Really small heater for 18ft boat

chrisbitz said:
...on an 18ft boat, where would you put the chimney? Where would you put the heater for that matter too? :-)
Click to expand...

Chimney? Who said anything about needing a chimney? :confused: I'm thinking serious miniaturisation for a tiny boat...

...let's think of a £10 camp-stove (about as much as I know about mobile heating). Let's put the stove in a fire-proofed, insulated crate with an aluminium frame (we'll aim to keep weight down)...and above the burner, we put some form of heat-conductive manifold...

...through which, fresh air (ducted from upwind) can be blown by a fan (powered by a battery, inside the crate)...so, when the gas is lit and the motor turns the fan, the flame heats the copper-bottomed manifold, and the heated fresh air inside blows down a hose...

...into the sealed cabin. In use, the heater sits overnight on the cockpit floor. It's only 45cm square x 25cm high after all...weighs around 8kgs with a decent propane supply? You'd only need to put a re-sealable 3" hole in your companionway hatch, for the hot-air duct...

...a vent ensures the burner isn't smothered, and alarms can alert the user to imminent overheat/explosion-risk, etc...

I'm not even attempting to pretend to have thought it through very carefully...but doesn't a neat little crate, like a tiny "suitcase generator", sound better, more like a 21st century solution to an ancient problem?

Presently, we mull over fire-hazards & condensation, like a lot of Edwardian motorists discussing carb trouble & oiled plugs!

I'm mainly amazed that "suitcase heaters" aren't already out there, quietly & safely warming small yachts' cabins, from outside.
 
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Thanks for that, Jimmcgee...replace the wood-stove with a portable propane-burner, and that's really what I had in mind...

...it really hadn't occurred to me I could even dispense with the circulation-motor! But the principle seems to stand up well...if one built a very compact water-heater or air-heater, and piped the heat into the cabin, the deadly business of combustion would stay outside.

I can't decide whether I'm more excited or frustrated by the fact that almost everyone else seems to have overlooked this possibility! I'd mainly been thinking some sort of cabin-matting, like under-floor heaters use, connected to the propane water-boiler outside...

underfloor_heating.jpg


...but I don't honestly have a clue if it's equally easy to heat and pump air the short distance that would be required.

Doubtless there's lots of dangerous fun ahead, creating "The Crane-ulator". But one thing I do know, I won't be relying on tea-lights! :)
 
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dancrane said:
Indeed? Then, why are they priced around thrice what I intend my next boat to cost? :eek: :D

Surely their use of the science - which must be very simple if I've the least grasp on it - can be downsized to run off a dinky propane cylinder, & draw just enough amps from a sub-20-footer's battery (or integral cell) to blow steady heat into a cabin the size of a tent?

The names Eberspacher and Webasto seem often to ring bells of wishfulness, downcast humility, furious dissatisfaction and copious sheer envy, because they're so costly...but is the action they perform so impossible to replicate cheaply, given a little technical understanding?
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Just how much do you want to pay?

Here's a kit for a brand new small Eber for £750 - but it does need the marine exhaust adding.

http://www.ebay.co.uk/itm/EBERSPACH...ervan_Caravan_Accessories&hash=item4d05afebb5

Or this one is £678 with a silencer on the exhaust as well. (I don't consider that my Eber is noisy and it hasn't got a silencer - but it was fitted EXACTLY according the the manufacturers instructions...)

http://www.ebay.co.uk/itm/EBERSPACH...ervan_Caravan_Accessories&hash=item4d05afebb5

The Eber/Webasto etc do exactly what you are describing. A small burner heating air up that is ducted into the cabin of the boat. They do water ones as well if you want the radiators - but that is rather involved for a very small boat?
 
dancrane said:
Chimney? Who said anything about needing a chimney? :confused: I'm thinking serious miniaturisation for a tiny boat...

...let's think of a £10 camp-stove (about as much as I know about mobile heating). Let's put the stove in a fire-proofed, insulated crate with an aluminium frame (we'll aim to keep weight down)...and above the burner, we put some form of heat-conductive manifold...

...through which, fresh air (ducted from upwind) can be blown by a fan (powered by a battery, inside the crate)...so, when the gas is lit and the motor turns the fan, the flame heats the copper-bottomed manifold, and the heated fresh air inside blows down a hose...

...into the sealed cabin. In use, the heater sits overnight on the cockpit floor. It's only 45cm square x 25cm high after all...weighs around 8kgs with a decent propane supply? You'd only need to put a re-sealable 3" hole in your companionway hatch, for the hot-air duct...

...a vent ensures the burner isn't smothered, and alarms can alert the user to imminent overheat/explosion-risk, etc...

I'm not even attempting to pretend to have thought it through very carefully...but doesn't a neat little crate, like a tiny "suitcase generator", sound better, more like a 21st century solution to an ancient problem?

