Q: I have a pentair 400 heater. It has been making a knocking sound like their is a rock hitting . I know it is not air. It still heats but when it starts it knock I turn it off. Read More …
Q: I have a pentair 400 heater. It has been making a knocking sound like their is a rock hitting . I know it is not air. It still heats but when it starts it knock I turn it off. Read More …