flow rates for radiant

ed m

trying to see what to set my flow rates on manifold, 5 loops 1/2 pex at approx. 250ft per loop. for radiant in floor heat off an indirect.
thanks
eddie

Brad White_201

Some variables need to be nailed down.

Hi Eddie,

It all starts with your heat loss (of course!), but also your floor covering R-value and net radiant area. Also, is it a slab, sub-floor panels, what now?

A short answer would say that 0.5 to 0.75 GPM per circuit is a reasonable flow rate range, but what temperature drop?

Some designers prefer a 10 degree temperature drop to reduce temperature contrast, some go 20 and have no issues.

By the basis I give above, you could supply between 18,750 and 37,500 BTUH and if a maximum density of 30 BTUH per SF, 625 to 1,250 SF of radiated floor area.

Too much of a range to give you the real answer which is probably something else...

Josh_10

Hey Eddie,

Here is a Radiant Panel Worksheet I made for this purpose.

Might help you..