Question about water heater setup on Hunter 36

A

AndyL

.
Jun 23, 2020
148
Hunter 36 Rock Hall
I have a 2004 Hunter 36 with a Force10 6-gal water heater that needs replacing. I'm replacing it with the identical model that is now made by Kuuma.

I can't find anything in the boat manual to say whether or not we have an expansion tank in the system... does anyone know whether or not we do and, if we do, where it is?

Thanks,
Andy
 
Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,150
Hunter 310 West Vancouver, B.C.
Only on a custom built boat. Test to see if an accumulator is installed by a previous owner.
 
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chuckwayne

chuckwayne

.
Mar 20, 2004
1,737
Hunter 356 and 216 Portland, ME
I doubt it- not installed by Hunter but could have been added by dealer/owner. doesn't affect water heater hookup. if there is one, look for a small tank somewhere under the sole near the water pump
 
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A

AndyL

.
Jun 23, 2020
148
Hunter 36 Rock Hall
OK - thanks.

Here's why I'm asking... my old tank has the Kuuma valve that regulates engine coolant flow into the heater when the engine is running, to stop hot water temps getting too high.



That valve is no longer made and there doesn't appear to be any substitute.

Has anyone who used to have the old valve shown above removed it when installing a new water heater? Did you have any issues or do anything special to accommodate the higher water temps and water expansion in the water heater?

Thanks.
 
Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,150
Hunter 310 West Vancouver, B.C.
My setup doesn't have any controls on the DHW and it's never presented a problem. Just make people aware that it COULD get very hot.

The accumulator tank is a necessity to keep the relief valve from weeping as the temperature comes up. If your water pump is a straight OFF/ON control, test to see if the pump keeps pumping after an outlet is closed. If the pump stops immediately, no accumulator OR the accumulator has failed. Your choice.
 
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A

AndyL

.
Jun 23, 2020
148
Hunter 36 Rock Hall
Ralph Johnstone said:
My setup doesn't have any controls on the DHW and it's never presented a problem. Just make people aware that it COULD get very hot.

The accumulator tank is a necessity to keep the relief valve from weeping as the temperature comes up. If your water pump is a straight OFF/ON control, test to see if the pump keeps pumping after an outlet is closed. If the pump stops immediately, no accumulator OR the accumulator has failed. Your choice.
Click to expand
The water pump stops immediately after an outlet is closed. I haven't noticed any obvious leakage from the water heater when it is turned on. I'll look around when I get down to the boat later in the week.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
22,746
CAL 35 Cruiser #21 moored EVERETT WA
AndyL said:
expansion tank
Click to expand
It is not called an "expansion tank"... it is known as an "Accumulator"

Two examples of what they look like.
Screen Shot 2022-09-27 at 3.49.47 PM.png
This is a Shurflo
Screen Shot 2022-09-27 at 3.51.09 PM.png
This is a Jabsco
Accumulator Tank - 20 PSI
Description
Pre-pressurized with built-in diaphragm, the Shurflo Accumulator Tank smooths water faucet pulses and reduces pump cycling to keep line pressure up and pump motors cool. Unlike other similar tanks, the Shurflo Accumulator incorporates a butyl rubber diaphragm to maintain pressure for years, rather than days with traditional tanks. Reduces cycling pulsation and pressure spikes, increases the life of your pump and even saves battery power.
• Ports: 1/2-14 NPSM male straight thread; will seal with 1/2" female NPT; second port may be capped, as applicable
• Pre-charged to 20 PSI
• Dimensions: 8.90"H x 4.06"D

Here is a third design. This is also a Jabsco
Screen Shot 2022-09-27 at 3.53.57 PM.png
 
chuckwayne

chuckwayne

.
Mar 20, 2004
1,737
Hunter 356 and 216 Portland, ME
Are you sure that 's regulating coolant flow? That sounds odd - because if you restrict the coolant flow there - it's one loop thru the engine- you restrict flow thru the engine. Since that valve is installed on the "hot out" connection, I'm betting it's a non-adjustable tempering valve that blends cold water (the red tube??) with the hot water to moderate the temperature on the faucets. I didn't have anything like that, so I added a tempering valve to protect the grandkids. about $35 for the valve on amazon and it works great; I could adjust the hot water down from 180 degrees to 120
 
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Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,150
Hunter 310 West Vancouver, B.C.
Hello Below said:
Which the fix to the latter may be a simple as recharging the accumulator with a bicycle tire pump.
Click to expand
You would have to introduce facts and complicate things :angry: !

