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blackest


Latest posts by blackest

621 to 624 of 624

WEATHER this week

Posted: 13/03/2013 at 00:08

http://biomet.ucdavis.edu/frostprotection/Principles%20of%20Frost%20Protection/FP005.html

This kind of explains things, in a way which makes my head hurt. But I think the critical part is the conversion of latent heat into sensible heat. When water vapour condenses there is a release of energy which is the latent heat converting into sensible heat this warmth helps protect the plants slowing the temperature drop and delaying the formation of ice. If all goes well the morning sun will provide the heat back into the greenhouse before the frost can form. I think trying to delay the dew point by trying to avoid heat escaping ends up causing damage as the water vapour will directly form ice.

   

WEATHER this week

Posted: 12/03/2013 at 22:23

Artjak the can furnace is basically a box of black painted cans behind glass Cold Air enters at the bottom and exits as very hot air at the top. Which is ducted where it is needed (eg heating a  chicken coop) . Temperature went from 38 degrees F input to 130 degrees output. There are a number of idea's with a similar theme one i liked was done in 71 where a series of pipes was laid under slabs circulating water from an outdoor pool.  

Heres a strange idea told to me by my local nursery that itis better and warmer for the plants if you open the vents when a frost is due, he reckons closing the vents actually makes the plants colder.  yesterday he said it was 7 degrees warmer than the outside air! This I do not understand

 

WEATHER this week

Posted: 12/03/2013 at 10:22

nice sunny morning and warm behind glass quite perishing outside. ice in my greenhouse but the air temp is a comfortable 20 degrees so shouldn't last long.

I'm thinking about moving some breeze blocks into there, so the sunlight will warm the blocks and later the blocks will release the heat back into the greenhouse. I've been reading about people insulating with bubble wrap which might be an excellent idea to retain the heat from the sun. An interesting idea is the can furnace essentially warming air passing through the air and passing it to where it is needed. might try something like that too. 

The first Gardeners' World

Posted: 11/03/2013 at 11:04

was up at 8:15 sunday for the gardening programs and was a bit disappointing. Cottage gardening great , but autumn now!  Surely should be time to sow seeds. I'm already running into problems what with this cold snap.   Heated Propogators seem to be pretty much essential to raise the soil temperature. Still programs may improve as the season gets going. 

621 to 624 of 624

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1 to 15 of 27 threads