tankless hot water

[Pblais]

Can you tell me about the maintenance of the unit. Have been reading the specs very impressive, states that at 2 gpm the unit will use 20lbs of lpg to heat 940 gallons of hot water. Have not been able to find the max hot water output can you give me a idea.

We use a Bosch 38B. It weighs 18 lbs empty. It is rated between 20,000 BTU's to 40,000 btu's depending on pressure. At 13 psi it will put output 1.3 GPM and will handle up to 150 psi (not on my boat). I don't have exact gallons of lpg numbers but what we can do is adjust the flow rate with a dial on the front of it.

The work to keep it serviced is not much. Ours is bolted to the wall of the shower and I can take off the cover in a minute and then start removing the parts. It's pretty small in size and has no moving parts. The unit has a small heat exchanger surrounding the burner. You have to manually adjust the pilot valve to get the correct flame. It works exactly like natural gas a home hot water heater as far as lighting it goes. I do not keep it lit all the time as I don't leave the propane on all the time either.

The flow regulator just slows the water flow and forces it to get hotter. It clearly is hotter than you need for a shower even where you want to waste a lot of water. At lowest flow it's too hot to shower with and full flow it's perfect for sumertime showers. Both of these exclude mixing with cold water and of course you could do that. On the hook it's going to be be a lot less water so the lpg requirement drops (if you expect to keep a large supply of water). At the dock you can take a 20 minute shower if you wanted to.

All I have to do is winterize it with antifreeze. The instruction talks about lubricating the water valve every few years with a rebuild perhaps on a 5 year interval. You can operate it with the cover off to inspect it easily. I find I have to adjust the pilot somewhat often. It's just a small wrench with the cover off to adjust it. It is exceptionally easy to disassemble. I wouldn't try that with a conventional tank.

As far as cost, the nice stainless 7 gallon tanks work well so price them as a comparisson. I had one in the last boat and they do heat fast and make enough water for two people and cleaning the dishes after you run the engine and the water is warm in the morning to a degree. Replacing a hot water tank is no picnic nor is installing one correctly so you gain a little bit on the installation after you run a propane line. You sure can't repair a hot water tank. The 38B is the only one that is ventless. How you would handle a vent is the perhaps only negative item I can think of since it has to go through the deck.

Our unit was installed by the original owners in 1991 and they cruised 40,000 miles for 5 years. It was then lived aboard in Delaware for over a year (I'm confident it was used every day and was 100% neglected) and it still works fine. I wouldn't say they are temperamental.

[Pblais]

My local RV shop is suggesting a BOSCH shower mate but I have a feeling this is the Cadallac and I only need a Volkswagon.

I took a quite peek at the specs on these. These seem really nice. About 15% more heat than ours. The fact that it is ventless makes up for the cost. Installing a vent would not be easy nor convienient.

[Kanani]

We had a Bosch LPG water heater on our boat for over 10 years. It had the manual pilot light and I liked it.

The unit was mounted in my engine room (under the center cockpit) and was vented to the outside. The engine room was also vented.

We always had hot water in both showers (fore & aft) and the galley and never had a problem with the unit. The first few seconds of our showers were always exciting but we didn't mind.

I don't remember the model # but is was rather large (about 10"x10"x24")

[tomj]

We installed a "Paloma" LPG 'on demand' heater (bought from Defender's) in our Alberg 37 years ago (in the late 80s I think - but we've owned the boat since 1982), and it still works great with absolutely no problems. We installed it in the head, where we only use the heater for showers (sure is nice to take a hot shower in the early spring and late fall!....and you'd be surprised how a little water can be effectively used) - as it would take far too much water to get hot water to the galley. Of course the Paloma is vented, with a proper deck fitting (Cole Cap). The heater requires no electricity (piezio push button lighter), uses a thermocouple to limit gas flow if the pilot light goes out, etc. We only keep the pilot light on while the heater is in actual use.
During our last (1993) Insurance in-the-water survey by Boat US, the surveyor (his only experience in boat surveying was commercial barges!!!) griped the water heater, as it had a small sticker stating "not to be used in a confined space" which he took to mean even if vented. The week following the survey I received a very concise letter from BUS stating that the Paloma was to be removed immediately!!

Anyway, I happened to remember that sometime before we installed the Paloma heater, Practical Sailor did a review of the exact same Paloma heater, and the use of this heater on a sailboat was discussed......and I paraphrase: "and Boat US Insurance considers the Poloma heater as an 'attended propane device' (i.e., like a galley stove), and would not deny insurability if a Paloma was properly installed"

Needless to say, I made a copy of the PS review and mailed it along with my response to the BUS Insurance Denial notice. About a week later, I received a letter from BUS stating "ahem,,,upon further consideration, insurability in this matter is not denied...." !

As in all things related to boating, one is expected to use common sense in the installation, use and maintenance of boating equipment - boats are not too tolerant of fools and idiots....

[Microship]

Tomj - very interesting... thanks! I think I need to fight this; your post is encouraging.

Happy new year!
Steve

[ColdEH]

I have a Propane on demand water heater on board, it works great , took me awhile to get it balanced but now works as it should. It is made by Excel , 45000 btu's Oxygen depletion sensor type. I have it mounted in my engine room that has a constant running vent so the gases are removed as soon as they are present. Also have a propane sniffer in the bilge with a cut off valve . I really think the key to propane safety on board is to get the very best hoses and fittings posible and keep everything in good shape.The unit runs flawlessly. If you decide to live on your boat as we do , you really don't want to give up to many of the land based luxuries.

Regards John.