run yan engine w/o hot water heater full?

M

MitchM

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Jan 20, 2005
1,031
Nauticat 321 pilothouse 32 Erie PA
yan 3jh4e 40 hp diesel, 5 yr old 300 hours, has 2 hot water hoses ff the thermostat block which circulate hot antifreeze-filled hoses through the water in the Isotherm 24 liter hot water heater to heat the w after up when the engine is running. (the heater hoses off the engine block feed into a stainless steel closed loop inside the HW heater.)

the HW heater blew a seam, the water leaked out. the heater hoses are still attached to the engine (and it's a closed system). hoses are rated 220degrees F and 70 PSI.

is there any problem in running the engine (for 20 minutes) to get to the haul out, even though t here's no water in the hot water heater engine hose loop ?

all thoughts and advice welcome .. we haul out this week end and there's not enough time to rip out the old HW heater and replace with new before then...
 
Ron20324

Ron20324

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Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
Like a winter lay-up, take the two hoses off the water heater and connect them with a barb-to-barb connector to form a loop back to the engine. Refill engine with proper mixture off anti-freeze & distilled water.
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,050
Catalina 34 224 Maple Bay, BC, Canada
MitchM said:
the HW heater blew a seam, the water leaked out. the heater hoses are still attached to the engine (and it's a closed system). hoses are rated 220degrees F and 70 PSI.
Click to expand
Does this mean the drinking water leaked out? If so, and the circuit for the engine coolant is still OK, no problem. You could also simply bypass the coolant loop by connecting the out & in right at the engine, which is the way they came from the factory before water heaters were installed. Good luck, sorry to hear your high quality heater blew.
 
Skipper

Skipper

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Oct 9, 2008
1,742
Bristol 29.9 Dana Point
It won't hurt it. An empty heater is only a problem for the electric heating element, should it be energized.
 
Ron20324

Ron20324

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Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
Skipper said:
It won't hurt it. An empty heater is only a problem for the electric heating element, should it be energized.
Click to expand
OP said, "even though t here's no water in the hot water heater engine hose loop ? "
 
Ken13559

Ken13559

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Oct 29, 2005
2,362
Hunter Marine 326 303 Singapore
If its the hot water tank that is leaking and the engine coolant loop is still good, then should be no problem. But if the coolant line is leaking then you've to fix it before your journey.
 
Allan12210

Allan12210

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Jan 22, 2008
1,666
Hunter 34 Alameda CA
Ron20324 said:
OP said, "even though t here's no water in the hot water heater engine hose loop ? "
Click to expand

It is confusing verbage. So, my $0.02:

Scene 1: The seam that blew refers to the fresh water side. No problem circulating hot engine coolant to/from the water heater. Turn off water pressure circuit breaker or you'll drain the fresh water tank into the bilge.

Scene 2: The seam ruptured refers to the coolant loop somewhere. That means no engine coolant. Bad. Do not operate the engine unless the input and output of the water heater heat exchanger are connected together in a loop either at the engine or at the water heater. I do it all the time on my truck when the heater core corrodes through and the antifreeze fogs up the inside of the windshield. Then when winter comes and I can't stand being cold any longer, I fix it.

Depending on which it is, take the appropriate action.
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,709
Canadian Sailcraft 36T Casco Bay, ME
MitchM said:
the HW heater blew a seam, the water leaked out. the heater hoses are still attached to the engine (and it's a closed system). hoses are rated 220degrees F and 70 PSI.
Click to expand
Are you sure the relief valve (T&P) is not what blew? If your engine is running hot this could cause the T&P to pop open if the water in the tank got to 210F....

MitchM said:
is there any problem in running the engine (for 20 minutes) to get to the haul out, even though t here's no water in the hot water heater engine hose loop ?
Click to expand
As long as your HX circuit/loop is fine then there are no issues running the motor as all you are doing is heating the air inside the tank as opposed to water.....
 
pateco

pateco

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Aug 12, 2014
2,207
Hunter 31 (1983) Pompano Beach FL
I have the other side of this problem. Last night while motoring to a waterfront restaurant for dinner, I noticed the bilge pump kick on more than once. Boat is normally dry below, so I knew something was wrong. Went down below and had water on the sole in the Galley running from under the cabinet in the sink area. First fear was sink drain thru hull, but that looked good and was dry. Then however, I looked further back in the sink cabinet to where the water heater lives in the front end of the starboard lazarette. Water was dripping out of the bottom of the heater. I checked the hoses and connections, and they were fine. So I think the heat exchanger in the HW Heater has failed, and since I have a Yanmar 2GM20, I am leaking Raw water engine coolant into my bilge. I need to buy a Barb fitting, and bypass the heater ASAP. and then I need to decide If I am going to replace it, and if so with what. The raw water heat exchanger never did anything to heat water in the water tank, so what small heater would you suggest to replace it without a heat exchanger?
 
