On Demand Propane Water Heater?

[Stephen Trapani]

How will it handle the elements? Is it designed for outdoor installations? How will you route the water supply to it? The LPG supply?

Remember it is your boat you can do what you want to I am just posting relevant accepted safety standards. If you've read the standards and think buying an ISO9001 "certified" water heater then by all means go for it. Me, I'd spend the money on a dedicated marine rated unit, perhaps one that can be heated off the engine and electrically.

Well, as Peggy showed, far more people die on boats from electrical accidents than propane don't they, so where is the advantage? Secondly, I already use an electric water heater, could get a new one, but if possible would prefer something I can use at anchorage, without shore power and without having to triple my battery bank (225ah as it stands). Third, my motor is a tiny 2qm15. If you know of anyone who is heating their water with that little thing, let me know. The water in mine never gets to 120 until I turn it off, so as best I can figure, won't heat my water sufficiently. So, any ideas? BTW, thanks for the replies everyone. This is very helpful.

 

[Bill Roosa]

Two thoughts

On electrical appliances on boats: Life is tough; it is tougher if you are stupid. I think you will find that those who managed to kill themselves with electricity on boats either failed to do routine maintenance or were sticking their fingers into circuits that are energized. We understand the behavior of electrons pretty well, there is no excuse (except stupidity) for anyone to get electrocuted or set on fire in the 21st century.
I would never try to heat water with electricity without shore power.

On using a small water cooled engine to heat water; get a hotter thermostat, insulate the coolant lines to the HW tank and fresh hot water to the faucets, shorten up the coolant and supply lines to the maximize extent possible. Fully 70% of the energy in your fuel is converted to heat that the cooling system has to get rid of. I find it hard to believe that your 15ish HP motor (=37500 watts, 26250 watts as waste heat) can’t deliver 3% (1000 watts) of this as heat to your hot water heater.
My suspicion is you want to take a 15 minute shower which would require 30ish gallons of water. Even if I did have some way to heat that much water it would kill my water budget. So my question to the group intending to take long hot showers is where are you getting the water?

Boats are systems, you need to design them as such.

 

[Stephen Trapani]

On electrical appliances on boats: Life is tough; it is tougher if you are stupid. I think you will find that those who managed to kill themselves with electricity on boats either failed to do routine maintenance or were sticking their fingers into circuits that are energized. We understand the behavior of electrons pretty well, there is no excuse (except stupidity) for anyone to get electrocuted or set on fire in the 21st century.
I would never try to heat water with electricity without shore power...

Exactly my point! It's stupidity that's the problem, not electricity or propane. So let's look at this situation another way. I understand why you all assume the lowest common denominator. After all, I could be as stupid as a lampost, you don't know. But let's assume I'm not for a sec. Let's say I have a CO detector in the cabin. Let's say I have a propane detector near the motor/bilge pump. Let's say I have a 12v on/off switch for the propane system on the breaker panel. Let's say the on demand water heater is only used as a previous poster said, on demand, so in a sense it is attended. Let's say I use all this stuff wisely. NOW why shouldn't I install the Excel? (Oh, BTW, this has nothing to do with long showers. I just want hot water off the grid and I am loath to make cooling changes to a motor that still looks new after 31 years)

 

[Ross]

I get my hot water the old fashioned way, I heat it on the stove. Then I store it in a two quart thermos style pump coffee dispenser.

 

[Hermit Scott]

Well, as Peggy showed, far more people die on boats from electrical accidents than propane don't they, so where is the advantage? Secondly, I already use an electric water heater, could get a new one, but if possible would prefer something I can use at anchorage, without shore power and without having to triple my battery bank (225ah as it stands). Third, my motor is a tiny 2qm15. If you know of anyone who is heating their water with that little thing, let me know. The water in mine never gets to 120 until I turn it off, so as best I can figure, won't heat my water sufficiently. So, any ideas? BTW, thanks for the replies everyone. This is very helpful.

Your 2Qm15 will do a fine job of heating water for the water heater, provided it is not a raw water cooled engine. Do you have a heat exchanger on the engine? That is definitely your safest and simplest way to heat the domestic water supply.

The on demand system doesn't sound bad, but it would definitely be safer to go with something marine rated. You are not going to be able to mount that on the rail with out is falling apart inside.

 

[JoeD]

There is no reason not to install one. I have sailed on a few boats that have them and all work well. many have replaced their old Palomas with this unit. Yes, there is a reason for that. This one works as advertised.

