Delta T question

Peddler

What's the recommended Delta t for in-slab radiant systems? Supply water vs return water?

KCA_2

A larger DT

Has more BTU's associated with it. In other words, 20deg DT @ 1 GPM has 10MBTU off into the space. @ 10deg DT there is only 5MBTU and a 30deg.. Well..

The issues are: design & comfort. I like to use a 10deg DT if I'm able and if the design allows (a lower DT means more tube, in most cases). 10deg across the floor (tile especially) is less detectable to the feet than a 20deg. But I think most guys utilize a 20deg DT.

:-) Kca

Dave H_2

Water Temp Drop

It can vary depending upon the project.

Residentailly I like to design 10-15 degree drop. That keeps the floor surface temps even and eliminates temperature "streaking" across the floors.

For snow melting, I like to use a 30 degree drop, keeps your circulator sizing down to a minumum. The same also applies for commercial radiant floors, longer loops, higher temp drops.

Dave H.