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Old 21-02-2008, 07:52   #61
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Originally Posted by Strygaldwir View Post
Purchased a propane indoor gas heater with auto shut-off features. Heats up the boat very nicely, no installation hassles, ducting, routing, wiring etc...
Similar question to Mark, above:

Is that a Mr Heater propane heater?

I looked at those, but somehow was nervous to trust my life to its low oxygen sensor (made in China).

Mark, they really do give off no (or extremely little) CO, but in the process give off a ton of moist, hot air. Bad for condensation. Still, I had considered them, and may have got one if it wasn't for having to rely on the "low oxygen sensor" to shut the unit down after it burns through all of your air.

MR. HEATER - America's Most Popular Brand of Portable Heaters
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Old 21-02-2008, 16:25   #62
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Quote:
Originally Posted by ssullivan View Post
Similar question to Mark, above:

Is that a Mr Heater propane heater?

I looked at those, but somehow was nervous to trust my life to its low oxygen sensor (made in China).

Mark, they really do give off no (or extremely little) CO, but in the process give off a ton of moist, hot air. Bad for condensation. Still, I had considered them, and may have got one if it wasn't for having to rely on the "low oxygen sensor" to shut the unit down after it burns through all of your air.

MR. HEATER - America's Most Popular Brand of Portable Heaters
You could always install a stand alone oxygen alarm with gas shutoff to the bottles. May be a good idea in any case as a backup just in case with any form of air/water heating.

Mike
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Old 21-02-2008, 16:57   #63
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Yes, it is a Mr. Heater. You can always keep a hatch cracked. I have Carbon Monoxide alarms on the boat. Might not work with excessive amounts of carbon Dioxide. If what they told me in my diving classes is true, the body is rather aware of excessive amounts and build up of Carbon Dioxide. Probably wake you up! Any way, after watching it for several weeks, I got confident enough to keep it on at night. Still here so far!
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Old 22-02-2008, 03:39   #64
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... If what they told me in my diving classes is true, the body is rather aware of excessive amounts and build up of Carbon Dioxide. Probably wake you up! Any way, after watching it for several weeks, I got confident enough to keep it on at night. Still here so far!
Elevated ambient levels of Carbon Dioxide (CO2) and/or Carbon Monoxide will NOT wake you up!
You are much more likely to die in your sleep.


When any fire burns, in an enclosed space, the amount of oxygen (O2) available gradually decreases. At the same time the amount of carbon dioxide (CO2) increases. As the amounts of these two gases change, this increasingly causes the combustion process to alter from one of complete combustion, to one of incomplete combustion. This results in the release of increasing amounts of carbon monoxide (CO).

Any heating system that puts out enough CO2 to be toxic will likely kill you by CO first.
CO2 deaths generally occur only in exotic places like submarines and spacecraft, where absorbers fail, but O2 supplies don't.
It would have happened in Apollo 13, for instance, if not for some quick fixes with duct tape and the like to get one kind of LiOH CO2 absorber mated with another system.

Humans don't have good anoxia/hypoxia sensors, and you can breathe into a closed circuit which takes out the CO2 until you pass out from hypoxia, without much discomfort at all. On the other hand, in a submarine or someplace where CO2 is building up but there's plenty of oxygen, it's intensely uncomfortable.


STAGES OF HYPOXIA

1. INDIFFERENT STAGE
The only adverse effect is on dark adaptation.

2. COMPENSATORY STAGE
Physiological compensations provide some defense against hypoxia so that the effects are reduced unless the exposure is prolonged or unless exercise is undertaken. Respiration may increase in depth or slightly in rate, and the pulse rate, the systolic blood pressure, the rate of circulation, and the cardiac output increases.

3. DISTURBANCE STAGE
In this stage the physiological compensations do not provide adequate oxygen for the tissues.

Subjective symptoms may include: fatigue, lassitude (state of exhaustion), somnolence (drowsiness, sleepiness), dizziness, headache, breathlessness, and euphoria.

Objective symptoms include:
- Special Senses – Both the peripheral and central vision are impaired and visual acuity is diminished.
- Extraocular muscles are weak and incoordinate – Touch and pain are diminished or lost. Hearing is one of the last senses to be impaired or lost.
- Mental Processes – Intellectual impairment is an early sign and makes it improbable for the individual to comprehend his own disability. Thinking is slow. Calculations are unreliable. Memory is faulty. Judgment is poor. Reaction time is delayed.
- Personality Traits – There may be a release of basic personality traits and emotions as with alcoholic intoxication (euphoria, elation, pugnaciousness, overconfidence, or moroseness).
- Hyperventilation Syndrome – Over-breathing due to excitement or stress. Cyanosis – Blue discoloration of the skin.

4. Critical Stage

In the critical stage consciousness is lost. Death follows shortly.