Standard Disclaimer, Have nothing to do with this company except a very happy costmer. As for the amount of propane usage less than a small single burner on stove.

Look on this site and you will see from years ago a few installed them. If installed correctly they are as safe as you stove oven and maybe more so because of the auto shut off. I have CO and Peopane dector also. Better safe than dead.

It is a personal choice, If you use your boat as a condo go with Electric. If you sail like I do then you need Propane. Am on the Hook most of the time and a marina once in a while. Last year when I sailed to Flordia from Baltimore was very surprised how many people went from Dock to Dock. They sure missed some beautiful anchorages and good fishing . Only hit the fuel dock for fuel and Pump out. Did take marina One night in GA because of high winds forcast at 75mph. No fun on the hook at that speed.

Joe

 

[Bill Roosa]

Different usages result in different needs

As I see it we are coming up with different "needs" because we use our boats differently. AC electric and engine works for me. If I was a better sailor and could sail up those rivers and creeks to those snug anchorages, and had more wind and solar DC production capability then I could certainly see gas water heat as a nice option to engine coolant. If I was making passage and spending all my time on the hook this would be a very nice option but I'd need to invest in (probably would anyway) more DC electric production capability.
I'd still want a closed vent system with NO possibility of propane and flue gases getting into the cabin but that is just prudent engineering and following the instructions.
Since this would be a refit, I'd have to reroute the hot water lines for the heads/galley in a major way and figure out how to run the gas line and get more solar (where do I put that) or wind (same question). This would open up some under seat storage though and eliminate that potential engine coolant water leak in an unobservable location. It would also free up my AC electrical panel and allow me to run both the heaters and hot water at the same time. or Microwave/coffee pot and hot water.......hummmm Probably going to need that third CNG bottle I've been wanting anyway.

Think I got the bug, how much are these things?

 

[FastOlson]

When we were rebuilding Bietzpadlin there was an on demand water heater that seemed very promicing but before we got to that point(about 1995) the water heater was condemmed and taken off the market. Too many boaters were dieing from CO poisoning.

True. Insurance companies will not touch you either. Without insurance, no loan (if needed) and very few marinas will allow you to moor, either.
Most Paloma or Hot Wolter propane-fired installations actually worked fine, but a few deaths soured the whole insurance industry on the idea.

 

[Stephen Trapani]

...

Think I got the bug, how much are these things?

You can get them new on ebay for $159:

http://cgi.ebay.com/1-6-gpm-LPG-Ven...862?pt=LH_DefaultDomain_0&hash=item3a5f90e286

 

[txtowman]

coleman on demand unit

I have the coleman unit in that link. its 5 years old and works fantastic.

Not a blasting output, but plenty hot. you can put the pump in a 5 gallon bucket and in 3 seconds have a scalding hot stream of water. I used it as the primary supply for my old rv. Filled the tub and set the pump in the bottom, had a hot tub in 5 minutes. Five gallons goes a long way with this thing. It shuts off when you can barely smell the fumes. long runtimes freeze the 16 oz. bottles. the unit has a rechargeble battery that runs the pump and automatic igniter.

sorry for the ramble but it's truly the best portable hwh I have seen.

 

[Seattle Scott]

I installed one this weekend

I will do a write up. keep in mind on the safty issue, it is only going to be "on" for a couple of minutes at a time, maybe two mintues x2 for a shower. After install i ran it for 8 minutes continuous with the locker lid closed and these was not excessive heat to the underside of the deck, about a foot above the heater. When not in use the solinoid at the propane tank is going to be off, just like when using the stove.

 

[Seattle Scott]

another photo of tankless heater

Its in the cockpit locker of a Hunter 37 cutter - deep locker

 

[Stephen Trapani]

A few questions. How was the performance of the Excel? Since you are sitting in the same body of water I am (...err, not Lake WA, right?) I should get the same temperature as you. What gpm did you set the heater on? Sufficient for a shower? Did you set up a separate propane switch for the water heater or do you have one for the whole system? I am planning on putting it in the cockpit locker also, exactly where my current water heater is.

I look forward to the write up. Feel free to answer my questions there if you like.

 

[Seattle Scott]

Stephen, I sent in a "owner modificaiton article" today. But generally, given a "hand test" under the shower head, I would say just enough water flow and heat to make the thing worthwhile. I ran the heater with the flame on high and the water flow about 50% , so about .6 gal/min, so no blasting shower.