Skipper

Skipper

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Oct 9, 2008
1,742
Bristol 29.9 Dana Point
Ron20324 said:
OP said, "even though t here's no water in the hot water heater engine hose loop ? "
Click to expand
Well yes then that would be a problem. :-0

But most of his post indicated (to me) that it was the domestic water that had leaked out.
 
M

MitchM

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Jan 20, 2005
1,031
Nauticat 321 pilothouse 32 Erie PA
recap of the problem and its solution : the Isotherm isotemp $800 hot water heater, 10 years old, has both an overheat and a regular thermostat. the overheat is a safety that shuts off power , the regular maintains the temp. the manufacturer unwisely chose to attach the OH thermostat probe to the control circuits with a press on copper tab. unknown to me the tab fell off the OH control box. the HWH totally overhead so badly it blew the AC cir it breaker , fried the heater element and warped the HWH body. so the HWH would not hold pressure. (NB in teaching my marine electric course I tell students ABYC requires a proper connection for marine wiring -- a push on tab or a ring. I guess Isotherm didn't take that class.) so i had a HWH with 2 good closed-loop connections carrying antifreeze from the engine thru a closed stainless loop to heat theoretical amounts of water in the HWH, and 2 open holes: one where the fresh water tank inlet came in to the HWH and another where the hot water came out. I connected the HWH inlet and outlet freshwater connections together and figured out a way to add pink antifreeze to winterize the hot water supply lines into the head and galley then use my trusty VIAIR compressor that pressurizes our tires in our RV. . which worked faultlessly.)
my concern was that if i ran the engine with the antifreeze loop system not submerged in h 2 0 , the temperature of the hoses might exceed their rating. Niemec marine a bronze Yanmar dealer out of new Bedford told me i should have no worries as the temp and pressure rating of the engine coolant hoses were rated at 220 F and 70 psi. so i singlehanded and ran over to the travelift for haul out without incident... in 27 knots of wind with full harness and jack lines. engine temp was no problem.. thanks to all for your helpful comments...
 
M

MitchM

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Jan 20, 2005
1,031
Nauticat 321 pilothouse 32 Erie PA
I looked further back in the sink cabinet to where the water heater lives in the front end of the starboard lazarette. Water was dripping out of the bottom of the heater. I checked the hoses and connections, and they were fine.
CHECK FOR A FAILED PRESSURE RELIEF VALVE ON YOUR HWHW FIRST. PUT SOME COLORED PAPER NAPKINS ON THE FLOOR UNDER YOUR HWH AND SEE IF YOU CAN tell where it is leaking from .

"...So I think the heat exchanger( WHAT IS THIS ? THE ON - ENGINE HT EXCHANGER ?) (or the closed coil inside your HWH?)
in the HW Heater has failed, (NB Inside the HWH is likely to be a closed loop carrying colored engine antifreeze through the water in your heater. if engine AF is leaking into the water coming out of your HWH that is another problem. the heat exchanger on the engine block might be leaking but you'd see antifreeze under the engine not at the HWH. )


"and since I have a Yanmar 2GM20, I am leaking Raw water engine coolant into my bilge." (NOT SURE HOW YOU CONCLUDED THIS ? engine AF in the bilge under the engine may be from from the ht exchanger on the engine itself or from leaking supply hoses from your freshwater aka antifreeze pump which is located under the engine , not near your HWH.


I need to buy a Barb fitting,(GO TO HOME DEPOT BUY A MALE 1/2 inch hose barb and a female 1/2 inch and screw them together then couple them into the hose ends. ) and bypass the heater ASAP. and then I need to decide If I am going to replace it, and if so with what. The raw water heat exchanger never did anything to heat water in the water tank, so what small heater would you suggest to replace it without a heat exchanger?[/QUOTE]

do you have engine antifreeze coolant hoses coming off your engine near the thermostat ?
 
