Off grid heating

ghostlymoron said:
Just out of interest for candle powered fanatics. This video has some measurement of output. Sort of shows that the laws of physics have to hold good. Flower Pot Heater - The reality: http://youtu.be/zCAfAT9MVrY
As someone has pointed out, burning hydrocarbons will produce water vapour which will make a boat (or any space) damp.
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not read the comments on the film then I take it

he was trying to heat rather a large room

as for the moisture given off

how much moisture is there in four tealights?

youboysisfunni

I take it that I only imagine that I am sailing in the winter without an eber

D
 
That flowerpot/tea-light video was woeful. I didn't need persuading that candle-warmed terracotta isn't the answer to winter comfort afloat, but that chap waffled for so long, I was wondering whether the conclusion would be pro or anti.

Threads about heating, especially one begun at this time of year, always dredge up familiar loyalties and dislikes. Here are mine...

I can't see the point of anything which, unvented, burns the same air we breathe inside the cabin while producing much deadlier exhalations than we do, plus lots of moisture.

I couldn't stand a heater whose noise upset or annoyed those aboard, or indeed persons on boats nearby. And, I'd rather there wasn't a significant fire risk.

I can see considerable appeal in a solid fuel stove, despite the mess they must cause...

...but what I can't fathom, is regarding heaters which do their burning outside the cabin, while ducting clean, dry, totally safe heat into the cabin, or cycling the warmed cabin air repeatedly through the same heating process. Why aren't these aren't more popular? How hard can it be to house something like a Propex heater in a ventilated cockpit locker, where noise-nuisance is minimal and potentially dangerous fumes just get blown away?
 
Most of these responses seem to be missing the point. The OP is not looking for heating when he is using the boat, but a way of keeping the temperature up to reduce dampness when the boat is laid up and not in use. If he had electricity then the usual solution would be tube heaters, perhaps on a timer. However, without electricity there is no safe alternative.

The suggestions to strip the boat, open all lockers and ensure adequate ventilation - plus stopping water getting in is the best you can do, and is effective.
 
dylanwinter said:
how much moisture is there in four tealights?
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Assuming an approx formula for the wax of C25H52
and a density of 900kg/m3

Given the dimensions are 38mm diam x 15mm high

A little bit of elementary schoolboy science and simple arithmetic gives the answer that:

approx 80g water will be produced by burning 4 tea lights
 
VicS said:
A little bit of elementary schoolboy science and simple arithmetic gives the answer that: approx 80g water will be produced by burning 4 tea lights
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Surely that's not right, Vic? 80g of water will be more than the total weight of the candles! I tested it. Well, you did say schoolboy science. 80ml of water, measured carefully...

4tealightsweighlessthan80gofwater_zpsb36f3b6d.jpg
[/IMG]
 
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the rule of thumb (because candle wax varies so much in composition) is that for every kg of mass burnt, then 1 L of water is produced.


I'd really love those who espouse candle heating as a means of warming a cabin, to put their nose over the top of the flowerpots and inhale deeply for a while, maybe for an hour so. The resultant brain and lung damage would prevent these silly and dangerous posts from recurring and misleading innocent people.
 
dancrane said:
That flowerpot/tea-light video was woeful. I didn't need persuading that candle-warmed terracotta isn't the answer to winter comfort afloat, but that chap waffled for so long, I was wondering whether the conclusion would be pro or anti.
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I agree that the video was not the best evidence that could have been done but at least he did make some effort to measure the heat coming off the 'heater' by warming a pan of water. Perhaps a better test could be devised. It's just clear to me that, even with 100% efficiency, you can't release more heat to the space than the nitelites can produce. Some of the aficionados now seem to be backing off a bit and saying they're just handwarmers rather than spaceheaters - I can accept that but think that a hotwater bottle would be more use for that.
 
Tranona said:
Most of these responses seem to be missing the point. The OP is not looking for heating when he is using the boat, but a way of keeping the temperature up to reduce dampness when the boat is laid up and not in use. If he had electricity then the usual solution would be tube heaters, perhaps on a timer. However, without electricity there is no safe alternative.

The suggestions to strip the boat, open all lockers and ensure adequate ventilation - plus stopping water getting in is the best you can do, and is effective.
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We didn't bother heating the boat during the winter "layup" afloat - well, not whilst we weren't onboard - it's just wasted heat! We did run an electric dehumidifier - although this collected less and less water as it got cooler (because cold air doesn't hold as much moisture as warm). One of the problems we had (and hence the dehumidifier) was that the boat warmed up a fair amount when it was sunny, then cooled down once again. Being an AWB it wasn't easy to get a lot of ventilation through when we weren't onboard whilst keeping the boat secure.

I think the OP is doing the right thing though - plenty of ventilation, open up the lockers for air to circulate and heat it when he visits - whether crystals would help or not I'm not sure but it certainly won't hurt ...
 
dancrane said:
Surely that's not right, Vic? 80g of water will be more than the total weight of the candles! I tested it. Well, you did say schoolboy science. 80ml of water, measured carefully...
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Are you a medievalist? They believed in Phlogiston as well.

I'm not a real bonefide chemist, but even I know (as do you) that water is H2O.

The O comes from the air and has an atomic weight of 16. The Hydrogen comes from the candle with an atomic weight of 1, so each gram of H produces 9 grams of water, the extra 8 grams coming from the air. Hence the scales thing is a nonsense.
 
