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Temperature of Heating Cable?
David_Caple
Posts: 3
Hi, first post and although an 'interested gardener' (I like to experiment with such as growing from the fruit and veg you buy!) I am asking for help on a not direct gardening issue but the operation of heating cable ...
Has anyone ever measured the actual operating temperature of the heating cable they use?
I don’t mean the temperature of the soil because that will depend on such as the concentration of the cable layout, the ambient temperature of the location, the volume of sand/soil the cable is heating etc. ... I mean the temperature of the cable itself. I’m thinking it may provide me with a warming solution I am looking for for a project. 😊 All contributions gratefully received. Thanks for reading.
Never doubt the courage of the French ... they discovered snails are edible! 
0
Posts
The temperature that the cable will reach is dependant on many factors.
Ambient temperature, resistance of the cable, how quickly the heat is transferred from the cable to whatever it's heating, and I'm sure there are other factors involved too.
If the cable is dangling in the air it will reach a different temperature to what it would reach if it were immersed in water
If you can give us some idea of your project, maybe we can come up with some suggestions.
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
So if the loss of heat from the surroundings is restricted and the heat output from the cable is higher than the heat loss to/of the surroundings then it and the surroundings will reach the maximum temperature of the cable.
All I'm wanting to do is to slowly/gently heat a cylinder by wrapping the cable around the outside and insulating so that (nearly) all the heat is going into the object and not lost to the outside (the opposite to a heated propagator where the heat source is inside the object which then loses heat from it's outside surfaces).
So going back to the first paragraph if the heat generated by the cable going into the cylinder from the cable is greater than the heat lost through the insulation to the outside then theoretically the cylinder will eventually reach the same temperature as the cable. I just need the temperature of the cable so I can then calculate the the length of cable (watts) I will require and a suitable thermostat.
I have an interest in thermodynamics (relating to quantum field theory...) but that's not helping me with your project.
If you use a 1m heated cable that will probably use something like 25 watts.
If you use a 5m heated cable that will use something like 125watts
So the longer cable will heat whatever it is much quicker, but won't alter the final temperature.
Either cable will heat to the same temperature, but the longer cable will do it much faster.
What's wrong with doing it the old fashioned way?
Buy a heating cable and thermostat and set the thermostat to the temperature you want to achieve.
Or am I missing something?
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
I've tried asking suppliers but they are scared s**tless of their product being used for a non standard procedure and claim they don't know so I thought ask people who are using it. I have an old cable from 40 years ago I no longer use but cannot find it. If I could I would experiment with it. I'm wanting a cable that produces as least 40C and preferably 50C or maybe more. For the reasons I have already given that's not to expect a propagator to run at those temperatures!
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.