Safe to temporarily bypass a hot water heater and use engine?

[bsangs]

"Radiance" has a Yanmar 3GM30F engine that runs to a six-gallon Whale F600 hot water heater under the cockpit. Aside from winterizing the Whale, have never really paid much attention to it, since in the immortal words of Steve Jobs, "It just works." Well, it did just work anyway. Now it's leaking from the corner. Not sure if from old age, or me having screwed up the winterization.

Anyway, what it's leaking is engine coolant. Aft bilge compartment was pink and tasted sweet, which made NO sense to me, as I use blue non-tox antifreeze for winterizing. There was nothing dripping below the engine on the absorbent pads I keep in place. So kept going further aft and noticed pink dripping from the lower front right corner of the hot water tank. At this point I'll admit to being completely flummoxed, but after a deep dive into the engine/water heater relationship, I now understand their dynamic regarding the coolant loop.

Seems like a simple (Ha!) cut and paste replacement with the same Whale model, so am not really fretting the work. That leads to my question - until I replace the Whale, could I just couple the input and output hoses of the water tank to "complete the circuit," so to speak? I've read about people removing their hot water tanks and capping the engines, but that's more of a permanent solution. I'm just looking for something temporary that'll allow me to use the engine if I don't replace the tank promptly. However, I'm not at all sure if that's safe to try, so thought I'd see if anyone here has done it.

 

[Loren Beach]

The plumbing bits may need some thought, but they are not that numerous. As for the coolant 'loop' , remember that hot water heaters are/were optional on many boats and the engine coolant system is designed to work just fine without routing the coolant thru the coil in a hot water tank.
Matter of fact, when I was ordering up our new Betamarine diesel back in 2018, the connections for the remote hot water tank coil were optional.

 

[bsangs]

The plumbing bits may need some thought, but they are not that numerous. As for the coolant 'loop' , remember that hot water heaters are/were optional on many boats and the engine coolant system is designed to work just fine without routing the coolant thru the coil in a hot water tank.
Matter of fact, when I was ordering up our new Betamarine diesel back in 2018, the connections for the remote hot water tank coil were optional.

Thanks Loren. I realize the hot water heater can be taken out of the equation for the engine to work, I just want to make sure I do the new equation properly. I don't know if it's as simple as coupling the engine coolant intake and output lines together during the tank's downtime. Theoretically it should be, but being unsure of potential PSI issues, etc., I want to be sure. Certainly don't want to do something that's going to potentially harm my engine.

 

[Nick J]

with the different coolant collars, it sounds like you have another heat exchanger somewhere in the system. That should make bypassing the hot water heater easier. Any work you do shouldn't affect the engine coolant system. Do you have any pics of your engine compartment?

 

[bsangs]

with the different coolant collars, it sounds like you have another heat exchanger somewhere in the system. That should make bypassing the hot water heater easier. Any work you do shouldn't affect the engine coolant system. Do you have any pics of your engine compartment?

Nothing of recent vintage, unfortunately. Just a few of the tank itself. Next time I'm over will take some fresh pics.

 

[Dave G.]

Just disconnect the "in and "out" hoses and join them together with a fitting and clamps from the hardware. I would get a straight and a 90 degree fitting in hand before you pull the hoses. You also may have to release a hose bracket or 2 to get enough slack to join them together. Probably 3/4" hose but double check to be sure. You either have to move fast or pinch/clamp the hoses before you disconnect and make sure there is no pressure in the system(cold). Have a bucket handy to catch spillage

 

[Prairie Schooner]

"Radiance" has a Yanmar 3GM30F engine that runs to a six-gallon Whale F600 hot water heater under the cockpit. Aside from winterizing the Whale, have never really paid much attention to it, since in the immortal words of Steve Jobs, "It just works." Well, it did just work anyway. Now it's leaking from the corner. Not sure if from old age, or me having screwed up the winterization.
. . .

Brian, this is making me question my own winterization process. I clear all three tanks then run -100º antifreeze through it all until the stream coming out is full color. (My theory on the extra cold AF is that it will inevitably get diluted.) I haven't been doing a separate drain of the water heater. In the spring I can save 2-4 gallons of what I clear out to start the process the following winter. I estimate that each year the system gets 75% new AF.
How have you been doing it?

