The manufacturer of the heat pump that we have provides a table in their loop design guide for feet of head loss per 100 feet of various pipe and diameter sizes. Below the table it says: * These head losses are for water at 40 degrees F temperature. After picking out a circulator pump for the current loop design, I considered whether the same pump could be used to flush the loop portion at 2 feet/second. The gallons per minute is just out of range for ft.hd loss table provided, so I searched online and found other tables... which have different (smaller) values (less loss) than the table provided in the design guide for the same pipe to GPM rate. All of the tables I found online were values for 70 degrees F water temperature. This makes sense to me at the moment that when I would be flushing the loop, it would be during the summer months and I could use these online values, as the loop piping should be expanded due to warmer temperatures and have less head loss. None of the tables mention the equation used to compute the values. At https://plasticpipe.org/pdf/chapter06.pdf it mentions the Hazen-Williams method, but there doesn't appear to be a variable for the temperature. I found a remark, elsewhere, that the Hazen-Williams method was good for the water temperature range of 40 to 70 degrees F. What other method is used to figure feet of head loss values in these tables? Should I just use the tables I found online to figure whether the same circulator pump will be able to used during flushing?