Hi, has anybody worked with heat pumps? I'm recently confused about how the heat pump compressor operates. Does it have a fixed pressure or it actually adjust its pressure automatically to outdoor temperature variation? All my confusion originate from the following problem: Now we have a heat pump that employs vapor compression refrigeration cycle for cooling. Suppose indoor temperature is 55 F(12.7 C) and outdoor temperature is 95 F(35 C), try to determine the parameters that compressor should be operating so that COP of 6 can be achieved. Then use the determined parameters to calculate COP when outdoor temperature is raised to 105 F and indoor temperature stays the same. For the sake of simplicity, assume saturated fluid in the condenser and saturated vapor in the entrance of compressor. Any suggestion will be much appreciated. Thanks.