On demand propane hot water heaters

[pjfsail]

Do any of you cruisers have any experience with, On demand propane hot water heaters? I would appreciate listening to your experience and what brand you are using. Thanks, Peter

[Thermal]

I have one of these, though not on my boat. I would think that it would not be practical on a boat since they use quite a bit of propane, those little 20# bottles would not last very long. They also aren''t that good in cold climates since the water can freeze in there when it''s not in use, and it''s difficult to drain completely. the one I have is made by Bosch and seems to be well made.

[TrueBlue]

My Nauticat has a Junkers (German) on-demand propane hw heater. During the pre-purchase inspections-trials, I thought I would replace it with a conventional engine heated/electric tank, such as we have had on former boats. However, after MUCH use for several weeks at dock & two-night overnighters, I have grown to prefer it.

I have two 11 lb. aluminum cylinders, each in dedicated propane lockers located within the side decks and have not had to refill yet. The prior owner claimed one tank lasted him all season, although I''m not certain how often he used the boat. Our upcoming two-week cruise will be a great test, coupled with a 140 gal water tank, I don''t anticipate problems.

The greatest advantage is instant, unlimited hot water, any time. We cannot open the tap to full hot when showering. The water gets scalding hot . . . a great luxury for cruising sailors. The only negative side is the pilot flame. I will not leave it lit when we''re not on the boat, just too risky for my comfort. It is easy to relight though, just open the valve & press the ignitor button. As far as winterizing goes, no problem at all. Simply open the brass **** on the unit''s bottom and all water is drained.

My boat''s installation is original and very well done. Whenever our boat-experienced guests see and use the system, they are very impressed. If installing one as aftermarket, for safety concerns, I highly recommend a professional. I would also highly endorse the system for people who do a lot of cruising. If plugged into shorepower most of the time, a tank heater is the way to go.

Steve

[Jeff_H]

I am not familiar with the Junkers. Do they have an exhaust flue and intake air vent. I have considered using one of these on demand systems on my boat. There is a serious hazzard with the unvented type with regards to carbon monoxide poisoning and oxygen depletion problems.

Jeff

[TrueBlue]

Jeff,
That was exactly my earlier concern as well. However, upon close inspection, I came to realize how safe the system is. This installation incorporates a stainless steel hood (not unlike a Viking gas range) secured independantly over the top of the bulkhead-mounted heater. The fume extractor is side-vented through the galley teak interior paneling and exterior FRP by way of an exterior-pitched metal sleeve, fitted with a circular metal damper at the outlet. The damper can be screwed in (inside/outside control) when sailing in foul weather, or out when in use.

I was very impressed by the quality of installation . . . I design high-end buildings, like you, and have grown accustomed to quality craft & materials.

My propane oven/cooktop is vented via an operable hatch just overhead and as previously mentioned, the regulated cylinders are on the exterior, in vented lockers. As you know, propane sinks and could present hazards in faulty installations.

Edit: I forgot to mention that Junkers was bought by Bosch who continues to use the Junkers name on some of their high-end products.

Steve

[pjfsail]

Steve, I appreciate so much you reporting your experience. I used Google to do a search and found there are several different models of Bosch On Demand Hot Water Heaters. Can you tell me which model you have? Thanks again, Peter

[pjfsail]

The web site, http://www.houseneeds.com/shop/specials/specialitems1.htm, offers a number of Bosch Aquastar On Demand Propane Fired Hot Water Heaters for sale. They have pilot light heaters along with battery sparked, and even a hydrospark unit. I would be interested in the battery sparked, model # 125X. Anyone else have any experience with On Demand Propane Fired Hot Water Heaters?
Thanks, Peter

[sneuman]

I can only speak of on-demand water heaters in general. They are common in households in Asia. Work wonderfully - unlimited hot water instantly; they are also very efficient, heating only when needed, not wasting gas/electricity to keep a pot boiling (or near boiling). I have been living in Asia for several years now and cannot understand why this idea hasn''t caught on in the states. Just makes too much sense. But, like many other things, the USA is WAY behind vis-a-vis the rest of the world.

[JeffC_]

Sneuman, I believe that has much to do with North Americans'' having, historically speaking, abundant natural resources, so see no need to husband those resources. Much of America''s approach to energy use, IMHO, simply has to do with the lack of incentive to be efficient.

I''m not a pessimist, just a keen student of human nature. Until folks actually feel a hit in their wallets, lifestyles or national prestige (remember the Space Race?), efficient ways to produce/store/use energy will remain undeveloped or under-utilized, and those who go outside the mainstream will be regarded as a bit kooky.

The implications for the sailing fraternity are self-evident.