the hose connectors on the old hot water heater or else you'll have coolant running all over the place. I used thru-hull plugs, which worked very well.

 

[Zaphro]

I had to replace mine a few years ago, used a wet-dry vac to clear the old coolant, but you've already got that advice. I would recommend you install a bypass valve to prevent the need of worrying about this in the future. It will allow you to isolate/bypass the water heater.

 

[Alan]

Dexcool is a disaster. Do not use it in anything. It clogs and corrodes heat exchangers, hoses and just about everything else. Global long life anti freeze is excellent for extended use and is compatible with everything. All anti freeze lowers its ph over time and needs to be replaced regularly. If a vacuum extractor is used to remove the old stuff bleeding will not be needed when replacing. If you don't have access to one just flush with fresh water.

 

[Steve Dion]

Alan:

There has got to more to it than just the Dexcool. This stuff is used in millions of vehicles. I realize that there were issues many years ago, but I would be really suprised if these issues still persist. Yanmar deliveres all of their new engines with this as the recommended anti-freeze. I am using the Shell version of the stuff in out engine. We have not had a single issue with the product.

 

[kloudie1]

Uhhhh My Humble (before it was Exxon) opinion is that the new stuff is there because of pressure by GovMint to go toward non-toxics .. not because it actually is best for use in an engine.. My personal experience is that 1, it has long life, but 2, when its life is over, it produces a clogging agent which will clog a radiator such that it cannot be reasonably cleaned and has to be replaced.. It also has to be flushed out of the engine by roughly 4 hours of high pressure reverse flush.. I am now, once again, perfectly happy with the old green stuff! When its life is over(easy to check), it doesn’t protect against freezing, but it also doesn’t ruin a radiator. The “new” stuff is now flushed out of the boat and the other car.. before it had a chance to ruin more heat exchangers. (your experience may vary.. offer void where prohibited by law.. opinions stated are those of this guy and not necessairly those of the management)

 

[Alan]

Steve, I have seen hundreds of cooling systems ruined by Dexcool. I have no idea how or why manufacturers make their corporate decisions (and public good has nothing to do with it) but I can tell you that this stuff is very bad news for all engines and would recommend everyone who has this stuff in their cooling systems get rid of it ASAP. Global anti freeze is the best alternative currently. A word to the wise....