Hot water heater

[rickasbury]

Ok, back in the water. Someone else suggested with the boat running and the pump switch off, if the water comes out than the heater core is bad...but that would say that it is hot water coming off the heat exchanger circulating in the heater and not coolant. These heaters are not cheap! Would you all concur?

 

[kd4pbs]

Turn off the pump, then open a hot tap. Let all the pressure bleed off, then close the tap. Start the engine and run around a while, heating all the water in the tank - probably 20-30 minutes or so. With engine running, open a hot tap. I would imagine a small amount of water will come out due to the expansion of the water. If lots come out and continues to flow, then you've got a bad water heater with a hole in the heat exchanger portion.
Yeah, those water heaters are not cheap for sure.
Another way to find out would be to bypass the coolant loop in/out, pressurize the fresh water side, and see if water flows out of the open coolant loop of the water heater.

 

[muc]

It's been over a decade since I winterized a water heater. But it looks like the check valve is screwed into the hot outlet, should be in the cold inlet. Take a close look below where those hoses go into the heater. Should be a C and H stamped below them. If someone got things mixed up you can get hot water at a cold faucet, but only for short time, it will turn cold in a minute.

 

[rickasbury]

Ok- think this one got figured out. There must be a small leak in the heat exchanger inside the water heater which is pressurizing the system with really hot water- so the water will run, super hot without the pump being turned on. From what I read is not serviceable- but what i read today, the electric side should still work. I would pull the lines from the engine and loop those together. The unit will then work on electric on shore power or genset...that sound right?

 

[Grub54891]

Ok- think this one got figured out. There must be a small leak in the heat exchanger inside the water heater which is pressurizing the system with really hot water- so the water will run, super hot without the pump being turned on. From what I read is not serviceable- but what i read today, the electric side should still work. I would pull the lines from the engine and loop those together. The unit will then work on electric on shore power or genset...that sound right?

The heat exchanger will still leak out so it will empty the water tank. Unless you cap the hoses or plug them.

 

[rickasbury]

The heat exchanger will still leak out so it will empty the water tank. Unless you cap the hoses or plug them.

10 4, that's what I was thinking...

 

[Comogene]

Something does not make sense. The closed loop engine system circulates coolant. The water heater is tapped into that system. If there is a leak in the water heater's internal heat exchanger, it would be coolant from the loop into the fresh water system inside the water heater. You would be loosing coolant in the engine system and that coolant will come out through a fresh water faucet. If it is just hot fresh water, you do not have a leak in the loop system. It is simply a backfeeding of hot water from the heater into the cold water side. If you run that faucet, the hot water should dissipate rather quickly and be followed by cold water. This is why many systems put a check valve in the cold water feed side to the heater in order to prevent the back flow when the pump is off. If you have a check valve on the cold water side - it is stuck open.

 

[Comogene]

Another issue: it does not appear that the "winterizing" system is properly plumbed, if in fact it is utilized for winterizing. You need a second diverter valve on the hot water side of the "T" to prevent the antifreeze from flowing back into the heater. The process would be to close both valves, thus routing the anti-freeze through the cross-over piping and not through the heater. Open the faucet at the bottom of the heater and open the pressure relief valve to drain the heater. In the Spring, flush fresh water through the system, open the two valves (which will close off the cross-over) to fill the heater and turn it on.

 

[rickasbury]

Another issue: it does not appear that the "winterizing" system is properly plumbed, if in fact it is utilized for winterizing. You need a second diverter valve on the hot water side of the "T" to prevent the antifreeze from flowing back into the heater. The process would be to close both valves, thus routing the anti-freeze through the cross-over piping and not through the heater. Open the faucet at the bottom of the heater and open the pressure relief valve to drain the heater. In the Spring, flush fresh water through the system, open the two valves (which will close off the cross-over) to fill the heater and turn it on.

Good morning!
I'm reviewing your comments, thank you for posting your thoughts.
The boat is a florida boat so perhaps it was not set up for winter? The boat had 50 hours on it when I bought it. It did come down from the panhandle which can get pretty darn cold- maybe someone has messed with it but everything has worked for like 10 years.

 

[rickasbury]

Something does not make sense. The closed loop engine system circulates coolant. The water heater is tapped into that system. If there is a leak in the water heater's internal heat exchanger, it would be coolant from the loop into the fresh water system inside the water heater. You would be loosing coolant in the engine system and that coolant will come out through a fresh water faucet. If it is just hot fresh water, you do not have a leak in the loop system. It is simply a backfeeding of hot water from the heater into the cold water side. If you run that faucet, the hot water should dissipate rather quickly and be followed by cold water. This is why many systems put a check valve in the cold water feed side to the heater in order to prevent the back flow when the pump is off. If you have a check valve on the cold water side - it is stuck open.

Intersting thoughts- if it indeed is leaking coolant into the water system it's not real apparent. Can't really go by the reservoir, unless it was just empty. I popped the engine heat exchanger and it was pressurized and full - so I'm suspicious of diagnostics but don't have another explanation. A new heater is about 600 bucks.
I believe the primary reason that everyone has leaned to this is the fact the system pressurized with the engine only running and up to temp. The hot water does not stop coming. I've had the boat for 10 years and has never been as issue.
So if you operate any of the faucets engine running (but before the thermostat opens?) It'll operates fine but it seems once the engine gets to temp the fun begins. And is super hot. I guess i got to the point of whether it is a heat exchanger failure or not, it must be something else internal? I'm certainly open for anything to try- the only thing that happened just prior to the issue is I replaced the water system pump- but was totally plug and play. I can't imagine any connection there? Is there something I'm missing there? It all seem to happen at about the same time. I don't recall if I ran the boat with the repair without issue as sometimes I have big gaps of usage...

 

[Grub54891]

I think if you do the bypass of the hoses would be a good test of what’s going on. If it doesn’t get hot when bypassed you narrowed it down to an issue with a check valve or heating coil. You could pressurize the hoses separately from the system and see if it leaks down.