HEKI Sun Protection & Reflectix
Looking for expert opinions on how to best protect the inside of my new (used) Northstar camper from the intense heat of summer. I've got a big HEKI hatch over the bed, and have drawn the dark scre...
Forum Discussion
covered wagon etc,
Ever wonder why a vaccuum bottle like the Dewar or Thermos is coated with a shiny silver coating on both outside surfaces of the glass bottle within a glass bottle? You can prove the reason to yourself by placing a wide mouth clear pint Mason Jar filled with room temp water and capped inside a clear quart Mason Jar with dehumidified air blowing in it and then capping it thus creating a dead air space and next setting it outside in the bright sun for an hour or so. Open both lars and use a thermometer to check the water temp in the pint jar and write it down.
Now wrap the total outside of the quart jar with aluminum foil with the shiny side out and the pint jar outside with the shiny side in and repeat the same test. If the cap is painted dark, spread some foil over it or a white piece of paper double stick taped on for both tests as dark absorbs heat and solar rays.
You will see a big difference in the water temps in the pint jar. Which jar type would you want as your RV in the summer sun? Radiant heat and rays are very powerful. However, they can't pass thru the aluminum foil and are reflected back away from both shiny sides. You can do the same experiment using ice cubes or boiling water in the pint jar and checking the pint jar temps after equal time in the sun or your freezer.
Copied and pasted for some info:
A vacuum flask (also known as a Dewar flask, Dewar bottle or Thermos) is an insulating storage vessel that greatly lengthens the time over which its contents remain hotter or cooler than the flask's surroundings. Invented by Sir James Dewar in 1892, the vacuum flask consists of two flasks, placed one within the other and joined at the neck. The gap between the two flasks is partially evacuated of air, creating a near-vacuum which prevents heat transfer by conduction or convection.
Assuming that the outer surface of the inner wall and the inner surface of the outer wall of the vacuum flask are coated with polished silver to minimize heat loss due to radiation, we can say that the rate of heat absorption by the inner surface of the outer wall is equal to the absorptivity of polished silver times the heat radiated by the outer surface of the inner wall.
In order for energy balance to be maintained, the heat lost through the outer surface of the outer wall must be equal to the heat absorbed by the inner surface of the outer wall. The absorptivity of polished silver is the same as its emissivity.
The glass of the vacuum bottle is a true moisture barrier and the silver coating reflects the radiant energy. Notice the dead air chamber between the two bottles is sealed so no air can circulate or infiltrate? That's what you want in your RV and home also in the insulation areas. The only thing you are missing is a created vacuum in your RV and home insulation chambers however, You can help this missing factor greatly by keeping the humidity level as low as possible on the side you can control. Moisture (dispersed water mist or molecules) in air conducts thermals so much better than drier air does. A/C is a golden example as it's first a dehumidifier and then a refrigerated cooler. What does it remove from the air? WATER!
The whys of shiny 2 sided bubble wraps and proper instalation and sealing and what they do.
Guess I've carried on far too long now!
Ever wonder why a vaccuum bottle like the Dewar or Thermos is coated with a shiny silver coating on both outside surfaces of the glass bottle within a glass bottle? You can prove the reason to yourself by placing a wide mouth clear pint Mason Jar filled with room temp water and capped inside a clear quart Mason Jar with dehumidified air blowing in it and then capping it thus creating a dead air space and next setting it outside in the bright sun for an hour or so. Open both lars and use a thermometer to check the water temp in the pint jar and write it down.
Now wrap the total outside of the quart jar with aluminum foil with the shiny side out and the pint jar outside with the shiny side in and repeat the same test. If the cap is painted dark, spread some foil over it or a white piece of paper double stick taped on for both tests as dark absorbs heat and solar rays.
You will see a big difference in the water temps in the pint jar. Which jar type would you want as your RV in the summer sun? Radiant heat and rays are very powerful. However, they can't pass thru the aluminum foil and are reflected back away from both shiny sides. You can do the same experiment using ice cubes or boiling water in the pint jar and checking the pint jar temps after equal time in the sun or your freezer.
Copied and pasted for some info:
A vacuum flask (also known as a Dewar flask, Dewar bottle or Thermos) is an insulating storage vessel that greatly lengthens the time over which its contents remain hotter or cooler than the flask's surroundings. Invented by Sir James Dewar in 1892, the vacuum flask consists of two flasks, placed one within the other and joined at the neck. The gap between the two flasks is partially evacuated of air, creating a near-vacuum which prevents heat transfer by conduction or convection.
Assuming that the outer surface of the inner wall and the inner surface of the outer wall of the vacuum flask are coated with polished silver to minimize heat loss due to radiation, we can say that the rate of heat absorption by the inner surface of the outer wall is equal to the absorptivity of polished silver times the heat radiated by the outer surface of the inner wall.
In order for energy balance to be maintained, the heat lost through the outer surface of the outer wall must be equal to the heat absorbed by the inner surface of the outer wall. The absorptivity of polished silver is the same as its emissivity.
The glass of the vacuum bottle is a true moisture barrier and the silver coating reflects the radiant energy. Notice the dead air chamber between the two bottles is sealed so no air can circulate or infiltrate? That's what you want in your RV and home also in the insulation areas. The only thing you are missing is a created vacuum in your RV and home insulation chambers however, You can help this missing factor greatly by keeping the humidity level as low as possible on the side you can control. Moisture (dispersed water mist or molecules) in air conducts thermals so much better than drier air does. A/C is a golden example as it's first a dehumidifier and then a refrigerated cooler. What does it remove from the air? WATER!
The whys of shiny 2 sided bubble wraps and proper instalation and sealing and what they do.
Guess I've carried on far too long now!
