pasive solar heat

Hi Joanne,
Sounds like an interesting problem. The fact that you can get 90deg+ temperatures during the day are great. You did not say if you had a floor capable of storing that heat in storage capacity. If your intend to store heat in a liquid like water as Mo suggested, I believe you would more than likely have to have a somewhat large storage capacity.

 Twenty yrs. back when I looked into solar, people were using multiple 12"-18" diameter plastic heavy duty tubes about 6' tall to store water as heat. The big problem then was the water would get slimy because it was standing idle. Also you would have to make sure it was in a place where it would not get knocked over, since the tops of the tubes are open.
Using small containers would require multiple containers practically covering the floor area to get the storage needed. And you still have to move the stored heat some how.
How about having installed a duct through the wall at the highest point in the room that you want to heat, to move a maximun amount of heat out of the sun room and into the house during the day. A blower motor that could be thermostally controlled could control when it would be operating with the temperature of the sun room. A damper on the duct on the inside room would help to prevent cool air from falling into the room when the sum room temperature was not warm enough. If you closed the sliding door with the blower fan running you will need a return duct at floor level the same size as the supply to keep air moving. This duct will need a damper on it as well to prevent cool air from returning to the room when the system is not running.
Unfortunately you may not be able to heat to house completely at night but I would definitely get as much of that free heat that you could during the day to lower you fuel bills. Hope this info is helpful.
Jack

 

Joann;
  I'm just going to reiterate what others are saying, but moreso.

1) Thermal Mass for storage.  Water has a great energy density, as others have said.  Also popular is a 'Trombe Wall', if your FLOOR can handle it.  If the floor or the North Wall areas could be given a thick layer of Bricks, Adobe, Concrete, Sand... or if you could make brickstacks/towers that doubled as shelving, they would hold some heat in them.  Ideally, the collecting mass needs to be getting the sun directly.  The transfer from ambient air temps will be less.

2) Good air-cycling vents and fans would let the rest of the house serve this storage purpose as well. (To some extent, you are 'storing' the heat in fuel NOT burned during the day, that would later be spent keeping the Solar room warmed at night)  Having vent access the top and bottom of the sunroom would be very helpful at extracting the majority of the accumulated heat.

3)  Definitely cover the glass.  There are Quilt/curtain materials that roll out like shades and cover from the inside.  They can be on rails that keep the air from 'Thermo-siphoning' through and around the glass and back into the space.  With internal insulating, it is important to prevent the glazing from overheating once the sun rises, though.  We've had Panes crack in the heat, when Foam panels were fitted inside windows at night, though they WERE faced with black paper, so the gap became a solar oven fast in the morning.

  Another insulator you might consider is creating lightweight Foam Insulation 'Shutters' on the outside.  It would take some careful thought to Deploy and Retract them without too much fussing, but could have signifigant Heat saving potential for that room.  I like the foil-lined 'PolyIsoCyanurate' foam boards for constructing insulation projects, though it could be an insulated 'Quilt' of Tarp or Awning Fabric over layers of what-you-will..  if you will.

By the way,  I HIGHLY recommend putting insulated curtains on all your windows, and make them easy to open/close, so they actually get used.  Windows throw away a TON of your precious heat! Even the good, insulated ones.

Bob Fiske
Portland, Maine