Delta T on Radiant Loop

Ericjeeper

I see the low delta T as a benefit.. the returning water only has to pick up 5 degrees from the heat exchanger before it returns to the loops. Not then the floor temps will be more even as they come up to temps. If you slow the flow down you will heat the first part of the loop up first, and then when the water gets back to the HE it has to pick up more heat.. Causing boiler to fire. I would rather have a banked up evenly slab rather than a hp edge . Just my .02
as for a variable speed no.. Just use some valves to slow the flow down a bit to a particular loop. for instance the one that heats up the fastest

van_5

Low Delta T on Radiant Loop

I am trying to decide if a radiant loop that sometimes has a low supply/return delta T is a problem and if so, how can I fix it. On a day like today, 47* outside, RTU set for 67* room temp. Supply temp to loop is 90* and return is 85*. Would think that you would like to "loose" more of the heat to the room. On colder days, this zone has a higher delta T but not that much higher. The radiant zone consists of 6 loops of 1/2" PEX into Wirsbro manifolds and a 007 pumping to the manifold. Each of the loops is 180' to 240' long.

I would think that slowing the flow of water through the loops would create more delta T. Would that argue for a smaller pump? (I have tried to simulate lower flow by slightly closing the ball valve on the suction side of the circ but that did not seem to make too much of a difference and I was hesitant of closing the valve too far.) Is there anyway to make the 007 variable speed just like you do with an injection pump and vary the speed based on the difference between the supply and return temp? Does anybody make a variable speed controller for these small Tacos?