Presently, we mull over fire-hazards & condensation, like a lot of Edwardian motorists discussing carb trouble & oiled plugs!

I'm mainly amazed that "suitcase heaters" aren't already out there, quietly & safely warming small yachts' cabins, from outside.
Click to expand...

Its a great idea that I have also also been mulling over after seeing the prices of the boat heaters on ebay. I was thinking about basing it around a burner from a "table top" patio heater. The burner would go inside a finned box and air forced past it with a fan and through ducting into the cabin.

jono
 
Hmm...sounds logical, Jono. What I can't easily believe, is that some company somewhere isn't already building them!

For tents, caravans and a great many yachtsmen, a simple, lightweight, compact heater which could be properly mobile, would appeal.
 
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The kit-version of Eberspacher's solution to the problem (below) costs £750, which I concede is less than I imagined:

View attachment 21835

(Although, looking at it, I'm still wondering quite where all that money goes...:eek:) Thanks for the pic Mr Morris. :)

But...do all ye who huddle around tea-lights & damp-distributing gas burners (which, perversely, require you to open a hatch) honestly believe a small burner/blower that can be parked outside during use, wouldn't be a practicable improvement on the present options?

Some clever Chinese manufacturing crew could turn them out cheaply and quickly...look at the way those very cheap square camping stoves have completely monopolised the market in a few short years, so that now, no-one uses anything else. Watch this space... :rolleyes:
 
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Rigger Mortice said:
...Propex heaters. Starting price around £450.
Click to expand...

Okay, getting warmer, if you'll pardon the pun. Still...what proportion of a sub-20ft-yacht's budget does £450 represent?

I'm hugely in favour of spending money to extend one's season - because having a boat ashore six months p/a is rotten value.

But I'm not clear why a finished, compact 'outdoor' heater which simply ducts dry, clean heat to a sealed cabin, has to cost more than, say, treble the price of its components. Shows how little I know of commerce & industry. But I'm interested in what's practically possible.

Anybody agree with me, that such a reassuringly safe system (to beat damp/monoxide-emitting flame/catalyst heaters discussed here) would be extremely tempting to budget-boaters, if it sold for, eg £125? I'm determined to build a prototype, if only for my own use! :)
 
Got me thinking.
You know how most air on units have an inside bit and an outside bit , connected via pipes for the refrigerant etc.

If you could combine the cheap but damp and poisonous bit outside with a radiator inside you could have a portable safe system.
Using water as the transfer media.
Would need a small circulation pump.
12v power requirement
The outside bit is a conventional Burner heating water via a heat exchanger.

Such a thing does not exist but if one did I would pay about £250 for one.
 
Nice idea, Jakeroyd. Whilst I've only a superficial understanding of what you're describing, the intrinsic outdoor/indoor element seems to me to be a quantum leap forward from the danger and inconvenience which most forumites apparently accept as their only option.

I believe early motor-cars didn't have heaters. Possibly their winter passengers would have welcomed a naked flame inside? :rolleyes: But having made the jump to ducting engine heat to the cabin, who would favour such a backward solution as a naked flame, there?

In 2012, shouldn't there be a portable, efficient, compact, weatherproof, lightweight system which at a stroke, eliminates the temptation to bring naked flames inside tents, vans and boats? I don't believe it needs to be a permanent, intrusive fixture, or cost a packet.
 
dancrane said:
Indeed? Then, why are they priced around thrice what I intend my next boat to cost? :eek: :D

Surely their use of the science - which must be very simple if I've the least grasp on it - can be downsized to run off a dinky propane cylinder, & draw just enough amps from a sub-20-footer's battery (or integral cell) to blow steady heat into a cabin the size of a tent?

The names Eberspacher and Webasto seem often to ring bells of wishfulness, downcast humility, furious dissatisfaction and copious sheer envy, because they're so costly...but is the action they perform so impossible to replicate cheaply, given a little technical understanding?
Click to expand...

Well, that's the problem. But as far as I can see, a solution that does what you describe will cost what they do, at least if it does it safely and efficently. I don't really see why Eberspachers and so on are so dear; after all, they are standard equipment on lorry cabs, and that's a FAR bigger market than we are! And I am given to understand that they can be bought secondhand or grey market a LOT cheaper than the new price.

Someone once pointed out to me that the cheapest solution for a boat in a marina is an electric fan heater - it will be cheaper to run than anything else, even at Marina electricty mark-ups. Safety wise, I've got one that switches off it is moved off its base, and of course, no electrical heater produces CO. But that doesn't help a lot of people using moorings or anchoring frequently.
 
Good idea

jakeroyd said:
Got me thinking.
You know how most air on units have an inside bit and an outside bit , connected via pipes for the refrigerant etc.

