The first thing we have to do is measure for replacement door. You want to measure across bottom, center, and top of existing door frame to find narrowest dimension. Start outside and measure at point where old door frame stops and exterior material starts. That material can be stucco, siding, or brick. Measure across in 3 places: bottom, center, and top. Record smallest dimension. Then go inside and do same thing. You want to measure where frame ends and drywall, plaster, or sheetrock begins. Take all six measurements, find narrowest one, and deduct 3/4". That is width of new door. Now, when you measure height, you can do it just on outside. Measure left, center, and right side from ground where bottom track sits, up to top where old frame ends and exterior material begins. Take narrowest dimension and deduct 1/2". That is your height of new door. Then, determine which side sliding panel should be on. The fixed panel is designated by letter "O", and slider is an "X". In most areas of country, you call it out by looking at door from outside and reading left to right. So, if you were outside looking at your door, and you want sliding panel to close to right wall, you would ask for an "OX". However, because i have recently discovered that not all parts of country do it this way, my suggestion is to ask dealer how they read opening before placing your order.

Mechanical systems also have condensers. Condensers are found underneath steam turbines. Air-conditioning systems have condensers too.

How this name came about is a mystery to me. Perhaps it is because condenser is place for converting vapor or gas into liquid - at least for mechanical systems.

So it is a kind of heat exchanger. What is cooling medium?

For air-conditioning systems, most common cooling medium is water and air. The vapor to be cooled is refrigerant. And you've guessed it... It changes hot refrigerant gas into liquid.