Quote Originally Posted by shellkamp View Post
Just be aware that when you simulate the 95 degree ambient, that it won't be the same as the real deal due to altering of the heat transfer characteristics of the coil. You could have a 115 degree Saturated condensing temperature but due to the lower airflow the subcooling (and therefore BTU output) will not be the same as it would be when it is actually 95 degrees out. A TXV system would fare better than a fixed orifice system using this method.

It really should only be used to get you in the ballpark as far as charging the system in cold weather.
Curious,

I always thought that if my liquid line was 95 and a clean condenser puts out a liquid line temp that is within 2 or 3 degrees of ambient, then it is exactly the same thing as running the condenser in a 92 to 95 degree ambient. Am I missing something?

I understand that most condensers are designed with a dedicated sub cooling circuit that - of course - will not really get used as such when the condenser is wrapped with a tarp. But if one moves 2 tons of BTUs with a big coil and 95 degree air as one does with a little coil (made so by a trash bag) and 30 degree air, then the refrigerant doesn't know the difference. My subcoolong readings bear that out very consistently. And this is the design philosophy behind flooded condenser systems. Can you clarify your viewpoint maybe? Just because I am sure does not mean I am right.

You cannot really tell if the coil is dirty with this method of course, but for charging it is right on the money in my experience.

I liked to use super light weight plastic. Folds up small, and the air movement keeps it sucked up against the coil and in place. And it takes no time to set up whatsoever. Sometimes I borrow a trashcan lid and put my toolbag on it if I am too lazy to go to my truck to get it.

Dont forget to run the furnace for a few minutes to give yourself a little load in the space if it is cool inside.