Most of my original cooling/ heating plan came from Atlas. I told them I needed to maintain ~85-86 in the greenhouse year round. They recommended a 100,000 BTU furnace so I bought a 150,000. They recommended two HAF fans and the exhaust fan, so I bought four HAF fans. As an added measure of insurance, I planned the DIY evap pads myself. As an extra measure of increasing the evap capacity of the pads, I started thinking about the salt or other desiccants. Not trying to make any points here, just want to lay out some foundation for the archives and other people as a getting started point.
Man, some of this stuff seems a little backwards to me. I thought an evap pad is supposed to cool the air coming into the GH. If the water in the trough cools down because it gives up it's heat to the air, how does that lower temps inside the greenhouse? Or am I just missing the boat entirely?
I really don't get the concept of removing water from air making the air warm up either. I was almost there because I started thinking that if adding moisture to air makes air cool down (like with an evap pad), then the opposite (removing moisture from air makes air heat up) must be true too. But H2OENG, you say the air actually warms as moisture evaporates into it? And cseeton says the air warms up when moisture is removed? Surely I must be missing something somewhere or you guys are talking about two different ideas???
The psychrometric chart must provide allot of info to someone with the knowledge to interpret it. To me it just looks like a plate of spaghetti. OK, now I'm hungry.
tschopp- now there are some concrete numbers I can understand.
Evaporate X amount of water per day to achieve a certain temp.
Actually, I was counting on getting a contribution from both evap off of the tanks (especially with the four HAF fans and/or big exhaust fan running) plus from evap cooling of the air coming into the greenhouse. I thought the salt would work better than everyone else thinks it will and allow more potential evaporation from the tanks. Oh well, better to get all of this stuff figured out now than try to do an "emergency" cooling brigade this summer.
matt- Actually, there is a natural pond about 1/2 mile away from my house. Could you imagine the size of the pumps required to get water there and back?
scubadude- dripping kalk was/is my plan. It's what I use on my private aquarium so I'm familiar with it. I also use hydrated lime. Cheap, supplements calcium and alkalinity, and keeps pH up. I have been reading and thinking about the slurry method of adding kalk as well. Then just using buffered water for top offs.
OK, so how about using rice as a desiccant? Sorry, I just couldn't help it. ;D
What about using the kitchen scrubber pads (cut smaller- say 2' x 2' or 18" x 18") standing up vertically above the tank and perpendicular to the airflow created by the HAF fans, have the tank water pumped up to trickle down the pads? Or a little muffin fan for each pad/ tank.
hammerhead- from one layman to another, It sounds like it would work as well as anything being discussed. The extra expense would be a consideration for this project. If i can basically do the same thing with the swimming pool, that saves me money.
The swimming pool also has a deck so there would be some shade to place a big exchanger.
Lego- to my brain, that sounds like an extraordinary idea. Little (or big) submersible chiller units. Wonder how much electricity they would gobble up compared to a pump or two?