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sarabande said:
the rule of thumb (because candle wax varies so much in composition) is that for every kg of mass burnt, then 1 L of water is produced.
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Are you sure? So, there's one litre (which is also one kilo weight) of water, in one kilo of wax? Is wax nothing but water?

Perhaps early desert explorers should have taken boxes of candles as water-sources, which could also provide light.

Aside from the heating issue, I'd like to understand about wax and water, if anyone can clarify?
 
jdc said:
The O comes from the air and has an atomic weight of 16. The Hydrogen comes from the candle with an atomic weight of 1, so each gram of H produces 9 grams of water, the extra 8 grams coming from the air.
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I believe you - but I won't pretend I understand! Never mind. Thanks! :encouragement:
 
dancrane said:
Surely that's not right, Vic? 80g of water will be more than the total weight of the candles! I tested it. Well, you did say schoolboy science. 80ml of water, measured carefully...
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Do the maths. I have said what input values ( molecular formula of the wax, density and dimensions of the Ikea tea lights ) I used .
 
VicS said:
Do the maths. I have said what input values ( molecular formula of the wax, density and dimensions of the Ikea tea lights ) I used .
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Apologies, Vic - it's now staringly obvious how little I understand of the chemistry involved.

Interesting idea though - that it's possible to make water, using gases. Although, probably only interesting until someone has explained the scientific limitations of the idea. :rolleyes:
 
VicS said:
Assuming an approx formula for the wax of C25H52
and a density of 900kg/m3

Given the dimensions are 38mm diam x 15mm high

A little bit of elementary schoolboy science and simple arithmetic gives the answer that:

approx 80g water will be produced by burning 4 tea lights
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a tiny amount then

most of which will be vented out of the hatch you have open

listen up chaps

it works

try it

then knock it

as for those who say it is dangerous

really lads - HTFU - best not leave the house

D
 
dancrane said:
I believe you - but I won't pretend I understand! Never mind. Thanks! :encouragement:
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You leant the basics of this in year 8 and then in more depth in year 10 or 11

the combustion of wax can be represented by

C25H52 + 38O2 -> 25CO2 + 26H2O​

which means that 1 mol of wax produces 26 mols of water

the relative atomic masses are: H 1; C 12; O 16

So the relative molecular masses are wax 352 and water 18

therefore 352 g wax produces 26 x 18 = 468g water

or 1000g wax produces approx 1330g water

or 15g ( the approx mass of an Ikea tea light) wax produces approx 20g water.
 
dancrane said:
Surely that's not right, Vic? 80g of water will be more than the total weight of the candles! I tested it. Well, you did say schoolboy science. 80ml of water, measured carefully...

4tealightsweighlessthan80gofwater_zpsb36f3b6d.jpg
[/IMG]
Click to expand...


Yes but the combustion products include the weight of the oxygen from the air that supports burning.

The general formula is something like:

CnH(2n+2) + (2n+1)O2 -> nCO2 + (n+1)H20


That roughly works out that 14 grams of hydrocarbon combines with 64 grams of oxygen to produce 46 grams of CO2 plus 18 grams of water.

In other words, you really do get more water than the original weight of fuel, but most of the weight of the CO2 and H2O is in the oxygen from the air.
 
of course you lose some of it - just as you do when cooking or burning oil lamps in boats

the best sort of heating on any boat is plugging into the mains and using a fan heater

the alternative for the well funded is, of course, to use eber/web and join in the everlasting threads on why they won't start.

Candles are a cheap and cheerful solution used by an old bloke who does a fair amount of winter sailing... who wears a lot of warm clothing as opposed sitting around the cabin of a 35 footer wearing nowt but his satin lounge keks

certainly the flower pots do not increase the heat outbout but they do aid convection - just like the electric convector heater in my bathroom. The element is in a tall box that increases air flow and helps to spread the warmth around the room.

The old flower pot trick will never be as effective as effective as a £2000 heating system and never will be

but fitting a heating system er that costs more than the boat makes very little sense to me.

It seems a lot safer than a parafin heater (which is the way our house was heated when I was a nipper) - it certainly smells a lot better. I get no blackening of the inside of the flower pots so I assume that I am getting a pretty clean burn from the tealights.

I have tried to make my Argos co and co2 detector go off using it on the boat - and have failed

I think that four small candle flames really are not much of a risk to human health but they are enough to stop you having to retreat to the sleeping bag as soon as it gets dark

however.... if you think it is innefective and too dangerous then carry on thinking that rather than finding out for yourselves

It is a classic forum response

- you MUST spend as much as I do on safety and comfort while sailing otherwise you are a fool who is certain to meet a well deserved death

that attitude extends to Dubs, life rafts, £500 offshore sailing suits, epirbs, DSMs, bruce anchors, radar, ASMs and rocket propelled granades


please feel free to post all sorts of "I told you so" comments when I am found dead in my boat through tealight poisoning, cold feet, anchor dragging, failure to contact the emergency services, run down by a ship, attacked by pirates.

Until i started posting on these forums I had no idea that I was such a deluded foolhardy sort of bloke. Driving to the boat is much more dangerous than anything I can dream up on on the water


yours


Dangerous Dyl
 
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