Heaters

[baldbaby2000]

We've used a heat pal type alcohol heater. I think it's pretty safe but I don't like all the condensation. I assume there is no good solution to the condensation problem unless the combusted gas is vented to the outside. If so, are there compact affodable systems that do this?

[Chip Hindes]

This discussion originally happened a long time ago, though it might even have been before the current Board was instituted.

So Ethanol vapour will explode under a broader range of conditions than Propane.

So why is alcohol considered safer?

There's certainly something else going on here; I speculate that it's because of flash point.

The flash point for denatured alcohol (actually not pure ethanol, but a mixture of ethanol and methanol) is 54F. At "room" temperature and pressure, ethanol it remains mostly liquid. I believe the flammability concentrations for alcohol specified are not easy to attain at room temperature and pressure, and that it has to be heated quite a lot above room temp to make it vaporize to the explosive limit, and that the concentrations necessary to get it to explode almost can't happen by accident.

I've had the single burner Origo alcohol stove in my boat since new and I can testify that it's not that easy to light.

Personally, I've never heard of an alcohol explosion, obviously under the right conditions one is possible.

Propane on the other hand is a completely gaseous at room temperature; the flash point is -156F, and it's therefore very easy to attain the percent concentrations necessary to make it explosive.

BTW, your link on the alcohol is dead, so I couldn't look for myself to see what it says.

[Moe]

I pull explosive limits of propane from web as

2.2%-9% volume (source http://www.puyallupfire.com/lepc/propane.htm )

and Ethanol 3.3-19% volume (source http://www.itcilo.it/actrav/actrav-engl ... /64175.htm )

So Ethanol vapour will explode under a broader range of conditions than Propane.

Another way of looking at those figures is that propane can explode with only 2/3 the amount in the bilge as ethanol.

Besides the flash points, you can pretty much control alcohol evaporation with the stove's slide shutter. The pressure in a propane tank depends on the propane liquid surface area and temperature, but is much higher, and subject to leak, compared to alcohol in a canister. So the probability of getting propane in the bilge is probably higher, especially with a stove that doesn't have a thermocouple, that could accidentally be turned on without being lit.

The links are broke because of the close parenthesis on the end that becomes part of the URL. Try the ones in the quote above, where I've spaced the punctuation away from the URL.
--
Moe

[Catigale]

I was misleading in my post - the explosion limits dont tell the whole story of which is safer.

the flashpoint and the spontaneous combustion point are also important.

Most important for risk assessment is the fact that the vapour pressure of ethanol is much much less than that of propane, so that the likelihood that you will have ethanol vapour around is much less, short of pouring ethanol fuel into the bilge.

Moe is correct - you need less propane to make a bilge bomb.

But if you do get some ethanol in the bilge, it will explode under a wider range of conditions..

[craiglaforce]

Here is a sketch of a heater setup I was fooling around with last year.

http://www.macgregorsailors.com/cgi-bin ... record=486


Here are the photos I took (slightly different configuration shown) I had disassembled the horizontal part with the damper valve needed for a heater when these photos were taken. The reason being that the heater I selected puts out too much heat and is difficult to control. I've also thought about using a coleman propane mantle lantern under the fume hood, but haven't tried it yet.

http://www.macgregorsailors.com/cgi-bin ... record=306

[Duane Dunn, Allegro]

Can't say I'd ever go for such a large vent system on my boat. My kids would kick the top of that vent stack overboard in no time and my wife would complain about the intrusive interior pipe.

It seems the Wallas type system is the ideal one. The combustion takes place in a sealed chamber. The stove is built in flush to the galley and the vent outside is a 1" pipe that is completely below the countertop and only has a very small plate on the side of the boat. No intrusion in the cabin, no exhuast gasses, no condensation.

Their stoves, ovens and heaters can all be vented outside via these small unobtrusive pipes. Bluewater installs their systems using the 1066 vent.
http://www.wallas.fi/index_eng.php?page=2

Maybe it is worth the $800.

Here's their brochure, check out the drawings on page 10.

http://www.wallas.fi/pdf/wallas_england.pdf

[richandlori]

For that price I would just buy a Honda EU2000 generator and plug in a 1500W heater and then have the generator for the annual parade of lights!





Rich

[Greg]

I have always enjoyed winter camping somewhat more than other seasons. I have found that using a candle lantern similar to this one http://www.ucocorp.com/ucocand.htm helps to minimize the moisture accumulation on the tent walls (2 person tent).

During a recent 3 day trip on the Potomac River in southern MD, we used the Origo stove to take off the initial chill and then used my candle lantern- the Mac is a much bigger area than a tent, but I think it did help- plus the candle glow is kinda nice.

I have a few varieties of kerosene lanterns that I now burn oil in- they would probably do a better job than the candle lantern but I haven't tried them yet. Ucocorp also makes a lantern that holds 3 of the 9 hour candles http://www.ucocorp.com/ucolier.htm that sounds like it may be worth a try. The ad says it produces enough heat to warm food and boil a small amount of water.