Also see this install http://hunter.sailboatowners.com/in...7&cat_id=28&aid=7433&page=article&mn=33_77-83

 

[Stephen Trapani]

Excel on demand water heater performance

Stephen, I sent in a "owner modificaiton article" today. But generally, given a "hand test" under the shower head, I would say just enough water flow and heat to make the thing worthwhile. I ran the heater with the flame on high and the water flow about 50% , so about .6 gal/min, so no blasting shower.

Sorry, I couldn't find the article you sent in. Also, I noticed that you intended to put the excel after your engine heater. I presume the test you refer to above was on cold water with no added engine heat? I don't suppose anyone with one of these has any temperature measurements? I can put up with lukewarmish showers, but the rest of my "crew" might have problems. At .6 gal/min, is the water too hot to touch? Barely warm? Thank you for any info!

 

[Seattle Scott]

Re: Excel on demand water heater performance

Stephen, I will try to get actual measurements this weekend re flow rate and temp. Yes the hot water tank had cold water ( maybe 50 degree) in it when it was runing thru the tankless heater. I think it takes a day or so for the articles to get posted.

 

[Seattle Scott]

Excel tankless heater 1.6 temp and flow results

Using a thermometer, I determined the following: The water temp supplying the tankless heater was 54 degrees. The full flow rate for cold water was 2.15 gal/min ( kind of odd, since the water pump is a 3 - 4 Gal/min rating); With the flame on highest setting the heater produced 112 degree water at .75 gal/min, at 1.3 gal/min you get 98 degree water, but if the flow is reduced to 1.2 gal/min you get nice 105 degree water which is just right for showering and 1.2 gal/min is a nice frugal flow rate.

The tankless heater is in a locker, so I added a passive mushroom vent to get some heat out of the locker. Heat wasn't a problem after running it on high flame for 8 minutes continuous ( about a minute continuous should be normal use) with locker lid closed and the oxigen sensor did not shut the heater off, but the locker draws air from engine compantment and thru the stern lockers and the passive vent was discharging warm air.

 

[Stephen Trapani]

re: Excel tankless heater 1.6 temp and flow results

Using a thermometer, I determined the following: The water temp supplying the tankless heater was 54 degrees. The full flow rate for cold water was 2.15 gal/min ( kind of odd, since the water pump is a 304 Gal.min rating); With the flame on highest setting the heater produced 112 degree water at .75 gal/min, at 1.3 gal/min you get 98 degree water, but if the flow is reduced to 1.2 gal/min you get nice 105 degree water which is just right for showering and 1.2 gal/min is a nice frugal flow rate.

The tankless heater is in a locker, so I added a passive mushroom vent to get some heat out of the locker. Heat wasn't a problem after running it on high flame for 8 minutes continuous ( about a minute continuous should be normal use) with locker lid closed and the oxigen sensor did not shut the heater off, but the locker draws air from engine compantment and thru the stern lockers and the passive vent was discharging warm air.

Hey thanks Scott! Terrific reporting. I now can see no reason not to replace my electric with this unit and use it as the only water heating element on the boat. The CO and propane detectors in the cabin, plus turning off the propane with the solenoid when not in use should be all the safety needed. Now we can have hot water in the middle of nowhere!

 

[Seattle Scott]

Re: Excel tankless heater 1.6 temp and flow results

Stephen, I would still keep the option of shore power electric water heater, meaning replace your electric tank and add the gas heater. Just my preference.

 

[Stu Jackson]

Stephen, I would still keep the option of shore power electric water heater, meaning replace your electric tank and add the gas heater. Just my preference.

I agree, and here's why. Unless the OP has a hefty solar panel or a generator, the steadily diminishing law of returns on battery charging will require him to go to shoreside power to top off his banks completely on a relatively regular basis. I know, I know, people have been out there cruising for years without ever plugging in. But to extend the life of your banks and to overcome that law of returns, it would be worthwhile to do so anyway, and eventually with use the banks will be drawn down below 50% after a week on the hook or traveling from anchorage to anchorage, especially with a refrigerator (without one, maybe not at all depending on his energy budget).

So, since he will eventually plug in, maybe for an overnight stay in a marina, why use gas when electricity is available? If however he's just gonna plug in for a few hours when doing a fuel up, or going to a store for supplies, then may be not.

With boats, backup, backup, backup is never too bad a thing to have.

Your boat, your choice.

Good luck, great thread.