Heat exchangers transfer heat between a source fluid (liquid or gas) and a working fluid using heat pipes, fins, and heat plates. Shell and tube heat exchangers are simpler to install and easier to maintain than high-efficiency heat exchangers but take up more space and are less efficient at transferring heat. High-efficiency plate heat exchangers are smaller and more efficient than shell and tube designs but are harder to maintain and do not handle dirty or particulate-laden fluids well. Immersion heat exchangers are thin panel-style heat exchangers with a large surface area that are lowered into a tank or pool of fluid and transfer heat from one fluid to another. Heat exchanger replacement parts are used to maintain, install, or repair heat exchangers. They include replacement tube bundles, plates, and other parts that keep heat exchangers operational.