info required re air heating in the roof space

[staergaezer]

Hi there. I have an idea about increasing the temperature in my roof space during winter and then by using fans have this warm/hot air blown down into the house. I figure that if I can raise the temperature in the house by about 5 degrees C I will save a lot on space heaters. I have a large very well insulated roof space with the ceiling topped with pink aerolite as well flock. There is sisalation under the roof tiles, My question/problem is this....I am pretty sure that if I fir several panels of black painted glass into the roof I will get a pretty good increase in the roof space temperature but how do stop the outward radiation at night time? Question... if I paint the outside black and the inside silver will this do the trick?
Anybody got any ideas?????

Michael

[inetdog]

Question... if I paint the outside black and the inside silver will this do the trick?

NO.

If the reflectivity of the inside of the panel is made high, it will equally decrease both the amount of heated absorbed by it at night and the amount radiated downward during the day.
And it will have no effect at all on conductive/convective heating and cooling.

Adding a lot of thermal mass on side walls (or maybe in the attic) and using some form of shutters to prevent radiation back out at night would be more practical, but I have no idea how well it would actually work.
Whatever you do must not lead to moisture accumulation on top of the ceiling or under the roof at any time of year, or it will cost you more in mold and structural damage than you will gain.

[russ]

A solar air heater would help - especially if you are the DIY type.

[staergaezer]

NO.

If the reflectivity of the inside of the panel is made high, it will equally decrease both the amount of heated absorbed by it at night and the amount radiated downward during the day.
And it will have no effect at all on conductive/convective heating and cooling.

Adding a lot of thermal mass on side walls (or maybe in the attic) and using some form of shutters to prevent radiation back out at night would be more practical, but I have no idea how well it would actually work.
Whatever you do must not lead to moisture accumulation on top of the ceiling or under the roof at any time of year, or it will cost you more in mold and structural damage than you will gain.

Thanks for the info. Guess it wasn't a very good idea after all. Michael

[staergaezer]

A solar air heater would help - especially if you are the DIY type.

I have looked at this but solar air heaters are extremely expensive in South Africa where I am. Thanks anyway for the info. Michael

[inetdog]

I have looked at this but solar air heaters are extremely expensive in South Africa where I am. Thanks anyway for the info. Michael

In this and other forums you will find very practical information on building the entire solar air heating panel yourself, mostly from common materials.
Solar water heating panels are also a DIY possibility, but the air heating panels have the decided advantage for DIY that if they leak a little bit nobody will notice and the performance will not be affected much !

[staergaezer]

In this and other forums you will find very practical information on building the entire solar air heating panel yourself, mostly from common materials.
Solar water heating panels are also a DIY possibility, but the air heating panels have the decided advantage for DIY that if they leak a little bit nobody will notice and the performance will not be affected much !

Hi and thanks but I am a DIY type. Michael

[Naptown]

Hi and thanks but I am a DIY type. Michael

All it takes to make an air heating panel is some glass, aluminum flashing, some framing materials, foam insulation, soda or beer cans, some black paint, some silicone, and some time a small fan, snap switch (thermostat) and basic hand tools.
You could build one for about $40US if you are good at scrounging up materials.

[staergaezer]

All it takes to make an air heating panel is some glass, aluminum flashing, some framing materials, foam insulation, soda or beer cans, some black paint, some silicone, and some time a small fan, snap switch (thermostat) and basic hand tools.
You could build one for about $40US if you are good at scrounging up materials.

Hi there and thanks for the suggestion. My major problem is ....how do I prevent the panel from radiating the heat that has been generated during the day back into the night air.
My basic idea was to use the solar panel to heat the air in the roof space by replacing as many tiles as are necessary with black painted glass panels. The problem being as detailed above.

[Naptown]

Hi there and thanks for the suggestion. My major problem is ....how do I prevent the panel from radiating the heat that has been generated during the day back into the night air.
My basic idea was to use the solar panel to heat the air in the roof space by replacing as many tiles as are necessary with black painted glass panels. The problem being as detailed above.

Read some of the threads in this section that generally does not become a problem and a couple of dampers at worst case would solve that issue.