 

[bsangs]

Brian, this is making me question my own winterization process. I clear all three tanks then run -100º antifreeze through it all until the stream coming out is full color. (My theory on the extra cold AF is that it will inevitably get diluted.) I haven't been doing a separate drain of the water heater. In the spring I can save 2-4 gallons of what I clear out to start the process the following winter. I estimate that each year the system gets 75% new AF.
How have you been doing it?

That's the same way I do it Jeff, including using the -100 non-tox antifreeze. This is engine coolant leaking from the hot water tank though, not the antifreeze. (Now, maybe there is some antifreeze mixing in with the engine coolant, but red/pink is definitely the dominant color.) I don't know what happened. I'm leaning toward old age of the tank though. It was already on board when the previous owner purchased her in 2010. I already have the new tank and am installing it this week or next, so my original query isn't even going to come into play.

 

[Dave G.]

This is engine coolant leaking from the hot water tank though

There is a heat exchanger in the HW tank to heat the water from engine temp. It has failed allowing engine coolant to leak into the system.

 

[JJCiolino]

If you think about, with the hot water tank empty of water, there is nothing to freeze and burst. The engine antifreeze doesn’t freeze as designed, so you know that didn’t cause a burst of that side of the system. So this tells me you are winterizing correctly but the system is just old. Mine is too and doesn’t work.

As for the bypass, just connect the two hoses together. It’s that simple. And as already stated, have a bucket ready.

 

[Prairie Schooner]

That's the same way I do it Jeff, including using the -100 non-tox antifreeze. This is engine coolant leaking from the hot water tank though, not the antifreeze. (Now, maybe there is some antifreeze mixing in with the engine coolant, but red/pink is definitely the dominant color.) I don't know what happened. I'm leaning toward old age of the tank though. It was already on board when the previous owner purchased her in 2010. I already have the new tank and am installing it this week or next, so my original query isn't even going to come into play.

Your reasoning seems sound to me. Do you think the Whale was the original? I wonder how long a water heater should last.


Our 'new' water heater was installed by the PO in 2008, IIRC. I've got the receipt, somewhere.
After a 2 month hiatus I'm taking back up on the revamp of our cooling/exhaust system.

Coolant Conundrum

We've got oddly fluctuating coolant levels and composition and I can't figure out what's going on. The coolant level will be quite low sometimes. The only time the level drops is when the engine runs, but it isn't uniform. Sometimes the level will be fine even after running for 30-60 minutes. I...

ericsonyachts.org

Currently I'm cobbling together a device so I can test the pressure holding on the water heater circuits. I'll post on that when I have more definitive progress.

I'm pulling for you, Brian. We're all in this together.
J

 

[Prairie Schooner]

If you think about, with the hot water tank empty of water, there is nothing to freeze and burst. The engine antifreeze doesn’t freeze as designed, so you know that didn’t cause a burst of that side of the system. So this tells me you are winterizing correctly but the system is just old. Mine is too and doesn’t work.

As for the bypass, just connect the two hoses together. It’s that simple. And as already stated, have a bucket ready.

Hi JJ,

I'm not draining the water heater, just swapping anti-freeze for water. If I don't do it right/well, there could be water (or a light mix) trapped in the water heater. I've avoided just draining the WH because it seemed so cramped back in there. But I'm getting real familiar with that area and may drain it in following years.

If you're in Riverside, we're practically neighbors. We winter at Borden Light and spend summers on a mooring in Dutch Harbor. Many moons ago I had an apartment down on the Terrace.

Cheers,
Jeff

 

[JJCiolino]

Hi JJ,

I'm not draining the water heater, just swapping anti-freeze for water. If I don't do it right/well, there could be water (or a light mix) trapped in the water heater. I've avoided just draining the WH because it seemed so cramped back in there. But I'm getting real familiar with that area and may drain it in following years.

If you're in Riverside, we're practically neighbors. We winter at Borden Light and spend summers on a mooring in Dutch Harbor. Many moons ago I had an apartment down on the Terrace.

Cheers,
Jeff

Jeff, very cool. I actually own Bullock Cove Marine on the terrace.
I bought my 28+ from one of my customers. Only got to sail it a few times last year but I can’t wait for this summer. The water heater for me is on the list. This year I painted the mast and am putting all new standing and running rigging on.
It’s kind of a busman’s holiday but I really enjoy working on the boat.
Jim