Kuuma water heater leak

[seabum]

My new this spring 11 gallon Kuuma water heater has sprung a leak. Purchased from from Defender and installed this March.
I have been fighting with fresh water connections as I talked to the Kuuma people and they feel the leak is likely in the hose connections.
Have redone all connections with industrial pipe dope and heavy duty teflon tape; fitting and hoses are all dry and still have a leak. Has to be a split weld in the tank.
My water pump cycles about every 15 minutes. When I rotate the heater bypass valves to isolate the heater the pump no longer cycles.
Kuuma says remove the heater and drill out the pop rivets to inspect the tank and if is split they will send a replacement. This is a real pain and I think I am done with Kuuma and their five month old heater,. Plan to move up in quality.
Anyone else our there have a Kuuma problem? What brands are people happy with in their boats?
Headed off to defenders today to see what they say.

 

[sunchaser]

Isn't Kuuma an aluminum tank? Al water heater tanks can indeed fail early, but in just a few months sounds like build quality. Riveted construction? Suggest a glass lined tank if you replace, such as Torrid.

 

[drb1025]

I installed a Torrid last fall after my Seaward leaked. Torrid has a very good reputation and the are local for me, built on Bainbridge Island, WA.

 

[BeeJay]

I suspect that you’ve ruled this out, but if there is no sign of a leak except that the pump cycles excessively when the water heater is bought online. Could it be that as the water heats and expands it triggers the relief valve to open and then the pressure in the tank drops below the set point of the pump, causing the pump to restore the pressure, repeating the cycle until your water runs out. If these are the symptoms and the relief valve came with the new water heater it would be worth eliminating first if you haven’t already.

 

[seabum]

I suspect that you’ve ruled this out, but if there is no sign of a leak except that the pump cycles excessively when the water heater is bought online. Could it be that as the water heats and expands it triggers the relief valve to open and then the pressure in the tank drops below the set point of the pump, causing the pump to restore the pressure, repeating the cycle until your water runs out. If these are the symptoms and the relief valve came with the new water heater it would be worth eliminating first if you haven’t already.

Every pipe fitting and the relief valve have been wrapped with paper towels and clipped in place for a completely day and ALL fittings are dry.
Pump cycles about every 12 minutes, and when the water heater bypass loop is used the pump does not cycle. Water collects around the base of the heater.
Leaking tank is the only possibility as far as I can tell.

 

[Pau Hana]

Another vote for Torrid- great water heater. They even delivered it to our boat- they wanted our old 1994 30 gallon Torrid water heater to tear down and examine.

 

[DavidM]

Another way to test your heater for leaks is a pressure test. Block off the discharge (hot water side) and hook a valve and a gauge to the inlet (cold water side). Turn on the water pump and bleed the outlet until no bubbles. Then close the inlet valve and watch the pressure. Should hold steady for 15 minutes.


David

 

[AusCan]

They are a budget water heater, although I've yet to have any issues with my 2 year old Kuuma. I'll be happy if I can get 5 years out of it as it it less than half the price of a top quality heater.

If you are going to pull it out, you may as well spend 5 minutes checking to see if it's split and get a new one under warranty.

 

[John mohr]

I am a little late joining Trawler forum. I googled Kuuma water heater problems and this thread popped up. I have had the same leak issue twice. The first time I pulled my hair out trying to find the source of the fresh water in the hull. It only showed up during running when the stbd engine coolant heats the water hotter than the 220 element. Nothing leaked in port on shore water or water pump pressure. It finally got worse to where it was visible at the base of the heater all the time and I found out where it was coming from. The lower weld seam had a hair line crack. This heater was new from boat manufacture. It was 9 years old when the leak started. I ordered a new one from Defender. It lasted 3 years until the same leak occurred. I knew exactly where it came from this time. I thought about taking the jacket off and welding the crack then reinforcing it with aluminum angle welded over the bottom seams. On second thought, I am looking for a different brand. Aluminum just work hardens and gets brittle. The weld might not work well with any calcium or mineral build up on the inside causing a dirty weld even if I purge it with argon during welding.
Anyway, that’s my frustrating experience with Kuuma.

 

[Puffin_NT32]

The factory installed original Seaward 6 gallon h/w tank started to leak after one year. Leaked around weld at hose connector from heat exchanger. Under warranty, factory sent me another Seaward tank. Six years later, tank started to leak at another connector, and I replaced it with a "plug-compatible" Kuuma tank from Defender, $260. This third tank lasted 10 years (May 2023) before another leak developed. Pulled aluminum cover off and leak was at a tank welding seam. Replaced with another Kuuma ($335 Hodges Marine). With PEX pipe and tank bypass connections, a more expensive stainless tank will require plumbing and connection changes. A stainless tank is 2 - 3 times more expensive. With my current access and connections, I can replace a Kuuma-style tank in about an hour. My position is that these aluminum tanks will develop weld seam leaks, and I treat them as a maintenance item, needing periodic replacements. We spend a lot of time on the hook, and if I had a generator onboard, I might be tempted to install a small on-demand 110 volt water heater. I installed one under my kitchen sink at home, and they work just fine.

 

[Mischief Managed]

If and when you do replace a water heater, I recommend that you install an anti-scald valve in the boat plumbing and connect all the plumbing to the water heater with silicone heater hose and garden hose connectors (just like a washing machine). Make the hoses extra long so that a future water heater swap with be super easy. The garden hose connectors also make draining and by-passing the heater really easy for Winterization.