12v heater

I used the "upside down plant pot heater" last year.

It seemed to work quite well, but I could never get the warmth down to floor level: some old story about heat rising.

I would strongly recommend thick socks as an adjunct to the plant pot

Plant pot......cheap, easy to install, very reliable, works
Ebers..........costly, difficult to install, very unreliable, works sometimes

An easy choice really, especially for a small boat
 
i recently bought a catalytic gas heater that uses catridges (similar to camping type) costs appro £90 and it is very safe, it has oxygen deplition shut valve and anti tilt shut valve; 1.5 Kw; it is used by lorry drivers. It is very small and basically it is brilliant. Be careful, there are a lot of heaters on the market using catridges, however, to my knowldge, only one make is suitable for indoor use.
 
google "coleman blue cat"works really well although I
wouldn't sleep with it on
cheers Joe
 
[ QUOTE ]
Ebers..........costly, difficult to install, very unreliable, works sometimes

[/ QUOTE ]

Is this your opinion or a point of fact?
 
Restless has a Rutland 503 wind generator and a 36W solar panel. These should give up to 80W, but 20-40 is more realistic. The plan this winter is to install a 60W tube heater, to keep the chill off and the boat dry.

I have a "fridgemate" to switch the heater off when the batteries are low, and also a thermostat.

The only tube heaters I could find are 240V, so will be connected (to a 270Ah domestic bank) by a 300W invertor (also controlled by the fidgemate).

Any views from the panel before I install this ?

John
 
IMHO, 60W is a negligible output to heat a Konsort, think of a smallish light-bulb. The inverter will also require some power over and above it's output to the load, but this will also appear as heat in the boat. I would expect the set-up to give virtually no benefit in terms of temperature and dryness, and you will have flat batteries into the bargain.
Regarding the inverted plant-pot, this defies the laws of physics. Apart from possibly altering the temperature profile of the cabin very, very locally, there will be no overall effect in terms of general warmth.
 
I believe that the type of battery regulator used with both wind gens and solar panels are "shunt" regulators - when the battery is charged to maximum voltage, the regulator starts to dump the excess current to prevent overcharging the battery.

Another way of putting this, is that the regulator itself will already produce heat from any energy in excess of that required to keep the battery topped-off.

Will that be sufficient to keep the boat toasty? (I doubt it somehow...)

Alan
 
The excess is dumped to a resistor, but this does not heat the controller up very much. The tube heater, on the other hand, gets much warmer - certainly too hot to hold. I think the tube heater will be more efficient, but I too have doubts as to whether the heat output is suficient.

The batteries should not go flat if the fridgemate does its job.

I may do a temporary installation to see how it works, and report back.

John
 
Energy is energy - if it is simply being dumped, then there isn't a "more efficient" or "less efficient" way to do it. The heat produced will we proportional to the energy being dumped. Period.

The only efficiency issue is how readily the heat produced is emitted (convection, conduction or radiation etc), and Newton's law of cooling comes into effect in respect of temperature rise of the emitter.

So basically, no matter how efficient the emitter is, once it has reached steady-state, the heat output will be identical (it has to be).

But I think we agree that it won't be very much... (it will at least, NOT be running down the battery, as it is only using the *excess* energy).
 
I liveaboard with a Taylor's paraffin heater which does the job, although you have to prick the jet every few hours so isn't too practical for overnighting. Ideally I would have gone for a solid fuel burner at low level but that would have meant significant messing around with internal layout...

I'm based in a marina so have the luxury of mains, and run a dehumidifer in the winter to keep condensation down, and this also is effectively a 250 W heater.

just a thought on ventilation - if you open lots of hatches/windows to keep the moisture/CO out you are throwing away most of the heat you are generating...

I suggest good quality sleeping bag/bedding, slippers, practise getting gdressed very quickly, and a breakfast diet of porridge or something else hot!

or move to the Carribean.
 
As far as I'm aware, the mode of operation of the Fridge Mate isn't suitable for your proposed application. Left to its own devices, the Fridge Mate only turns on when it detects a battery voltage at charging level, and turns off when the voltage drops below charging level (there's no data on the Fridge Mate website so I can't be specific about voltages).

Your proposed 60W heater and inverter will probably draw 6A or so, and unless your wind and solar inputs are charging enthusiastically, as soon as the heater switches on the battery voltage will dip below charging and the Fridge Mate will turn the heater off. On a sunny, windy day, you'll maybe get the heater on for a while, but surely this is the time you don't need it. You need it to come on when the temperature drops, and I think you'll find it won't.
 
