Replacing Seaward Hot Water Tank

[Brian B]

Has anyone replaced a Seaward Hot Water tank model S-600 on a 25 or 27? Looking for any tips or tricks for removal and installation. On my 25SC access to the rear hoses would be through the hole under the head sink. I can reach them however if there is a mounting bracket on the rear of the tank that is screwed to the deck this would be behind the shower sump pump box making access to any mounting screws more of a challenge. I need to repalce the tank as I have found engine anti-freeze leaking from the tank itself, not the hose connections.

 

[captstu]

I replaced the shower sump with a small in-line pump on my R 25. It works much better than the original showers sump and give me easy access to the hot water tank.

 

[dclagett]

Brian,

I have the same problem with my RT25SC. This past season I turned off the coolant lines to the tank and kept boating. Over the winter I plan to remove the screws that I can access to see if the tank will move. I hope there is sufficient slack hose so I can slide the tank into the cockpit storage area without removing the coolant lines through the head storage compartment. I am not sure when I will get to this but will let you know what I find.

I am getting somewhat frustrated with the numbers of failures I am having with a 4 year old boat. My helm pump also went up this year leaking fluid. What is next?

 

[captstu]

The hoses are very short. Cut and splice onlt

 

[Brian B]

I jumped into this project today after I made my initial post. I figured I would start with the hardest part first, disconnect the engine feed hoses, their length will not allow the unit to slide out. They are accessed through the hole that is under the head sink. The hoses are up high on the water tank so they are not blocked by the shower sump box. Mostly by feel I loosened the clamps then gave the hose a twist with a pair of pliers, reached in with my hand and pulled and twisted the hoses off. I capped off the hose ends with a wood plug I made from a dowel before hand (Mike Rizzo's idea). ( I thought the hardest part was done, wrong.) Now working in the lazarette I disconnected the water lines, electric feed cable and two screws that hold the mounting bracket to the decking. There is a rear mounting bracket on the head side, this is not screwed in, it slides into a cut out on a piece of starboard that is screwed down. The unit can now be slid forward and out (so I thought). I had to remove the fresh water pump for more room, if there is an inverter in this space that may have to be removed also. Now I tried to remove the unit from the lazarette opening, no joy. The unit has to be tilted and the top starboard side of the unit catches on the underside of the water drain gutter, it needed about a 1/4" to clear it. I made another call to Mike Rizzo who suggested trying to disassemble the unit. There are 16 screws that hold the cover on. Using an offset phillips screwdriver I was able to remove the screws in about an hour, working space is extremely tight and I could only get about 1/2 turn at a time. With the screws removed the cover slid off, the front and back panels flexed and I was able to lift it out of the lazarette opening. The tank is wrapped in insulation and the bottom of the insulation was soaked with engine anti-freeze. Now to purchase a new tank and will most likely have to disassemble that one to get it into the lazarette.
Hope this helps anyone that has to tackle this job with a few less expletives. Working in 33 degree weather didn't help any.

 

[captstu]

A 3 gallon replacement may fit better and still produce enough hot water for your needs. I take it your engine coolant was leaking?


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[Brian B]

A 3 gallon replacement may fit better and still produce enough hot water for your needs. I take it your engine coolant was leaking?


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

Yes the engine coolant was leaking from the water tank. I have ordered an exact replacement from Defender Marine, I don't think a 3 gal would be sufficient.

 

[captstu]

I have had a 3and a 6. If you use the engine to make hot water, the heater functions as. An ‘instant’, making all you want faster than you want it.

I use a tempering valve to mix cold and hot so the shower gets 120 degree water. During the valve installation, I used the whole 25 gallons of fresh water and never fell below 120 degrees.

With electric only 6 gallons has some merit.

How did you find the coolant leak?


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[Brian B]

I have had a 3and a 6. If you use the engine to make hot water, the heater functions as. An ‘instant’, making all you want faster than you want it.

I use a tempering valve to mix cold and hot so the shower gets 120 degree water. During the valve installation, I used the whole 25 gallons of fresh water and never fell below 120 degrees.

With electric only 6 gallons has some merit.

How did you find the coolant leak?


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

There was a trail of engine coolant coming from the left front corner of the hot water unit. The hose connections were dry so it had to be an internal leak of the tank. I also have a mixing valve installed, I got the idea from you a couple of years ago in FL.

 

[captstu]

Thank you. I’m slowly losing engine coolant, 1 coolant cup every 4 hours at 3400 rpm, and can’t find the leak. I’ll look at my hot water heater again.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[Brian B]

Thank you. I’m slowly losing engine coolant, 1 coolant cup every 4 hours at 3400 rpm, and can’t find the leak. I’ll look at my hot water heater again.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

Stuart,

The tank has a blanket of insulation covering it. On mine the bottom of the insulation was saturated with coolant. Perhaps depending on the size of the leak the insulation could be absorbing it and not show on the outside of the unit.

 

[dclagett]

Brian,

Thanks for sharing how to remove the hot water tank. I may or may not get to it this winter since it is not a priority. The hot water works with electric and we never use the cabin heater. If we need either this gives us a reason to run the generator which needs to be run more.

Have you thought about going to a different manufacture? I have had several boats with these types of hot water heaters and never had a problem. Before I replace mine I will try and understand what is available that may be more reliable. Also there are hot water heaters out there that have all connections on one end. You would need to extend the coolant lines, but this would help with removable and installation.