BTW: Carbon monoxide has an affinity for the blood 20 times greater than oxygen. Given a choice between carbon monoxide and oxygen, the hemoglobin will choose the carbon monoxide. A smoker experiences a comparative physiologic altitude of 3,000 to 8,000 feet while at sea level.
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Old 22-02-2008, 07:04   #65
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Yes, Carbon monoxide is VERY dangerous!!!! That's why we have CO sensors and alarms in ALL the sleeping cabins. The most incideous part is you don't even now your being poisoned. ALL boats should have CO sensors, regardless of type of propolusion, heating or cooking systems. You can be poisoned by emissions from the boat next door!

Carbon dioxide is not as dangerous as carbon monoxide, but it too is a hazard. The sensors on the heater state that it is safe for indoor usage. It states that it will shut off when the level of carbon dioxide gets too high. We have hatches that have a vent setting on them, so I still keep one in our cabin slightly open when we are sleeping.

I wish the CO detectors would sense carbon dioxide, but I dont count on them doing so. But in anycase I'll always suggest that anyone excersice the dilligence that they feel is appropriate for them and act in accordance with what they feel is appropriate!!!

The real answer is never put your boat where it is cold enough to need a heater! at least that's what my wife says!!!
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Old 22-02-2008, 07:45   #66
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Strygaldwir,

What heater did you buy? Are there really indoor propane heaters? I thought all of them had CO potential issues - and even the ones rated indoor had warnings to not use in enclosed spaces.

Mark
This is my first winter as a liveaboard. I initially bought a higher-priced electric space heater (oil-filled coils, etc.) from Home Depot. It lasted about a month and quit. I then tried a cheaper (1/2 to 1/3 the cost) "Pattan" quartz heater and it has worked brilliantly - I now have two of them in the main cabin, set on timers. They come on about an hour before I arrive in the evening and shut off when I leave. It's been a very satisfactory arrangement.

I have considered one of those propane heaters as a back up against the possibility of power failure at the marina (it has failed once this winter, but only briefly). The CO2 thing scares me though.
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Old 22-02-2008, 08:14   #67
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Originally Posted by Strygaldwir View Post
Yes, Carbon monoxide is VERY dangerous!!!! That's why we have CO sensors and alarms in ALL the sleeping cabins. The most incideous part is you don't even now your being poisoned. ALL boats should have CO sensors, regardless of type of propolusion, heating or cooking systems. You can be poisoned by emissions from the boat next door!

Carbon dioxide is not as dangerous as carbon monoxide, but it too is a hazard. The sensors on the heater state that it is safe for indoor usage. It states that it will shut off when the level of carbon dioxide gets too high. We have hatches that have a vent setting on them, so I still keep one in our cabin slightly open when we are sleeping.

I wish the CO detectors would sense carbon dioxide, but I dont count on them doing so. But in anycase I'll always suggest that anyone excersice the dilligence that they feel is appropriate for them and act in accordance with what they feel is appropriate!!!

The real answer is never put your boat where it is cold enough to need a heater! at least that's what my wife says!!!
Reading the label on Mr Heater, I noticed that the shut off mechanism is not for CO or CO2, but for O2. When the O2 level gets too low, it shuts off the heater. (correct me if I'm wrong)

I just watned to clarify this. Apparently, these special catalytic elemets in the heater burn so efficently, they release heat and water vapor for the most part and almost no CO. I think they do release some CO2, however.

But the sensor detects O2 levels and shuts off the flame if there isn't enough O2 left to continue supporting life. It's that sensor that made me nervous. I have a hard time trusting my life (and especially my wife's) to that little sensor.

A separate sensor as backup does sound like a good idea to me, but then again, I'll just stick with my 29,000 BTU wood stove.

No CO, no CO2, and an ample supply of fresh air (sucked in due to the draft of the chimney creating a negative pressure in the cabin)
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Old 22-02-2008, 08:27   #68
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Doesn't a stove give you the same problem? Namely, consumption of available Oxygen? Don't you have to vent to replace the o2?
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Old 22-02-2008, 08:43   #69
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Doesn't a stove give you the same problem? Namely, consumption of available Oxygen? Don't you have to vent to replace the o2?
No, actually they do not.

It's hard to describe in words, but I'll try:

In order for your fire to be lit and working, a hot combination of smoke/air/CO/CO2/heat must be going up the chimney.

As this hot waste air travels up the chimney, it leaves a negative pressure in the wood stove. (picture it like the chimney is a big straw and someone is sucking on the end of it)

So as this air rises up the chimney and creates negative pressure inside the stove, there becomes a need for the stove to pull air into itself to equalize the pressure.

It pulls its air in through the vents on the stove. It sucks air into itself (to replace the air that went up the chimney) through the stove vents. The stove operator controls these vents to adjust how much air gets into the stove and ultimate goes up the chimney.

Now, in the same way the chimney sucked air out of the inside of the stove, the stove itself (through the vent) is sucking air out of the cabin/room, which then goes into the stove, burns up with the wood and then is sucked up the chimney.

So, the basic principle is that a natural draft stove (one that has a chimney) is constantly sucking air *in*, so there is never a time that the fire inside the stove is involved with the air in your cabin/room. CO and CO2 cannot escape the stove, because the airflow is *into* the stove, and up the chimney.

