Soil warming cable, constructed a bed

[Ruud]

i know how to make a bed up but it states with the cable to keep the sand moist. i have 10cm of sand how will i keep it all moist?

i know i could moisten the sand as i add it, but its keeping it moist top till bottom

thanks

[Aberdeenplotter]

i know how to make a bed up but it states with the cable to keep the sand moist. i have 10cm of sand how will i keep it all moist?

i know i could moisten the sand as i add it, but its keeping it moist top till bottom

thanks

mix the sand with water until it is sufficiently moist before you add it to your growbox. I have a sheet of thick polythene under the sand, another sheet above and then a layer of that fabric stuff that holds water which my tired brain can't remember the name of on top. I also fitted a thermostat and also use a soil thermometer to check that stat is working properly.

Edit note. Thanks to the girls in the rant thread for reminding me it is capillary matting.

[Ruud]

Soil warming bed help

Hi

i have made a heat bed roughly 4ft long
5cm of sand then warming cable, then another 5cm

thermostat set to 30c its been 24 hours and the sand is still cold, you can only briefly feel the heat when you place your hand above the sand.
the bottom is lined with pondliner

is something wrong?

[Kristen]

The sand need to be damp I think? (My thinking is that Dry sand will be a good insulator)

[Ruud]

so i need to water it then?

[Kristen]

If its bone dry then I would think you do, yes.

(This may be helpful:

http://www.growfruitandveg.co.uk/gra...bed_54495.html

[SarzWix]

I have merged the 2 threads as they appear to be talking about the same thing...

[Ruud]

ive Watered it till moist and its still pretty cold to the touch

[Kristen]

Are you sure it is working? Only way I can think to test is to turn everything off in the house and see if the meter is still going round (or going round "more") when soil warming cable is on. Its probably very low wattage though, so probably not going to make the meter run very fast at all, so difficult to detect whether its working, or whether the fridge just cut in instead!

Lets hope that's not the problem though.

[Ruud]

the thermostat has a red light , which is on
just been out and the sand is still cold

[Kristen]

the thermostat has a red light , which is on

Ah, that sounds like a much better test

Sorry, out of ideas now, but I hope you manage to get it solved.

[SarzWix]

Try removing some of the sand?

[Ruud]

Try removing some of the sand?

but it says it needs to be 10cm

[Glutton4...]

Can't you just dig down to the cable and see if it's working? Or am I missing something?

[SarzWix]

I *think* the problem is that the cable is getting hot but the heat isn't being conducted through the medium. So maybe a bit less medium would work. I dunno, I'm no expert, just suggesting what I'd do if it was mine.