M

MitchM

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Jan 20, 2005
1,031
Nauticat 321 pilothouse 32 Erie PA
NB: the above post was a reply to the thread from PATECO about his leaking HWH...
 
pateco

pateco

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Aug 12, 2014
2,207
Hunter 31 (1983) Pompano Beach FL
MitchM said:
"...So I think the heat exchanger( WHAT IS THIS ? THE ON - ENGINE HT EXCHANGER ?) (or the closed coil inside your HWH?)
in the HW Heater has failed, (NB Inside the HWH is likely to be a closed loop carrying colored engine antifreeze through the water in your heater. if engine AF is leaking into the water coming out of your HWH that is another problem. the heat exchanger on the engine block might be leaking but you'd see antifreeze under the engine not at the HWH. )
"and since I have a Yanmar 2GM20, I am leaking Raw water engine coolant into my bilge." (NOT SURE HOW YOU CONCLUDED THIS ? engine AF in the bilge under the engine may be from from the ht exchanger on the engine itself or from leaking supply hoses from your freshwater aka antifreeze pump which is located under the engine , not near your HWH. do you have engine antifreeze coolant hoses coming off your engine near the thermostat ?
Click to expand

MitchM,

This is a Raw water Cooled 2GM. No antifreeze, no on-engine heat exchanger. Raw water output from engine block was passed through HWH to attempt to heat water before returning back to the mixing elbow. Since this cooling system is not recirculating antifreeze/coolant, and is instead pulling cold raw water, the output from the engine while warm, was never hot enough to heat the water in the HWH.

I bypassed the HWH with a barb fitting, and the leak has stopped. I now have a dry bilge under the HWH.

I don't normally run the pressurized water system on the boat, ( maybe turned on for 10 minutes once every couple of months),but I turned it on to see if that side of the HWH system was also leaking, and it was. So I have also bypassed the HWH for the Sink/Shower water.

Now I just need to remove it entirely, and figure out what if anything I am going to do to replace it.

Looking at this one Super 900 Series 0.5 GPM (3 kW/110V) Tankless Electric Instant Water Heater



Plastic Copper and Brass construction with no Heat exchanger from the engine.
 
M

MitchM

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Jan 20, 2005
1,031
Nauticat 321 pilothouse 32 Erie PA
be careful with tankless electrics intended for homeowner use. in a home, those heaters need a 240 volt supply not a 120 v. the amp draw for this heater is too much for 30 amp shore power circuits. they usually need 50 amps . so i'd advise against putting this unit on a boat.

with your engine raw water cool only i don't believe it is recommended to try to do a hot water loop off the engine block or ITS heat exchanger to heat up your HWH . you might just get a small 4 gallon HWH to run at dockside while connected to shore power.
 
pateco

pateco

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Aug 12, 2014
2,207
Hunter 31 (1983) Pompano Beach FL
MitchM said:
those heaters need a 240 volt supply not a 120 v. the amp draw for this heater is too much for 30 amp shore power circuits. they usually need 50 amps . so i'd advise against putting this unit on a boat..
Click to expand
Features
  • On demand hot water
  • Multiple applications
  • Consumes less energy
  • Space saver
  • Equipped with overheat protection
  • Wall mountable
  • Product Type: Tankless Water Heater
  • Finish: White
  • Hardware Finish: Brass
  • Material: Plastic/Copper
  • Hardware Material: Copper
  • Tankless Capacity: 0.1 Gallons
Generic Specifications
  • Voltage: 110
  • Wattage: 3000
  • Safety certifications: UL listed
Dimensions
  • Required wire size: 10 AWG

My Calculations put it close at 27.27 amps
 
M

MitchM

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Jan 20, 2005
1,031
Nauticat 321 pilothouse 32 Erie PA
pateco said:
Features
  • On demand hot water
  • Multiple applications
  • Consumes less energy
  • Space saver
  • Equipped with overheat protection
  • Wall mountable
  • Product Type: Tankless Water Heater
  • Finish: White
  • Hardware Finish: Brass
  • Material: Plastic/Copper
  • Hardware Material: Copper
  • Tankless Capacity: 0.1 Gallons
Generic Specifications
  • Voltage: 110
  • Wattage: 3000
  • Safety certifications: UL listed
Dimensions
  • Required wire size: 10 AWG

My Calculations put it close at 27.27 amps
Click to expand
 
M

MitchM

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Jan 20, 2005
1,031
Nauticat 321 pilothouse 32 Erie PA
that would be a very interesting solution to the HWH problem. would they let you buy one, take it to the dock, fill with h 2 0 and plug in to 30 amp, and if it does not work on 30 amps can you return it?
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,709
Canadian Sailcraft 36T Casco Bay, ME
pateco said:
Generic Specifications
  • Voltage: 110
  • Wattage: 3000
  • Safety certifications: UL listed
Dimensions
  • Required wire size: 10 AWG

My Calculations put it close at 27.27 amps
Click to expand
Waaaaayyyyyyyy too much power draw for a 30A shore powered vessel!!!! You would need a 50A service, bare minimum, for that beast.....
 
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