Ask about Room AC

I am going to have the air out side sucking in at the bottom of the floor right next to the plants.
And the air in the room will be cleared in less than 5 minutes by a duck sucking the air out of the top of the roof.
I thank I am going to need something that will control the temp in that room to keep it at 78.
I am going to have a floor heater the will not let it drop to 70. but I cant thank of how to keep it cool and not let it get over 80. ?(keep in mind that the summers here get to a 110. and this is in the attic well insulated.) Any advice???
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One would assume that this is an old model? Because newer ones have digital control with precise temps to set.
It's duct by the way, not duck.

yeah if it does not have a temp gauge to set you can buy one pretty cheap, that way it will go on and off when you want

Old model what. I have not purchase any thing... I am going to buy a floor heater that has a digital gauge that I can set to 75 degrees. So it will not get to cold.
Now I need a AC that will not let it get to hot. I don't want to use a refrigerated air because it will take all the moister out of the air.And the plants need moister.
and I have no place for a swamp cooler. I will have a air intake duct and a air outtake duct.(Fans)

I was hoping that there was something I could buy that would keep the room at 78 degrees

here is a picture of the room. It is a 13' / 9' room.

There is a 24 ouch budweiser in the middle of the room next to my bong.

You are going to have a fuck of a time keeping the temp always within 3 degrees man. Seriously. And you are going to waste a hell of a lot of electricity. I would broaden that range myself.

The only way I can keep my humidity down to a decent range for flowering is with the help of my ac. Yea for vegging, it does suck the humidity out, but leave a couple bowls of water or a wet towel around to even it out.

so you recommend a refrigerator air unit? Like from walmart? Ps thanks for the humidity advise.I never would have guess to put bowls of water in the room.