[Market-farming] heat cables

Etienne Goyer etienne at lejardinduvillage.ca
Tue Feb 17 15:23:56 EST 2015

I use them in two ways:

 - Dug about 8" underground to warm the soil for early transplants;

 - About a foot apart above ground, to warm the air under the row cover
of very early transplants.

In 2013, I also built a 4' x 8' seedling table with an 80" cable, loops
5-6" apart buried a couple inches in damp sand.  It worked very well,
but the table is just too heavy to be practical.  This year, I want to
build something similar, but lighter-weight (styrofoam under the cable,
and some conductive material on top to spread the heat).  I've read
somewhere that you need about 12W per square foot to provide adequate
heat; Easy Heat cable usually deliver 5W per linear foot (80' cable =
400W), so you can do the math for yourself.

Good luck with that!


On 15-02-17 09:08 AM, Beth Spaugh wrote:
> Thanks Etienne. That is exactly the one I have.  I am using an extension
> cord (not much choice), but a real heavy duty one (DH is a carpenter so
> we have heavy ones).  I did not leave it on long last night when
> testing.  I will turn it on today and leave it to test. I may have to
> forgo the thermostat automation and just turn it on in the afternoon to
> heat the plug trays and leave it on over night.  I was originally
> concerned about "cooking" the plugs, but don't think that will be a
> problem.
> Reassuring to know they work for you. I have them strung 6 to 7 inches
> apart. How close are yours?
> On 2/17/2015 7:02 AM, Etienne Goyer wrote:
>> I am using this brand of heat cable:
>> http://www.homehardware.ca/en/rec/index.htm/Heating-Ventilation-Cooling-Home-Comfort/Heating/Cables/Roof-Pipe/61-Meter-Roof-Gutter-De-icing-Kit/_/N-2pqfZ67l/Ne-67n/Ntk-All_EN/R-I5513269?Ntt=heating+cable
>> It does get quite warm, although not to the point that you cannot hold
>> it in your hand when plugged in.
>> You probably thought about it already, but just in case, have you tried
>> to plug it somewhere else?  If you use an extension cord, for example,
>> perhaps you don't get enough amps to get the cable real warm.  Something
>> to try.
>> On 15-02-16 09:04 PM, Beth Spaugh wrote:
>>> There was discussion that some folks used roof gutter deicing cables for
>>> bottom heat.  How warm do these get?
>>>   I just set up an 8 x 16 foam "table" with 200 feet of the cable.
>>> Before
>>> putting plants on figured I'd better test. The cable barely gets warm,
>>> certainly not hot.  I was planning on using this in my unheated
>>> hoophouse to keep seedlings from freezing at night.  I can't see that it
>>> will put out near enough heat, fast enough.  I have it on a "cube"
>>> thermostat, to come on at 35 and off at 45.  I was planning on keeping
>>> the whole thing full of flats, and that the heat would come up through
>>> the plugs, making nice warm roots. Seriously doubting this will happen.
>>> Hopefully after this week we will be done with frequent below zero
>>> nights.  I know that with frequent daytime sunshine, under row cover it
>>> seldom gets below 15.  Because of condensed ice on the bottom of the row
>>> cover.  If it doesn't freeze I don't know that I'll get that extra
>>> protection.  But I do have three layers of ag-19 row cover plus a light
>>> plastic, and can lay foamboard over the top (sides just row cover and
>>> plastic).
>>> Those who have used these -  please chime in with your experience. Thank
>>> you.

Etienne Goyer  -  Le Jardin du Village

"Changer le monde, une betterave à la fois"

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