How to calculate the wattage needed

[Scott Sperbeck]

I have a project in which a client is wanting an outside glass deck floor to be heated to keep from freezing. Below the floor is ambient temperatures. The glass is 1.25 ( 3 layers of 3/8" with a /060 inter-layer between each lite of glass) thick each panel is 30" x 60". I don't want to overpower the units as if we can get away without a control unit it would be much easier as there is over 30 panels. Also we want to watch the total amperage draw.

 

[berkeman]

I have a project in which a client is wanting an outside glass deck floor to be heated to keep from freezing. Below the floor is ambient temperatures. The glass is 1.25 ( 3 layers of 3/8" with a /060 inter-layer between each lite of glass) thick each panel is 30" x 60". I don't want to overpower the units as if we can get away without a control unit it would be much easier as there is over 30 panels. Also we want to watch the total amperage draw.

Welcome to the PF.

Glass is generally a thermal insulator. How do you propose to heat it?

 

[Scott Sperbeck]

The same we make electrically heated windows, ITO.

 

[berkeman]

The same we make electrically heated windows, ITO.

Yes, looking at your website I see it's commonly done. You'll put the ITO between each of the 3 glass layers in this project? You said the air below the deck is ambient temperature, but the deck is also outdoors? What will the ambient temperature be in the space above the deck? Whatever it is heated to by the floor panels? Are the sides of the deck open to ambient too, or is there some sort of siding?

 

[Bystander]

"Ambient?" Where?

 

[Scott Sperbeck]

Just received updated information. The glass floor will now be enclosed both above and below the floor. They are looking just to keep the glass warm in the winter months. Is there a calculation that can be used?

 

[berkeman]

Just received updated information. The glass floor will now be enclosed both above and below the floor. They are looking just to keep the glass warm in the winter months. Is there a calculation that can be used?

If the floor is now enclosed, why is it glass? Sorry, I'm not tracking what you're saying very well.

If it's just a heated floor, you would look at air exchange for the room and insulation for the walls and floor...

 

[Scott Sperbeck]

Originally, the floor was part of an outdoor balcony. It is now an indoor room with an indoor room below, thus the meaning "enclosed". I'm looking for the calculation to know how warm the glass will get. The known parameters are: Glass: 3 layers of laminated 3/8" with .060" interlayers for a thickness of 1.25". The glass is coated with ITO and has a sheet resistance of 15 ohms. Glass size is 30" x 60" total weight is 190 lbs. The ambient air temperature on both sides of the glass will be approximately 70 degrees f.