Calculating equivalent head with in floor

Rankin

I'm a little unfamiliar doing all my own calculations for a job and I need to replace a pump on an in floor system that doesn't appear to be putting out enough volume. When I'm calculating my total head, is the total cumulative of all the loops, or only as big as the greatest restriction.



Example: 1/2" pex at 1.5 GPM creates about 4.99' of head loss for every hundred feet. If I had four loops at 200' would I have a total of 39.92'H (4.99 x 2 x 4) or just 9.98'H (4.99 x 2) ?



Also, I was taught 2 to 4 feet per second is an ideal flow, I know the problems created by having too high of a velocity, but if it's less than that, would that it create too large a ^T?



Thank you, thank you!

Ironman

Head Loss...

Is determined by the longest loop + the manifold, supply & return, any mixing or zone valves, etc. The second half of your example is right. See the link to a recent thread below.







http://www.heatinghelp.com/forum-thread/133286/Calculating-manifold-headloss

Rankin

trigger finger

Guess I should be making better use of this "search" function Dan has given us. Thanks