Insulate with Electric Radiant Thermal Mass Storage Heating Systems?
An engineer has some questions about whether to insulate or not to insulate with electric radiant thermal mass storage heating systems.
He’s wondering how it’s feasible to NOT put insulation between the panels and the ground and thinking the BTUs would be transferring to ground without the insulation.
Do you have any explanation for this or better yet any technical data backing up ThermaRay’s position on this?
Thanks for Asking!
A very good and common question. Hydronic guys will tell you that if you don’t insulate below the tubes, you will lose all that heat to China.
The simple physics of it is that heat can only transfer to a temperature cooler than itself.
- Put your hand on the desk and your heat transfers to the cooler surface.
- Put your hand on a hot cup of coffee and the heat transfers to your hand.
Our heating panels start out at 140 degrees and as heat gets further and further away from the heating panel the medium gets cooler and cooler until it reaches a temperature equal to itself which is the temperature of the earth.
The thermal mass equalizes at about 2’-2-1/2 feet including the concrete and won’t go any further down because the thermostat is satisfied. If you left the heating panels on uncontrolled, you would drive the heat down further and further, but would also heat up the room exponentially as well.
The thermostat being satisfied keeps the thermal mass controlled and releases the heat into the space above as it is needed.
Most power companies won’t allow hydronic systems to be on their Off-Peak programs if they put insulation below the tubes, because they know their won’t be enough thermal mass on the colder days or colder stretches of days and won’t maintain temperature.
Lower Operating Cost
The bottom line is that the larger the Thermal Mass, the lower the operating cost. The smaller the thermal mass, the higher the operating cost.
However, we do have some customers that insist on wasting money on horizontal insulation anyway, but I at least beg them to install it a couple feet down.
Our system will work with horizontal insulation or no insulation below the heating panels, we just like the end user to reap the rewards of lower operating cost. Perimeter vertical insulation is always a must though.
The best answer for maximum effectiveness is not to insulate with electric radiant thermal mass storage heating systems.
In most cases, hydronic systems should place the tubes down in the sand with no insulation either.
Keep in mind, we do recommend insulation below our heating panels under snow/ice melting projects below concrete, pavers or asphalt.
