permeable pavers

john walsh

Hello, I am a heating contractor in Mass. and I am doing a snowmelt system under semi permeable pavers. There is about six inches of stone under these to allow for drainage so there is no real way to install insulation. I am also worried about melting snow scrubbing away heat from the slab. Does anyone have any exp. with these or can suggest a btu per ft. that might work. JW.

Unknown

small gravel??

John,

I have had great success with systems like this in my area with pavers on compressed sand.

I'm more worried about the ston puncturing the tube and having enough contact for heat transfer. I hope you are putting the tube in sand or shavings.

Once the system starts melting the water will increase the heat transfer. One you have the snow off the BTU need will increase because of solar gain (you are trying to heat Mars at that point.. unless it's real cloudy.

I have always used 0 degress with a 10mph wind with avergae snow fall sending supply water temp out at 138F with a 35DeltaT using 147 btu/sq foot, reverse return with tube at 10" OC.


skw

Dave_4

I do know this.

The concern is NOT what's lost to the sub-base. The problem must be understood; that being - getting the surface to 34F - NOT human comfort!

Unless the job is in The Yukon, it snows a few days a year. If not melted, snow does hang around for weeks. Do not confuse the presence of fallen snow with the actual event you must deal with. We need not "heat" the pavers per se, merely get snow to melt. When temps drop to single digits, it rarely snows. Sensors are key to a good snow-melt app.

Further, there will be no "drainage" if there's no snow to fire up the melt system for, and if rain comes while the ground/gravel bed is already saturated and below freezing - the air at 35 and rain drools through the joints and filters into the sub-freezing base. At that point, the gravel voids will be a block of ice.

Designing the system to thaw ice below the pavers may be a reqirement. Ever seen frost heaves under pavers? True, they return almost to dead flat after a spring thaw, but the uneven edges are the stuff chips are spawned from, should the melt system have no snow, but ice within the base gravel.

Further, any heat put into the sand, paver or gravel will leave via the paver surface. Residual heat in the graduations of whatever's under the pavers is not lost, merely present in varying degrees of emmission, nased on all the variables you already understand.

Is there anything specifically that you have concerns over?



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