Where does all the air the stove is sucking in from the room come from? Cracks, openings, hawsepipes, spaces between companionway slats, etc... So as to a supply of fresh O2, if your fire is lit and your stove isn't backing up (which it never does if you installed the chimney properly), you have a forced supply of fresh O2, owing to the fact that air has to come in *somewhere* to replace the air going up the chimney.

In fact, the amount of air coming into a place that has a natural draft stove running is precisely equal to the amount of smoke you see going out the chimney. You just don't have to open up hatches and stuff because it all happens in one direction. (waste air out the chimney, good air in the cracks)

With the propane heater, you are opening a hatch to try and let some bad air out at the same time you are trying to let some good air in. This makes a place "drafty."

Hope that helps. There are a lot of people out ther who don't understand this stuff at all - the majority, I think.

When I pulled into a campground with the "land boat" RV I built and the guy found out I had a wood stove, he said, "have you ever stayed in that thing overnight?" I said, yeah... since October. He said, "well, you have to be real careful you don't suffocate and die in there with the wood stove." I basically, said, "Duh.... ! " The guy has a wood stove in his house too, and uses it 100% of the winter for heat. However, he still didn't understand how one works!
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Old 22-02-2008, 10:52   #70
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Sean, I think you did a good job explaining it. As Strygaldwir says you do need vents to let fresh air in, but as you have stated most boat have enough cracks to let air in. If you have negative pressure in the cabin you will get reverse air flow (air coming down the chimney pipe).

Check out this link.

http://www.woodstove.com/guidepdfs/C...ackpuffing.pdf

I am a big fan of heating with wood.

Paul
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Old 23-02-2008, 11:11   #71
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Pardon my presumption, but absent your specification, Iím forced to make certain assumptions about your intended meanings. I certainly didnít expect you to be speaking about halyard snap-shackles (17-4PH); but the common Bow or D shackle (as ďavailable in the rope section of Home DepotĒ), which might be used with an anchor rode.
Avesta makes a product called Moly Drop which can identify Stainless 316. A lot of 304 grade stuff shows up as 'marine grade' - but sadly it isn't!

I still wouldn't use unbranded stuff for any critical system.
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Old 23-02-2008, 11:20   #72
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When I pulled into a campground with the "land boat" RV I built and the guy found out I had a wood stove, he said, "have you ever stayed in that thing overnight?" I said, yeah... since October. He said, "well, you have to be real careful you don't suffocate and die in there with the wood stove." I basically, said, "Duh.... ! " The guy has a wood stove in his house too, and uses it 100% of the winter for heat. However, he still didn't understand how one works!
Sean,

The best and safest solution is to actually have a dedicated vent which feeds external air directly to the stove. By 'feeding' the combustion with cabin air you're actually creating a draft which is sucking your warm, humidified cabin air into the combustion and up the chimney!!

Plus, this means that the combustion isn't potentially sucking oxygen out of the living space.
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Old 23-02-2008, 12:51   #73
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Sean,

The best and safest solution is to actually have a dedicated vent which feeds external air directly to the stove. By 'feeding' the combustion with cabin air you're actually creating a draft which is sucking your warm, humidified cabin air into the combustion and up the chimney!!

Plus, this means that the combustion isn't potentially sucking oxygen out of the living space.
I strongly disagree.

You want to feed your fire with cabin air, so you always have nice, fresh, dry air in the cabin. See... when you live in high lattitudes, humid cabin air is your worst enemy. You develop condensation everywhere - and when it's really cold, that condensation can turn to frost in spots.

Only by feeding the combustion with your humidified cabin air, do you keep the humidity down, and keep the place dry. You *want* to get rid of humidity and stale cabin air, not keep it!

I'm sorry. Your last sentence makes no sense. You aren't understanding how a wood stove works. Reread what I wrote about the stove always sucking air in. It is physically impossible for your last sentence to happen.
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Old 23-02-2008, 13:34   #74
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Sean I tend to agree with you about pulling out the cabin air thereby letting fresh air in. I suppose if the cabin was airtight you could have problems but in the real world an airtight cabin is unlikely, besides you could always crack a hatch open.
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Old 24-02-2008, 12:40   #75
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I strongly disagree.

You want to feed your fire with cabin air, so you always have nice, fresh, dry air in the cabin. See... when you live in high lattitudes, humid cabin air is your worst enemy. You develop condensation everywhere - and when it's really cold, that condensation can turn to frost in spots.

Only by feeding the combustion with your humidified cabin air, do you keep the humidity down, and keep the place dry. You *want* to get rid of humidity and stale cabin air, not keep it!

I'm sorry. Your last sentence makes no sense. You aren't understanding how a wood stove works. Reread what I wrote about the stove always sucking air in. It is physically impossible for your last sentence to happen.
Sean, I designed and built schools on Hudsons Bay that were solely heated with stoves. I know how stoves work.

If your goal is to heat then you should to feed the fire with a dedicated outside air source. This allows the stove to work at maximum efficiency - you can still adjust the mix of inside/outside air supply if your goal is to control humidity.

To address your other concern - fresh cabin air - you open a window or dorade vent.
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