REI has the single lantern listed for $23.00 and the triple listed for $30.00.

[Rick Mathews]

We bought the Wallas heater when we purchased our 26x. I have been very glad that we spent the money for it. It may seem expensive, but remember, it doubles as your stove when the lid is up. The lid goes down for heater mode, and contains a fan that circulates heat around the cabin quite well. The lid/fan combo also keeps the lid cool to the touch, so you don't have to worry about burns when touching it. It runs on pure 100% mineral spirits, which translates to high grade paint thinner. It takes a long time to burn through a gallon of paint thinner (the tank holds about two gallons) and keeps the cabin toasty warm. There is no open flame in either heater or stove mode, and you don't have to worry about fumes because it is vented to the outside. It doesn't smell as long as you make sure the fuel-feed line remains fairly vertical (so unused fuel drains back into the tank and does not remain in the line). It has a thermostatic control so that you can adjust the heat level to the conditions. My wife and I believe it is one of the best purchases we have ever made for our boat.

[Don T]

Hello:
I thought the main consideration was that alcohol vapor is lighter than air so it will not collect in the bilge. When I went to the boat store I only found one alcohol brand that was lighter. Most blends are heavier.

[Tahoe Jack]

A fellow 26x'er in the Seattle area recently mentioned the Dickinson Heaters sold by WM. Their website is: http://www.dickinsonmarine.com/shop5/ca ... eaters.asp
These are available for solid fuel, propane, and diesel. A bit pricey..but serious btu output...and clearly marine. Anyone else have experience with these?

[jda]

Wow, this was my first post here. Thanks for all of the input!!!

jda

[Catigale]

I thought the main consideration was that alcohol vapor is lighter than air so it will not collect in the bilge. When I went to the boat store I only found one alcohol brand that was lighter. Most blends are heavier.

Methanol (sometimes called wood alcohol) is less dense than air. Ethanol (grain alcohol) is more dense than air.

I dont believe you can use methanol in a stove designed for ethanol.

The relative safety of alcohol vs hydrocarbons stems from the lower probability of having vapours present.

[craiglaforce]

I think the Origo is only allowed to burn Ethanol. agree that the safety aspects are more about the fact that you need a substantial open flame to light it rather than a stray spark, plus it can be put out with water, since alcohol mixes well with water. (I removed my club soda joke since denatured ethanol is poisonous).

Ethanol C2H5OH = 24+6+16 = 46 mw

Methanol CH3OH = 12+4+16 = 32 mw

Air is around 28.95 mw (.7811X28+.0093X40+.2096X32)

Both alcohols are heavier than air.

And alcohol is a hydrocarbon . It has H and C Eh?

[Tripp Gal]

We lived aboard for over 8 years, with half that time here in the PNW. On the liveaboard boat we installed the Newport Diesel heater. Let me provide some history.

1. You have to cut a 4 inch hole in the cabin top and install a stovepipe on top. The stovepipe is removeable which we did for racing but you are still left with a 5" stump sticking out of the deck you have to cover if you take the pipe off.

2. They really recommend at least 6 feet of stove pipe length from the stove up. So that means if you mount it 3 feet up a bulkhead you will need 3 more feet of pipe sticking up past your deck.

3. They need a pressurized tank or gravity to feed the diesel into the heater.

4. You need to install it to a bulkhead with nothing around it and it's recommended you either cover the bulkhead with stainless or tile.

5. Very easy to use, very efficient. That thing on low would run us out of a 35' boat it would get so warm.

Now for forced air:
There are 2 types one is forced air the other is "hydrionic". We are having hydrionic installed as we speak.

Forced air units tend to be noisy inside but the unit is simple to install as the burner and everything is right in one unit. You will need at least 2 interior vents cut and the hose is 3.5" air duct hose from the burner to the vents. You will also need a 42mm vent hole cut for the vent tube mounted to your transom.

Hydrionic: The burner unit is housed with a water exchanger that pushes water through 3/4" radiator hose run through the boat. the vents are basically red dots with a fan behind them. While the water is flowing through the radiator hose it warms the hose and keeps moisture down as it runs through cabinets and cubbies on the boat. Holes are smaller to cut in this system but you will still need at 42mm vent hole cut into your transom. Now the cool part, you can set this system up to be your hot water heater as well, and you can set it up to run off your diesel engine so while underway you don't have to run the forced air burner.

There is a system you can use that is popular for I/O's and inboards that runs forced air heat while the engine is going. That's great but we like sailing and anchoring out in relative quiet so it defeats the purpose when you have to run your engine to get cabin heat.

I have always used unpressurized alcohol in the boats for cooking and while it's fine for that I really hate that smell of the burning alcohol that the Origo heater and stoves give off.