Even with all of the compressed air removed from the accumulator, I'd expect the diaphragm to accept some water giving the pump a second or two to build up pressure. I've seen this in mine when the interior pressure near zero.

Definitely not proof positive but it "likely" means there isn't one in the piping and the OP wasn't able to find one to boot. Having two chambers will do even a better job if there is in fact a first one.
 
Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,150
Hunter 310 West Vancouver, B.C.
chuckwayne said:
Are you sure that 's regulating coolant flow? That sounds odd - because if you restrict the coolant flow there - it's one loop thru the engine- you restrict flow thru the engine.
Click to expand
One loop is through the engine and a parallel loop is through the HEX so no problem.

1664333235318.png



chuckwayne said:
Since that valve is installed on the "hot out" connection, I'm betting it's a non-adjustable tempering valve that blends cold water (the red tube??) with the hot water to moderate the temperature on the faucets.
Click to expand
That was my guess as well. Mighty fine SS casing on the heater tank.
 
RoyS

RoyS

.
Jun 3, 2012
1,742
Hunter 33 Steamboat Wharf, Hull, MA
You need a mixing valve at the hot water outlet to regulate output temperature and prevent scalding. I use a Honeywell AM-1 equipped with unions and threaded fittings on all three ports. There are also models of the AM-1 with pex or sweat fittings, so be careful with your selection. Reasonably priced, adjustable temperature setting, and reliable.
 
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Allan12210

Allan12210

.
Jan 22, 2008
1,661
Hunter 34 Alameda CA
AndyL said:
OK - thanks.

Here's why I'm asking... my old tank has the Kuuma valve that regulates engine coolant flow into the heater when the engine is running, to stop hot water temps getting too high.

That valve is no longer made and there doesn't appear to be any substitute.

Has anyone who used to have the old valve shown above removed it when installing a new water heater? Did you have any issues or do anything special to accommodate the higher water temps and water expansion in the water heater?

Thanks.
Click to expand
Can you just swap that from the old heater to the new one?

If it is indeed a thermal regulating valve, here's how I added one to mine. Rather than trying to regulate the engine coolant into the water heater, I chose to regulate the output into the rest of the fresh water system. Plus the added bonus was that it seemed like we had more heated water available when away from shore power. Not as much was purged from the water heater while we were trying to dial in the appropriate temperature.

Thermal Mixing Valve

I finally upgraded my water heater after reading the posts from Mainsail, Stu, et. al. to a safer system. As you all have no doubt discovered the hard way, the water that comes out of the tap after using the engine to heat it is really HOT. I find this out every time I leave the handle set from...
forums.sailboatowners.com
 
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A

AndyL

.
Jun 23, 2020
148
Hunter 36 Rock Hall
Thanks for all the feedback. Some answers:

- I did buy the Jabsco plastic accumulator tank shown above. Now I have to find a location to install and get the correct connectors. We have the 15mm red and blue plastic piping and it's not so easy to find fittings. It is also less flexible than normal hose, so that doesn't help because some locations would require too much bending so that either means a different location or adding more right-angled connectors (and I always prefer to use the minimum number of connectors).

- I will try to reuse the existing valve from the water heater but I want to be prepared with options if that fails.

- The valves that mix cold into the outgoing hot seem to be the only solution now so that may be the way I go unless I can reuse the old valve.

- The more changes I have to make, the more the hot and cold water pipe routing changes and, as mentioned, these plastic pipes are less forgiving of significant changes in location or direction.

- I am still working out how to get the engine coolant to drain without making a mess when I remove those pipes, plus how to avoid air when I reconnect them. I'm sure it's not rocket science :)

Regards,
Andy
 
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