I am insulating my tank with polyisocyanurate foam from home depot. Its essentially cream colored polyurethane foam with aluminum foil. I would not use Great Stuff for anything except to adhere the foam pieces or fill gaps- it is messy and difficult to control. It dries rubbery and doesn't sand well. The stuff I use is chemically identical, except it is a more dense version, and I use it for fairing and adhesive.
I think your attwood tank is functioning as designed. My previous tank owners' manual says 1 hour to heat water with the engine and it is a 6 gallon tank. You have a larger tank with 11 gallons others might be using smaller tanks (6 gallons) so they get faster heat times. The design flaw with these tanks is that the engine coolant loop is just a small U shaped loop with very little surface area. I know this because the previous tank split in half before I bought the boat. The Isotherm tanks which are arguably top of the line, have much more surface area in their heat exchange loop. Plus they are 316 stainless steel. If you don't have the time to mess with your tank you might consider pulling it out, selling it on ebay (they tend to sell for decent prices) and buying the Isotherm and saving yourself the hassle of what appears to be an extensive multi-day project with only marginal improvement. I have contemplated somehow running a solar collector to the shower as well. If you do undertake this project I would want to see how it works. It sounds feasible if you get a black powder coated aluminum solar pool heater from ebay and pump (using a 1 amp 12v pump) fluid through the second heat exchange loop of the isotherm. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Lee Haefele Sent: Wednesday, November 21, 2007 10:48 AM To: [email protected] Subject: [Liveaboard] Hot water project I would like hot water for showers and dish washing without running the engine. Would also like to improve time the engine takes to heat water. I have an Attwood 11 gallon heater, it seems to have ~1/2" of fiberglass insulation, at least on the front where I can see. I have new Westerbeke 44B motors, the antifreeze circulates from below the thermostat, to the water heater and back to the water pump. The previous Westerbeke 42B engine tapped water with a restricting double "T" that was inline to the heat exchanger. Neither arrangement would heat water at idle, both took 1-2hrs at cruise speed. There is an expansion tank plumbed in the antifreeze output line of the heater, it is such that all water flows through, it holds about a gallon and takes about 5 minutes to heat after the hoses are very hot. So I think flow is less than 1 quart/minute. I am going to replumb this so that the hot water flows directly back to the engine and the tank is on a "T". Doubt this will make much difference. The exit water is colder than the entry water, possibly by 30 degrees, but it is hard to get a good reading on a rubber hose. Other boaters heat water in less than 1/2 hour, why is mine slower and what can I do to improve it? Is there a better place to tap hot antifreeze? I have 4 120W solar panels and usually have some excess energy, however, I have a Blue Sky MPPT controller that does not switch excess power to a load. Possibilities: Foam insulate existing heater (What to use? Great Stuff brand?) and use either a 12V heating element or a 240V element run on 120V from the inverter (This will give 1/4 wattage), combined with a wind up timer switch. Automatic operation would be much better, is there any way I could use a Blue Seas adjustable battery combiner for this? Any other ideas? Big $$ idea: Replace heater with Isotherm model 40DS, ~$800?, this has foam insulation, a double loop in the exchanger tube and this model has 2 exchanger loops. Could I plumb a solar water collector in to the second loop? This could be as simple as a coil of black pipe, but would need a pump and controls. I have heard of some mini solar pumps, what I find is expensive. I could plumb a coil of hose in line with the shower, but I normally shower not at times of hot sun. It seems silly to have tropical sun and no hot water. Lee Haefele Leopard 38 cat Alesto 2
_______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
