Radiant flow rate

George Peteya_4

... and assuming 3 feet of head loss in supply and return piping, about 2.5 gpm.

Bernie Riddle_2

How many gallons per minute

In a radiant floor with 5 runs of 1/2 pex 300 ft. long on 12 inch centers, 007 pump?

ALH_4

flow

It depends on the glycol concentration and any distribution piping and valves, but you are *probably* around 0.5gpm for each loop with 30% glycol if everything is wide open. The 007 curve is pretty flat at that point, so a small head difference makes a big flow difference.

Bernie Riddle_2

Should have added

4 ft of head from main boiler loop and a taco 5000 series mixing valve between boiler loop and circulator, no glycol just straight water.

ALH_4

wider dT

The valve probably adds another foot or so of loss. You are looking at some pretty low flow rates and therefore pretty wide dT. I'm guessing at a 40°F temperature drop to move the required btu. This means higher supply temperatures and a floor that is probably somewhat less even depending on the tube layout. A 008 would be a better circulator for this system. I am assuming this is in a slab of some sort due to the 12" spacing.

George Peteya_3

Sorry ...

... disregard the earlier post. Should have been 4 gpm. Now you're around 3.5.

Bernie Riddle_2

Yep your right on the money Andrew. It is a 4 inch slab, and has a wide delta T (can never get the return temps much above the actual temp of the concrete) and cold spots that annoy the heck out of me.

You mention the 008 to increase the flow. Based on the info I have provided how much more flow would the 008 give me?

Thanks for the quick responses guys!

George Peteya_3

You'll get ...

... 4.5 gpm.

Bernie Riddle_2

Would half a gallon a minute distributed between the 5 300 ft loops make much of a difference?

I have a 011 and I would imagine that bad boy would be the other extreme....Unless I restricted it with the ball valve on the outlet side.

ALH_4

more flow

A 0011 is way too much. I'm not sure where the 4ft of head loss from the distribution piping comes from. It will vary with flow rate. I'm guessing a little here, but I would say you should be able to *approximately* double the flow rate with the 008. Another option is a Grundfos UP15-58FC. You can compare the curves for yourself if you like.