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How fast can you or should you raise the temperature of your driveway?
If you raise the temperature too fast will it cause concrete to crack?
If you start out with 30 degrees return and three hours later up to 65 is that fast?
Was mention to me that snow/ice sensor 090 is made to protect the concrete.
keeps from raising the temperature too fast.
How fast is to fast?
Does anyone know?
If you good point me to any literature on the subject that would be great
Thanks
@hot_rod thanks for your prior post on the gutter sensor
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Comments
Unless you're dumping a tremendous amount of btu's into it, like a hospital heli-pad, designed to melt and dry the slab. But usually they keep their slabs idling.
ASHRAE indicates Class 2 around 125- 250 btu/ft. typically
Class 3 as 250- 450 btu/ft
Maybe Gordy or some of the concrete chat rooms have data on slab expansion concerns.
Good snow detectors will watch and limit temperature mainly to keep the slab just warm enough to melt. Excessive temperature just increases fuel cost. Good controls can watch ∆T also to prevent over-heating. The best, most accurate control is a well placed tekmar, HBX type SIM detector.
Generally SWT is below 140F to get the job done. Tighter tube spacing can provide lower operating SWT and provide n even melt surface, also. Wind speed can have a big effect on the loads.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
If proper expansion joints, and contraction cuts were installed when the slab was done shouldn’t be any issues.
A rough scenario was this last polar vortex. 70 degree temp cycle with out snow melt. Insulated snow melt slabs are not utilizing much of the grounds heat to help that slab. Slabs going to reflect the ambient temps more. Temps were in the 20’s We got considerable snow so the snow melt would have been active if you had one. The temps dropped to -25 . So shut down, and slab cooling would have been brutal.
Most times the issues are under performing systems rather than over performing.
Remember you have a slab mass that is in an unconditioned space sucking the btus right out of it from the air / slab delta alone. I highly doubt unless you were to really try by oversizing everything you could create a scenario that would cause damage.
Think of it this way the abuse from plowing, and salting concrete is far more damaging than slab expansion, and contraction. So the snow melt actually saves concrete damage.
Unless you have huge BTU/ft ratios, I don't think you will crack a slab if you keep the water temps where they belong <130 degrees. Lower is better both for even melting and longevity.
Albert Einstein
Albert Einstein