Good luck in your repair.

 

[Brian B]

Brian,

Thanks for sharing how to remove the hot water tank. I may or may not get to it this winter since it is not a priority. The hot water works with electric and we never use the cabin heater. If we need either this gives us a reason to run the generator which needs to be run more.

Have you thought about going to a different manufacture? I have had several boats with these types of hot water heaters and never had a problem. Before I replace mine I will try and understand what is available that may be more reliable. Also there are hot water heaters out there that have all connections on one end. You would need to extend the coolant lines, but this would help with removable and installation.

Good luck in your repair.

I did look at the Isotemp, they are round, 6" longer, S.S. tank and about twice as much money. The Seaward is also available with the all the connections on one end . I decided to go with the original set up. Re-installing the hoses on the back of the tank won't be too bad. Extending the hoses to the front would require more connections with 90 degree elbows thus more chances of leaks. The new tank should be delivered today, I need to get it finished as I plan to trailer the boat to FL in 3 weeks. The Seaward tank is $325.00 + shipping from Defender.

 

[Brian B]

Update: Installed the new tank in reverse order of the removal by removing the cover, placing the cover in the forward part of the lazarette, placing the unit in the lazarette, sliding the cover on and installing the cover screws, only the screws I could reach easily. I completely disassembled the old one, I was mistaken in stating that it leaked engine coolant, it is actually RV antifreeze. The design of the tank is that the engine loop is inside the tank, if the engine loop was to leak I do not think it would show on the outside of the tank. I tested the tank with air and I also let it sit for two days full of water, I could not find a leak. So the question is where did this RV antifreeze come from? My only conclusion is that when the shower sump was being winterized the pump did not operate, (float switch needed to be replaced) the sump box would have overflowed spilling antifreeze near the tank assembly and the insulation acted as a sponge.
My curiosity got the better of me and I called Seaward. The company was sold to Attwood 3 years ago and the tanks are now being produced in MI. The person I spoke with stated the engine loop is a double lined loop, both loops would have to corrode for coolant to enter the the domestic water and the smell of engine coolant would be noticeable at the faucet. Average life of the units are 10 years.

 

[YukonRon]

Brian, thanks for the info and especially the update. How to access that tank if (when) it becomes necessary has been a worry in the back of my mind. Especially with winterizing here at temps down to -30C. This year I bypassed, drained, and blew it out so I will sleep better. Your writeup will definitely go in my service notes for future reference. Great info to have. 😀

 

[captstu]

I've been hunting for a very slight coolant leak o my R-25 for about 18 months (under a gallon leaked in that time). I suspected the hot water heat exchanger - so I got into the habit of leaving the pressure water on at all times - thus, I'm guessing, if there were a leak it would be into the coolant loop - and the fresh water pump woud cycle occasionally.

I don't think the fresh water pump cycles at all - after I replaced a number of failed original hose clamps in the fresh water circuit.

I'm guessing the leak is elsewhere - and is so small I'll probably never find it.

When I first start up, coolant goes into the overflow tank because I overfill the heat exchanger slightly - just a cup or so. This leaves the expansion bottle overfilled, but none of this ever seems to go back into the engine. This might indicate local boiling in the coolant loop or a pressure leak from the engine head or exhaust manifold into the coolant loop - I don't know how to find either of these.

But, I don't think it is possible for coolant to be leaking into my domestic hot water - the smell and taste are very distinctive and my water seems fine.

In the meantime, I'm replacing the raw water intake system - more with photos when the boat is back in the water.

 

[knotflying]

Stu,

If you suspect you have a leak from your Antifreeze coil in the water heater I would leave my domestic water pump on and also leave the cap off of the heat exchanger. I know it is difficult to get to, but try that. I suspect that the pressure of the cap may be too large for the domestic water pump to overcome and push the extra fluid to your overflow tank. If you have overflow the following day then that would confirm a leak.

 

[captstu]

Mike, great idea.

Since the cap on my heat exchanger is so hard to reach, I have purchased and am installing a pressurized coolant recovery tank to replace the factory open tank.

I plan to remove the inner ring from the heat exchanger cap so I can more easily check and refill the coolant loop.

At that point, I’ll. Measure the coolant level in the new tank and run the test you suggest.

Good idea, thank you.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[griervictoria]

I have had a small amount of coolant leaking on my 2014 R31, for a few months. It has now been diagnosed by pressure testing as a leak in the hot water tank from the coolant which works the bus heater and heats the water from the engine.
The bad news is that to replace the 5 year old tank requires the stove to be removed as well as some cabinetry and a new unit fitted. The estimate for this is $2450 US, including parts and labor, which is staggering to me and so for the moment, I am going to check my coolant level every trip out of the boathouse and keep adding as required. It leaks about a cup every 4 or 5 hours.
I am surprised that after 5 years a hot water tank which in a boat is not used nearly as much as a domestic hot water tank should fail.
Has anyone else had this experience?

 

[dclagett]

Sorry to hear about your coolant leak problem. Are you sure it is not a host connection? I have the very same problem in my 2014 RT25SC and I just turned off the coolant going to the tank. We use hot water when cruising, however we have a generator so we just turn on the electric heater. If we need cabin heat we run the reverse cycle A/C or a small space heater.