I am interested in circulating hot water to heat my boat. I have heard about and seen diesel fired systems and engine coolant water circulating systems. Why not incorporate the electric hot water heater into a circulatory system using a "hot water circulating pump", these are used in commercial applications so that the hot water is always at the point of use. It just keeps the hot water moving through a looped system all of the time. The hot water system would have independent coil units (radiators) with fans...same as the ones for the other type systems. It seems possible...one draw back I see is the hot water heater size...if you take a long shower and deplete the hot water the boats heating system will have to recover as well. In the summer, switch off the circulating pump and turn a valve to isolate the loop from the hot water heater. One could have two heaters in series or isolate one? Hot water is something that is necessary and instead of finding other ways to produce it...let it produce the heat for the boat. Why add another complete system to produce heat when it already exists on most boats...the hot water heater? We run the gen set for the AC in the summer...why not run the gen set for the hot water and heat in the winter? You have to run something! A well insulated hot water heater and piping system could be an efficient way to have hot water and heat the boat. A 19 gallon domestic hot water heater uses little more power than a 1500 watt ceramic heater..I think? Maybe some copper tubing in the cabin sole? :>) Heated towel bars... You can see that I am no engineer, and this is full of holes, but I am hoping for some constructive input. Bob Clinkenbeard Custom Roughwater 41' Trawler "Bobbin Along" http://www.dreamwater.org/captainbob/

A hydronic heating system on board makes for a comfortable boat! The radiators don't know, or care what device is warming the water. Electric could work, and is occasionally used as a backup to the primary system. The problem with hot water heater as your source would be BTU/Hour. A 1500 watt element converts to 5,118 BTU/Hour. Most marine boilers start at 45 thousand and go up from there. I have 400K on board. I might suggest that you contact one of the boiler manufacturers or a good local heat/ac place and get an estimate of how many BTU/Hour you will need under the expected conditions and then see what choices are available. Let me know if you have further questions, Mike At 10:46 PM 2/12/2005, Bob Clinkenbeard wrote: >I am interested in circulating hot water to heat my boat. I have heard >about and seen diesel fired systems and engine coolant water circulating >systems. >Why not incorporate the electric hot water heater into a circulatory >system using a "hot water circulating pump", these are used in commercial >applications so that the hot water is always at the point of use. It just >keeps the hot water moving through a looped system all of the time. The >hot water system would have independent coil units (radiators) with >fans...same as the ones for the other type systems. >It seems possible...one draw back I see is the hot water heater size...if >you take a long shower and deplete the hot water the boats heating system >will have to recover as well. In the summer, switch off the circulating >pump and turn a valve to isolate the loop from the hot water heater. One >could have two heaters in series or isolate one? >Hot water is something that is necessary and instead of finding other ways >to produce it...let it produce the heat for the boat. >Why add another complete system to produce heat when it already exists on >most boats...the hot water heater? >We run the gen set for the AC in the summer...why not run the gen set for >the hot water and heat in the winter? You have to run something! >A well insulated hot water heater and piping system could be an efficient >way to have hot water and heat the boat. >A 19 gallon domestic hot water heater uses little more power than a 1500 >watt ceramic heater..I think? > >Maybe some copper tubing in the cabin sole? :>) >Heated towel bars... > >You can see that I am no engineer, and this is full of holes, but I am >hoping for some constructive input. > >Bob Clinkenbeard >Custom Roughwater 41' Trawler >"Bobbin Along" >http://www.dreamwater.org/captainbob/ Mike Cowan MV Sue's Pool III 65 Hatteras LRC hull #2 Off-List email: mikec@wirelessconnections.net

Bob, Have you checked into these folks? http://www.rdac.com/index.html All I know is that they make heaters that use hot water. I haven't done much investigating so it may not apply to your application at all but looks interesting. Good luck, Bill