Tube heaters

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doug748

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I was going to fix up a 30Watt bulb in the boat, under the engine, to keep the air moving and stave off frost.

However I see that small tube heaters are available that consume a similar amount of power; they cost about 15 quid.

My question is how much more efficient are these heaters at heating? I know someone will know, thanks.
 
doug748 said:
I was going to fix up a 30Watt bulb in the boat, under the engine, to keep the air moving and stave off frost.

However I see that small tube heaters are available that consume a similar amount of power; they cost about 15 quid.

My question is how much more efficient are these heaters at heating? I know someone will know, thanks.
Click to expand...
30 watts is 30 watts
tubes are much safer that an incandescent bulb
check out cpc farnell site
 
For the last 4 winters, when not in sailing mode, our boat has an 80W tube heater permanently on under the engine and a 160W tube heater in the salon.
This is on the same circuit as our dehumidifier, both controlled through a timer and both are on 11am to 4 pm.

Works well-the electricity cost under 70 quid at Port Solent last winter, including our nights aboard and use of fan and oil radiators.
 
rotrax said:
For the last 4 winters, when not in sailing mode, our boat has an 80W tube heater permanently on under the engine and a 160W tube heater in the salon.
This is on the same circuit as our dehumidifier, both controlled through a timer and both are on 11am to 4 pm.

Works well-the electricity cost under 70 quid at Port Solent last winter, including our nights aboard and use of fan and oil radiators.
Click to expand...
I use a plug in 13 amp thermostat to control an oil filled rad. why have heating on when it isnt needed

http://www.tlc-direct.co.uk/Products/SMET05.html
 
I'm guessing that the boat is out of the water?

Am I right in thinking that if the boat's in the water, you don't have any worries about freezing?

If the engine's covered/enclosed I thought you don't have any fear of frost either, as it falls from the sky?
 
sailorman said:
30 watts is 30 watts
Click to expand...

Certainly true, but not necessarily relevant. The rated wattage of an electrical device is a measure of the electric energy it uses. As energy is for most practical purposes conserved, the device converts that energy into a different form or forms, for example heat, light, sound or kinetic energy. The OP is interested in heat, and you would not get the same amount of heat produced by the same wattage of, say, a resistive heater, an incandescent light bulb, a fluorescent tube, an LED array and an electric motor.

The OP wonders if the heat output of a dedicated heater is sufficiently greater than that of an incandescent light bulb of the same electrical wattage to justify the additional expenditure. None of the replies so far has addressed this question.
 
alan_d said:
Certainly true, but not necessarily relevant. The rated wattage of an electrical device is a measure of the electric energy it uses. As energy is for most practical purposes conserved, the device converts that energy into a different form or forms, for example heat, light, sound or kinetic energy. The OP is interested in heat, and you would not get the same amount of heat produced by the same wattage of, say, a resistive heater, an incandescent light bulb, a fluorescent tube, an LED array and an electric motor.

The OP wonders if the heat output of a dedicated heater is sufficiently greater than that of an incandescent light bulb of the same electrical wattage to justify the additional expenditure. None of the replies so far has addressed this question.
Click to expand...

The OP refers to a 30 watt bulb, ie a bulb which consumes 30 watts of electrical power.
The power emitted as light is in the region of 0.6 watt. That light will in any case be absorbed by surfaces around it and converted into heat. So the heat you get from a light bulb will be the same as you get from a heater of the same electrical power.

The answer to the question, "is the heat output from a dedicated heater sufficiently greater than that of an incandescent light bulb of the same electrical wattage to justify the additional expenditure" has to be, "No it is not , the heat outputs are effectively the same".

IMO though a tubular heater is a far more sensible heat source and is less likely to burn out than a light bulb.

Hell why am I doing Physics, of all subjects, at 2o'clock in the morning ? ...... good night!
 
A 30 watt heater will do very little in a boat, maybe slightly reduce condensation but not much more. I put an 80 watt tube heater in my very well insulated motorhome, where it had no detectable effect when the outside temperature was below freezing. When we kept our boat in Holland we had two 250 watt heaters below, set low on their thermostats.
 
Never had much luck with tube heaters, the amount of heat they put out is pretty puny.
As above, I now have a 600w oil rad connected to a froststat in the engine bay.

FWIW the temp in the engine bay, boat in the water has never gone below 5°C over the last 5 years, measured by my max min thermometer.
 
Vara said:
Never had much luck with tube heaters, the amount of heat they put out is pretty puny.
As above, I now have a 600w oil rad connected to a froststat in the engine bay.
Click to expand...

I would've struggled to get a tube heater in our engine bay let alone an oil filled radiator ...

I no longer have those problems - but think about it - the car sits on the drive, do you put a heater under the engine?
 
Well thanks for all the contributions and particularly to alan_d for putting things on an even keel.

So the answer is we don't know but suspect the difference is small, which is quite remarkable really. It hinges on how much of VicS's 0.6 of a watt of light is reconverted to heat.

Anyway it is very simple just to leave my inspection light on, rather than paying for, setting up, lugging and re-lugging a heater that isn't that hot.
 
Well thanks for all the contributions and particularly to alan_d for putting things on an even keel.

So the answer is we don't know but suspect the difference is small, which is quite remarkable really. It hinges on how much of VicS's 0.6 of a watt of light is reconverted into heat.

Anyway it is very simple just to leave my inspection light on, rather than paying for, setting up, lugging and re-lugging a heater that isn't that hot.
 
doug748 said:
It hinges on how much of VicS's 0.6 of a watt of light is reconverted to heat.
Click to expand...

In the overall scheme of things I regard 0.6 watt as insignificant.

It will all be converted to heat anyway. It has to go somewhere as some form of energy. unless your engine compartment has big windows that allow the light to escape it can only end up as heat.
 
The difference between an oil filled heater and an incandescent bulb is the temperature at which it radiates heat.

Heat is radiated in proportion to the absolute temperature to the fourth power, so hot things radiate more heat, but the total energy emitted is the same (the sum of conduction convection and radiation). The only practical effect will be that surfaces near the incandescent bulb will get hotter. The higher surface temperature of the incandescent is arguably less safe, i.e. more risk of a fire.

I use a 2kw oil filled heater in the saloon, switched by a thermostat, which is set at 5 deg C. This keeps the cushions and fabric dry and free from mould.

In the distant past, I've used a 60watt incandescent bulb suspended below a skylight, which was just cracked open. This proved to be quite effective in circulating air around the boat. But I that case I wasn't concerned about frost.
 
I was advised not to use heaters in the cabin as they promote mould to grow due to the relative warmth, I was advised to just use a de-humidifier which has a drying effect and produces a small amount of warmth as a side effect.

However, as it is a petrol engine boat I do have a concern about electrical switching on and off in an enclosed boat. The engine and cabin are separate and there is never any petrol smell in the cabin, its an injected engine so there is no normal evaporation from a float chamber etc.

Is this ok?
 
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