Bulbs as Heaters

[Ian_Rob]

There is a thread on an American forum that questions the safety of using light bulbs as a heat source in a bilge (and presumably therefore an engine bay) though much of the argument relates to sparks and contributors guesses on what their insurers interpretation would be.

Assuming the gas is off, I can perhaps see a risk where there is petrol about but diesel.....???

 

[Ian_Edwards]

I've successful used a 100 watt old style tungsten filament bulb as a heater in the cabin of a small yacht. I suspended it on its flex about 1m below a hatch, which was left open on the ventilation catch. I.e. a couple of centimetres.
The air circulation caused by the hot bulb was suffice to keep the boat well ventilated.
I left the bulb on all winter with any problems.

 

[Momac]

I think some people see risks in everything.

Rather than a bulb I use a tube heater in the engine bay and a radiant heater near the calorifier. Both controlled by thermostats .
I dont have any oil of fuel leaks but the engine bay heater is located clear of any possible drips from the engine.

 

[sarabande]

here are some figures for the surface temp of incandescent bulbs

25W - 110F
40W - 252F
60W - 260F

Those are for ambient air temp of 77F.

In a closed space (e.g. engine compartment) in theory all the bulb W is converted to heat/light energy, either radiant IR/visible spectrum, or through convection. But shining a light or relying on minor warm air movements (and the tendency of warm air to rise upwards) seems a very ineffective way of indirectly keeping the engine block warm.

To me, the sensible (joke ) way to keep the engine warmish is to wrap a heating strip round the block or some handy pipework and then heat the block directly. OK, in the end, the warm air from the engine will rise up to the top of the box...

http://www.coleparmer.co.uk/Category/Heating_Tapes_Cords_Blankets/2059

https://heatingtapes.com/collections/silicone-industrial-tape

I wonder whether putting light bulb into an engine box is more about the perceived comfort factor of the human being.

 

[PaulRainbow]

But why ?

My car engine lives outside and gets sprayed with dirty water everytime it rains and dirty/salty water all winter. Why does my boat engine need to be nannied ?

 

[dom]

But why ?

My car engine lives outside and gets sprayed with dirty water everytime it rains and dirty/salty water all winter. Why does my boat engine need to be nannied ?

Does your car have a seawater side?

 

[ghostlymoron]

I've asked similar questions before and was told it's irregular use and salty environment. But still seems odd to me. My current car has done 95k with minimal attention and previous ones did 150k before I swapped them. The engines were still starting and running well and not consuming oil or excessive fuel. By minimal attention i mean serviced at recommended intervals which is just oil and filter changes for a diesel.
Boat engines don't survive as well.

But why ?

My car engine lives outside and gets sprayed with dirty water everytime it rains and dirty/salty water all winter. Why does my boat engine need to be nannied ?

 

[doug748]

I have used a bulb in an inspection light housing for the last 4 winters or so, placing it underneath the sump. Its on a timer so the power use is small but it keeps condensation off the engine in cold snaps and nothing is lost as the waste heat helps to keep air moving through the boat.

When I asked, on here, I was assured that a tube heater would be no more efficient, the bulb is smaller and handier and I use the inspection light anyway.

Many will recall the days of car sump heaters - paraffin devices placed under the engine of our Dad's old petrol cars.

 

[ghostlymoron]

When I was on construction sites in the 70s, we used to light a small fire under our Winget dumper to warm the engine before attempting to hand start it.

 

[lw395]

I do know someone who nearly set fire to his boat with a bulb. Somehow the lamp got moved and ended up on the chart table which got properly scorched. I suspect it was a halogen lamp.

 

[ex-Gladys]

I thought incandescent bulbs can't be bought any longer? A CF or LED won't give off much heat

 

[David2452]

My major objection is that a bullb will probably blow far more frequently than a tube heater will fail and therefore less reliable as a protective device.

 

[martinriches]

A lot of cars are kept in a salty environment as well. The marina car park where I keep my boat is usually full. The village nearby is full of cars and vans. The engine on my boat is enclosed in compartment, yes it does have some ventilation but no where near that of a car engine in a similar environment.

Martin

 

[ghostlymoron]

You can still buy them on internet and get heavy duty ones from some shops.

I thought incandescent bulbs can't be bought any longer? A CF or LED won't give off much heat

 

[Scubadoo]

You can still buy them on internet and get heavy duty ones from some shops.

Halfords sell inspection bulbs and as said heavy duty and less likely to fail, however I would only use tube heaters.

 

[Ian_Rob]

Re: Bulbs as Heater

I bought a 150w ceramic bulb; the type used to keep reptiles warm but having checked it with an infra red thermometer the bulb has a surface temp of at least 400 degrees C, far hotter than the Sarabande's figures for an ordinary bulb. It may well be hotter still but that is as high as my IRT will measure. Thought it was a good solution but not so sure now.

 

[No Regrets]

Re: Bulbs as Heater

The thought of replacing a cheap reliable tube heater with a bulb fascinates me, and not in a good way!

The tube heater should last for years, if not decades, exists only to provide heat, and is tough, resistant to knocks, therefore the correct tool for the job.

A bulb is a bit futile by comparison.

Why on earth would anybody want to replace the inferior item with the obvious choice!?

Comparing a car engine, which is totally protected with it's sole coolant source with a boat engine which usually has both the internal (coolant) cooling and the external (raw water) coolant is really thick.

 

[PaulRainbow]

Re: Bulbs as Heater

Comparing a car engine, which is totally protected with it's sole coolant source with a boat engine which usually has both the internal (coolant) cooling and the external (raw water) coolant is really thick.

Probably not as thick as thinking a tube heater in the engine compartment will somehow protect my engine from whatever the left over seawater is doing to my already 35 year old engine. Doh!

 

[Ian_Rob]

Re: Bulbs as Heater

The thought of replacing a cheap reliable tube heater with a bulb fascinates me, and not in a good way!

The tube heater should last for years, if not decades, exists only to provide heat, and is tough, resistant to knocks, therefore the correct tool for the job.

A bulb is a bit futile by comparison.

Why on earth would anybody want to replace the inferior item with the obvious choice!?

From an earlier thread, 60w is a little on the light side for the volume of my engine bay where conditions drop below -2degrees C. A 120w tube heater, which should be installed horizontally, is too long to fit. 2 x 60w tube heaters (£40.00), 120w Ceramic Bulb (£6.99).

 

[maby]

Does your car have a seawater side?

It's not only the engine cooling circuit. Living in the south of England, I'm fairly relaxed about the engine - the freshwater cooling circuit is protected with antifreeze and its exceedingly unlikely that the raw water side will ever freeze. My concern is more the drinking water supply to the boat - that could freeze and burst pipes.