Whilst I agree that the total energy dissipated will be the same, the useful output depends on the surface temperaure and emissivity of the heater. I don't want to argue the physics (see Stefan-Boltzmann Law if you want further details), but I suspect that most of the heat dumped by the regulator produces a local, but low temperature increase in the local boat fabric (and the wiring) which has very little effect other than warm a small part of the hull, whereas the tube heater may be better at putting the heat where it is needed.

I will experiment, and report back.

John
 
[ QUOTE ]
As far as I'm aware, the mode of operation of the Fridge Mate isn't suitable for your proposed application. Left to its own devices, the Fridge Mate only turns on when it detects a battery voltage at charging level, and turns off when the voltage drops below charging level (there's no data on the Fridge Mate website so I can't be specific about voltages).

Your proposed 60W heater and inverter will probably draw 6A or so, and unless your wind and solar inputs are charging enthusiastically, as soon as the heater switches on the battery voltage will dip below charging and the Fridge Mate will turn the heater off. On a sunny, windy day, you'll maybe get the heater on for a while, but surely this is the time you don't need it. You need it to come on when the temperature drops, and I think you'll find it won't.

[/ QUOTE ]

Thank you for your input, pvb.

The fridgemate is actually rated at 8A, but I will only use it to drive a relay, so that the invertor and heater can be switched together.

It is also claimed to be compatible with wind/solar generators - I think there is sufficient hysteresis in the system to allow for this. Again, only experiment will show this.
 
It might be worth bearing in mind that the rate of heat loss from something like a small boat will be enormous - especially if you have to keep it ventilated to avoid gas / condensation build-up.

Even a modestly sized car heater is likely to be capable of dissipating several kilowatts (say 5 or so) and I imagine the losses from a saloon car would be less than even a pretty small boat. Certainly 1.6kW in our 27 footer doesn't go very far!
 
[ QUOTE ]
The fridgemate is actually rated at 8A, but I will only use it to drive a relay, so that the invertor and heater can be switched together.

[/ QUOTE ]The rating of the Fridge Mate isn't really relevant - it's the voltage of the battery which will be the deciding factor.
 
[ QUOTE ]
Even a modestly sized car heater is likely to be capable of dissipating several kilowatts (say 5 or so) and I imagine the losses from a saloon car would be less than even a pretty small boat. Certainly 1.6kW in our 27 footer doesn't go very far!

[/ QUOTE ]

Has anyone actually used heaters such as these, and if so, how many are needed to make a difference?
 
I seem to have hi-jacked this thread (sorry atelford). I also realise that 60W will not keep the boat warm and dry, but it is all I have got, and I would rather like to put to some use.

If I don't go down the tube heater path, how about a dehumidifier ? I think these would take about 240W (including the invertor losses, so I am looking at 20A. My 270Ah bank should be good for at least 4 hours use before I shut off the unit and let the batteries re-charge. 2-3 days later when the batteries have recharged I could repeat the process.

So, would this be enough to keep Restless dry ? I can switch units on/off and monitor the battery voltage remotely, so I could set this up fairly easily.
 
[ QUOTE ]
Ebers..........costly, difficult to install, very unreliable, works sometimes



[/ QUOTE ] On what basis do you make this sweeping statement?

I suspect that the reason Eber's have a bad reputation is that many of them are second hand heaters from commerical vehicles that are poorly installed on the cheap.

We bought a new Eber three years ago and its never failed yet. (That's condemned the thing to early failure!) It was installed EXACTLY according to the makers spec and it puts out an amazing amount of heat very cheaply and efficiently. I agree that the a new Eber kit isn't cheap, but you get what you pay for. I am not even arguing for Eber per se - I suspect Webasto are equally as good, but we don't have one of those.

It also wasn't difficult to install!
 
Absolutely right - properly installed, Eberspachers are superbly reliable. Mine's 18 years old and works very well.

Virtually all the "problem" posts about Eberspachers relate to people who buy used units on eBay and then try to install them with no knowledge.
 
You must log in or register to reply here.

Other threads that may be of interest

W
Battery suicide
Replies
17
Views
579
Refueler
Refueler
UK-WOOZY
Autoterm 4kw heater was blowing smoke out into the cabins
2
Replies
21
Views
578
mjcp
M

Share this page

Top