Heating Fresh Water

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AMCarter3
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Heating Fresh Water

Postby AMCarter3 » Wed Mar 22, 2017 10:46 pm

I'm confused about how fresh water (for the galley and head) is heated on our boat. We are about to replace our hot water tank (located behind the Port engine). My maintenance pro says the water in the hot water tank is ONLY heated when the electrical breaker for the Hot Water Tank is turned ON. I said that's NOT my understanding of what the original owner's manual says... it says:

4.6 WATER HEATER
Water is heated by a heat exchanger that draws hot water from the cooling system of the port engine when it's running and stored in a six-gallon tank. Alternatively, 115 VOLT AC electrical power from the generator set or shore power, as available, also provides heat. A thermostat controls the maximum temperature. After periods of disuse, the tank should be flushed with fresh water.
CAUTION: lf there is no AC available from shore or from the generator and the inverter is switched ON, the batteries may be discharged quickly.


My maint. pro says, "He says there is no heat exchanger on the Port engine and there are no hoses leading into the Hot Water Tank from the Port engine." Yet, my interpretation of the original manual's description means heat from the Port engine is transferred through a heat exchanger to heat FRESH water that is stored in the 6-Gal hot water tank. AND, in addition, water in the hot water tank can also be heated when connected to shore power or a genset when the Inverter is turned ON. Am I right or wrong? Is there a heat exchanger the converts heat from the Port engine into hot fresh water that is stored in the hot water tank?

And if fresh water IS heated by the Port engine, how does this happen? Where is the heat exchanger?
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98
Bellingham WA

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Re: Heating Fresh Water

Postby deising » Thu Mar 23, 2017 5:48 am

Well, Mac, I can assure you that on our 2006 model, hull 91, we get plenty of hot water from just running the port engine - no electricity required. I am embarrassed to say that I cannot recall from memory exactly how the plumbing is routed to direct the hot engine coolant into the water heater.

Our heater is a Force 10, model 40603. An Internet search for the manual will give you illustrations showing the fresh water in/out and the the engine coolant in/out.

Now, it is possible that on your engine, some previous owner disconnected that plumbing. Please let us know what you finally discover.
Duane Ising
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Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade

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Re: Heating Fresh Water

Postby duetto » Thu Mar 23, 2017 8:17 am

the water tank heater plumbing runs from the fw pump along the hull side just under the deck joint. it then terminates on a pipe entering the water heater. this pipe runs around inside the tank and thus heats the drinking water by transfer. the engine water pipe exits the heater and then connects to another hose which returns to the engine fw pump. if you have a force 10 heater i believe it is capable of using engine heat to heat fw/drinking water.
john & diane cummings
duetto mv34 #23

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Re: Heating Fresh Water

Postby AMCarter3 » Thu Mar 23, 2017 12:16 pm

Thanks a lot, guys! Very helpful. I've passed this info along to our maint. guy. I also gave him the text from the original PDQ Owner's boat manual and verified to him that we definitely somehow get hot water when the Port engine runs. We're just not clear on the plumbing yet. We'll figure this out. I just want to be sure that the new water tank is plumbed like the old tank.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98
Bellingham WA

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Re: Heating Fresh Water

Postby AMCarter3 » Thu Mar 23, 2017 12:21 pm

I found the user manual for the Force 10, model 40603 water tank and passed it along to our maint. pro.
Thanks again!
Mac Carter
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Bellingham WA

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Re: Heating Fresh Water

Postby deising » Mon Dec 04, 2017 9:55 am

So, Mac, what was the final conclusion?

I just re-read these posts and saw that your maintenance guy was not able to find a heat exchanger. The rectangular object next to the valve cover on the side of the exhaust is the engine's heat exchanger, but all that matters to get hot fresh water from the engine coolant is for the hot coolant (about 175F) to be piped to the water heater. Internally, there is a heat exchanger that heats the fresh water and stores it in the 6 gallon tank.

Inside the tank is also the electric heating element that works when you have A/C power available (either from shore or the generator).
Duane Ising
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade

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Re: Heating Fresh Water

Postby AMCarter3 » Mon Dec 04, 2017 12:19 pm

This did get resolved. I took pictures of the heat exchange hose loop between the engine and the hot water tank and sent them to our maint. guy. He installed the new water tank without any issues. It was nice to help him sort our his "confusion". Thanks for thinking about it.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98
Bellingham WA

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Re: Heating Fresh Water

Postby James Power » Mon Dec 04, 2017 10:54 pm

Might want to look for another maintenance " pro ".
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Re: Heating Fresh Water

Postby Expatriate » Tue Aug 14, 2018 5:00 am

My water heater flips the breaker when I turn it on. It does not just flip the water heater breaker, it shuts down the entire AC electrical panel. This seems odd as it was working most of the season in the Bahamas. I have not touched the AC electrical system at all, but I have made a few simple DC mods. My inverter died and I am in the process of replacing it, but I am putting the new one in the same place as the old one with the same wires. It appears that the water heater has shorted. Anyone have their water heater do this?

Tim
M/V 068

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Re: Heating Fresh Water

Postby Expatriate » Thu Oct 25, 2018 8:52 am

So, my solution to the water heater problem started with disconnecting the water heater. When I turned on the breaker it did not flip. This told me there was no short in the wire, it was in the water heater. My experience with water heaters has always been the same, they corrode or leak or both. I think mine corroded and shorted internally. It did not appear to be leaking. In various boats over the years, I have replaced two other water heaters. I never try to repair them, not worth the effort.

So, I replaced the water heater. It was surprisingly easy, and took about three hours. When empty, the water heater only weighs about ten pounds. When removing the old one, I spent a bit of time draining it to get the weight down. When all done with the install, I also spent a bit of time cleaning the bilge. It was impossible to avoid getting some antifreeze from the engine into the bilge. It makes a mess. A wet dry vacuum is invaluable.

If you hire someone to do this, don't believe them if they say it will take 8 hours. It does not, and you can do it yourself.

Tim
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Re: Heating Fresh Water

Postby AlanH » Thu Oct 25, 2018 9:18 am

Tim,

I am sorry I didn't respond to your first post. We have been having a problem for several months with notifications from the forum being sent to spam. I change the settings and things are okay for a while, then back to spam. I would have said it is very likely to be a shorted out heating element in the hot water heater. I also would have recommended replacing the heater.

Alan
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Re: Heating Fresh Water

Postby Expatriate » Thu Oct 25, 2018 5:40 pm

Alan,

Thanks for the come back. I forgot to mention that I replaced a Kuuma with a Whale. It cost twice as much as the Kuuma. I hope it is twice as good.

Tim


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