I have been trying to figure out a way to heat the water in my freshwater wash down tank. I am an avid diver all year round and warm water would be a great thing. I have been looking for a way to install a heat exchanger for my four stroke outboard that would continuously circulate fresh water from the tank and warm water from the engine exhaust. Not sure if this is something that I can buy, or something I need to fabricate on my own. Does anyone have any ideas on this or any other ways to heat the water? I am limited on space for installing a Large hot water heater.
Heating fresh water wash down
- Thread starter Sparkdog118
- Start date
Legend
GreatGrady Captain
- Joined
- Jun 29, 2006
- Messages
- 1,462
- Reaction score
- 201
- Points
- 63
- Location
- Southern New England
- Model
- Sailfish
Not sure what size boat but on my 282 we have a factory installed hot water heater. It heats when connected to shore power but the water stay hot for a very long time. I have been out diving and 6 hours after leaving the dock the water is still very warm and comfortable for a quick shower. The tank is only 10 gallons and it fits in a pretty compact bow compartment.
I like the way you're thinking, so I've got 3 suggestions for you.
#1) To use the motor, essentially you'd have to tap into the "pee stream" or another spot on the outboard's cooling system (most of which is internal), route it outside the motor and into the transom, and then rig up some sort of heat exchanger into your FW tank like this:
Of course you wouldn't have any temperature regulation going this route, eventually your water tank would reach the 140 degrees of the engine which may not be a good thing.
So #2,
Alternately you could probably just add in a small 12v water heating element to your existing tank - and let's be honest you really don't want HOT water, since you can't mix, you want WARM water. I imagine if you mounted this on a stainless plate you could pull it off without risk to the tank but YMMV. You'd also want to figure out a thermostat system although with the small size of the element you may never need it.
mwands.com
Doing the math, you might need two, depending on how long your diving runs are and how hot you want the water to get. I like the idea of a low-power heating element though.
And then #3,
Last but not least, if you've got $ to burn, this really intrigued me and I thought about trying it with my own water heater: http://www.isotherm-parts.com/product-range/cooling-units/compact-systems/sp-cooled
Essentially, instead of plumbing the fitting to your hull, you'd just plumb this fitting to your freshwater tank. Like the heat exchangers above I'm sure there's plenty of motion in that tank to keep the water moving around it. This is essentially a heat pump - it will move the heat from the chill plate into the water tank. Again, you'll have no temperature regulation, and I don't know the actual wattage transfer or how hot it could get the water. But it would have the convenient side effect of CHILLING another compartment while heating your water, if all you do are day trips something like this might kill two birds with one stone, but I'd try to find a btu calculation for how much heat it would actually produce.
#1) To use the motor, essentially you'd have to tap into the "pee stream" or another spot on the outboard's cooling system (most of which is internal), route it outside the motor and into the transom, and then rig up some sort of heat exchanger into your FW tank like this:
0.250 ID Stainless Steel Heating Cooling Tubing Coil, Chiller/Heat Exchanger | eBay
Total weight of coil: 1 Lb, 7.30 ounces, 662 Grams. Grade of Stainless: Unknown. Sold as shown. TSF#: 6065.
www.ebay.com
Of course you wouldn't have any temperature regulation going this route, eventually your water tank would reach the 140 degrees of the engine which may not be a good thing.
So #2,
Alternately you could probably just add in a small 12v water heating element to your existing tank - and let's be honest you really don't want HOT water, since you can't mix, you want WARM water. I imagine if you mounted this on a stainless plate you could pull it off without risk to the tank but YMMV. You'd also want to figure out a thermostat system although with the small size of the element you may never need it.
6 Inch DC Submersible Water Heater Element
6 Inch 12 Volt and 24 Volt DC Water Heater Element from Missouri Wind and Solar. Use your solar panels, batteries, wind turbines, hydroelectric power to heat water and other liquids.
mwands.com
Doing the math, you might need two, depending on how long your diving runs are and how hot you want the water to get. I like the idea of a low-power heating element though.
And then #3,
Last but not least, if you've got $ to burn, this really intrigued me and I thought about trying it with my own water heater: http://www.isotherm-parts.com/product-range/cooling-units/compact-systems/sp-cooled
Essentially, instead of plumbing the fitting to your hull, you'd just plumb this fitting to your freshwater tank. Like the heat exchangers above I'm sure there's plenty of motion in that tank to keep the water moving around it. This is essentially a heat pump - it will move the heat from the chill plate into the water tank. Again, you'll have no temperature regulation, and I don't know the actual wattage transfer or how hot it could get the water. But it would have the convenient side effect of CHILLING another compartment while heating your water, if all you do are day trips something like this might kill two birds with one stone, but I'd try to find a btu calculation for how much heat it would actually produce.
I found a reference online that Moeller says their fuel tanks are good to 150 degrees. I'm assuming most plastic tanks wouldn't have an issue with normal 'showering' warm water temperatures of +/- 100 degrees.
You are an avid diver all year round, but you don't say whether that is in S. Florida or Maine. How many showers on a typical trip? For one or two, the Solar Showers work pretty well if you have good sunshine.
How big is your boat? Take a BIG cooler, one with slots on the sides so that you can add a couple of baffles, rig a livewell or bilge pump to the drain, and fill it with hot water before leaving the dock.
How big is your boat? Take a BIG cooler, one with slots on the sides so that you can add a couple of baffles, rig a livewell or bilge pump to the drain, and fill it with hot water before leaving the dock.
I am in a fla. I work from Orlando south. Tampa bay gets cold in the winter. Sometimes the air temp is 50 and the water is like 60 deg. When I am not working on boats, I install underwater navigation cable for a directional boring companies across waterways. Sometimes I am in and out of the water 8 hours a day. Would be nice to squirt warm water in my wetsuit once in a while. Lol. I will look into all these suggestions. I have a f115 Tamir on my little work boat so the p stream is cold water. I may have to see if I can pull water off the thermostat hose after it has been through the block. I have a f250 yami on my Grady for recreation diving.
Good point about tank temp. I have a 9 gal in my little boat and a 25 gal in my Grady. May have to put a ball valve on the hot water from the engine to regulate the temp. My 9 gal tank is above deck so I can watch it.