Thermal Break between Radiant Zones

CDM2

How critical is providing a thermal break between radiant floor zones in a high mass concrete slab on grade? I had been taught that if you wanted to maintain different temperatures between radiant zones (in a basement for example) you should provide a thermal break, such as expansion joint material; otherwise it would not make sense to have multiple zones/ multiple temperatures as the warmer zone will migrate to the lower temp zone, defeating the purpose of zoning. Any thoughts?

Brad White

Pretty much

what you said. If I have a concrete slab design, say a basement as they tend to be, making the zone boundaries the same as the expansion joints is a good practice. Concrete is pretty conductive and we all know how that mass can get away from you.



If you have spaces with distinctly different floor coverings (hence

different water temperatures), dividing these pours will be a solid

investment in control.



A dominant zone without the break will eventually migrate to adjacent zones which use a lower water temperature, say a wood floor or carpeted living room next to a tiled entry way or bathroom or kitchen.



Normally this is not a problem if the spaces use the same temperature (assuming the same floor covering).  In these design cases, most folks do not try to keep different temperatures anyway; too hard to control and response time is slow as it is.





My $0.02



Brad