Muggles wrote:
On 10/11/2015 11:44 AM, Bob F wrote:
Muggles wrote:
On 10/10/2015 2:02 PM, Bob F wrote:
Muggles wrote:
On 10/10/2015 11:48 AM, Don Y wrote:
On 10/10/2015 5:40 AM, Stormin Mormon wrote:
On 10/9/2015 4:44 PM, Muggles wrote:
Roof de-icing cables? hmmm I've never worked with those or
heard of them before. How efficient are they? I'm looking for
any idea that might work.

Eventually, we're installing some solar panels to run anything
we might need in the green house, but right now it's all on
the grid to the more efficient the heat source the better.

Pretty much all electric heaters are the same
efficiency. 5,200 BTU per hour with 1500 watt
consumption.

From what I can see here, the big problem is
heat loss over night. Consider focuss your
efforts there. Vapor barrier to slow evaporation?

It takes 1 BTU to heat a pound of water 1 degree. Let that
pound of water *evaporate* and you've LOST ~1000BTU's!


As it evaporates, does it not warm the surrounding air?

Sure! That's how evaporative coolers work. ;-)



mmmmm If the air is 50° and the water is 70° and some warmer water
evaporates, the evaporation would be cooler than the 70°, but still
warmer than the 50°, right?

The air will be cooler and more humid than previosly. In dry
climates, evaporative coolers really do cool. The water cools as it
evaporates, and the resulting cooler vapor cools the air.

https://www.google.com/search?q=how+...utf-8&oe=utf-8

So, the evaporating air might cool down to from 70 to 60 as it
evaporates, but then warm the air from 50 to 60?

NO

The water evaporates, thereby cooling the air.

Notice the smilie at the end of
"Sure! That's how evaporative coolers work. ;-)"

That means I was kidding.