My heater was boiling water in the heat exchanger and making a loud knocking sound whenever i turned it on for the last few months. After replacing a bunch of things, it was determined that the heat exchanger had reduced flow in it from some sort of blockage or buildup. Ordered this part, which arrived within 10 days. Installed it myself in about an hour. Instructions were fairly straightforward and the new unit came with all the necessary parts already attached, with a new pressure switch in the box as well. Of course, this was just in time to close the pool for the season, but I'm very happy to know it is ready to start up in the spring!