If you could combine the cheap but damp and poisonous bit outside with a radiator inside you could have a portable safe system.
Using water as the transfer media.
Would need a small circulation pump.
12v power requirement
The outside bit is a conventional Burner heating water via a heat exchanger.

Such a thing does not exist but if one did I would pay about £250 for one.
Click to expand...

Excellent idea to use water to transfer the heat. The problem with forced air is that any leak between the exhaust and the fresh air could be disastrous.

Jono
 
jono_howlett said:
Excellent idea to use water to transfer the heat. The problem with forced air is that any leak between the exhaust and the fresh air could be disastrous.

Jono
Click to expand...

That's how the top-end "Hydronic" range of Eberspachers work. They cost abour 2-3 times what the "Airtronic" range do, but they do provide hot water as well as heating!

Seriously, there is a major conflict here between what is needed and what it costs to provide. And it isn't easy to address; the market is a) tiny and b) not able to meet the costs of development. And the product isn't simple; it is a safety critical item that MUST fail-safe. That's why lorry cab heaters - and that's what Eberspachers and Webasto etc. are - are the best option right now; we're a tiny add-on to a much larger market. Anything specifically developed for boats will cost a LOT more, because the market is smaller, and the development and tooling costs have to be spread over a very small market.

By the way, if you look at what a modern domestic hot-water boiler costs, things like Eberspachers and so on start to look a lot cheaper :)

So, if you want inexpensive, the low-tech solutions are probably best, for all their drawbacks. Safety-wise, I have to say that Dylans plate of tea-lights seems to be about the best; I'd suggest putting the plate in a biscuit-tin lid full of water as an additional fire precaution!

From my early boating days, I must admit that of all the solutions suggested, I'd tend to go for a pressure lantern; lots of light and nice and warm. But that's mainly nostalgia speaking! No-one has mentioned it, but they do present a tiny extra risk, though - the mantle is made of Thorium Oxide, and Thorium is radioactive, though with a very long half-life. It really isn't a good idea to breathe in dust from a broken mantle!
 
AntarcticPilot said:
Someone once pointed out to me that the cheapest solution for a boat in a marina is an electric fan heater...no electrical heater produces CO. But that doesn't help a lot of people using moorings or anchoring frequently.
Click to expand...

Surely for this thread, we exclude the availability of shoreside electrical power?

jono_howlett said:
The problem with forced air is that any leak between the exhaust and the fresh air could be disastrous.
Click to expand...

Need there be even a remote likelihood of such a leak, or of contamination generally? I mean, if the burner's exhaust is ducted by fan to, say, the pulpit, while the input for the heated air comes from the cockpit (or is recirculated from the already warmer interior)...

...why should exhaust gases ever get below? Particularly if the whole burner-unit is mobile and can be located on deck.

I'm dismayed by AntarcticPilot's (probably very accurate) analysis of what's safe, what's practical, what's possible and what it costs...and by the "Oh well, reach for the tea-lights" attitude. No disrespect intended, AntPil, but I'm gonna do it better, and heaps more cheaply! :)
 
dancrane said:
I'm dismayed by AntarcticPilot's (probably very accurate) analysis of what's safe, what's practical, what's possible and what it costs...and by the "Oh well, reach for the tea-lights" attitude. No disrespect intended, AntPil, but I'm gonna do it better, and heaps more cheaply! :)
Click to expand...

Well, if you manage it, it will be a boon to yachtspeople everwhere! Good luck!
 
Those of you advocating unventilated heaters in a boat should take note of THIS. Any appliance burning hydro carbons (including parafin/candles/tea lights) in a confined space should be used with the utmost caution.
Externally flued appliances are the only safe solution to heating away from shore power. As somebody has already pointed out, Propex gas heaters are much cheaper than diesel and, allegedly, have a lower electrical current requirement.
 
Something like:
http://www.ebay.co.uk/itm/ROVER-75-...756&pid=100011&prg=1005&rk=2&sd=170929978931&


seems a good answer.
If you used it to heat up a radiator of some sort that held a fair amount of water, it would continue to give out heat for a long time.
In my view, the main advantage of a heater in a boat or vehicle is reducing damp. An unflued combustion heater is mostly counterproductive and/or dangerous.

Some other possibilities might be to have a combustion heater of some sort outside of the living space nad bring the heat in using 'heat pipes', or a small flued heater based on something like the volcano kettle?
 
lw395 said:
Some other possibilities might be to have a combustion heater of some sort outside of the living space and bring the heat in using 'heat pipes', or a small flued heater based on something like the volcano kettle?
Click to expand...

Buddy, are you taking the Mickey?! That's what I've been saying, steadily and continuously, against a chorus of tea-lights! :D
 
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