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1947-48 Theatre Catalog, 6th Edition, Page 423 (409)

1947-48 Theatre Catalog, 6th Edition
1947-48 Theatre Catalog
1947-48 Theatre Catalog, 6th Edition, Page 423
Page 423

1947-48 Theatre Catalog, 6th Edition, Page 423

in the form on a bank of 84 1,500-watt electric tungsten lamps is situated 10 feet above the cover glass of the heat collection chamber, and interposed between the source and the cover glass is a sheet of double strength window glass which absorbs the excess infra-red radiation, so that the radiation impinging on the collection plates more nearly approximate that from the sun.

The heat collection chamber described makes up a length of 6 feet of the total length of the indoor unit.

The heated air leaving the heat collection chamber passes to a tapered exit section which is well insulated against radiant heat. (Compare with Figure 3.)

To make a run on the indoor unit, the independent variables are chosen and the unit is set in operation. These variables are spacing between plates, length of plate overlap, entrance air temperature, and air velocity. When equilibrium is reached, as shown by the attainment of constant temperatures, the run is discontinued, and a new set of independent variables is chosen. At equilibrium the following readings are taken: (1) air velocity, (2) entrance air temperature, (3) exit air temperature, (4) temperature of air leaving black surfaces of two plates near the center of the stack, (5) temperature of air leaving black surfaces of bottom and second plates, (6) temperature of air passing through rotameter, (7) surface temperature in center of blackened portion of central plate in stack (bottom plate temperature), (8) surface temperature three inches behind leading edge of central plate in stack (top plate temperature), and (9) cover plate temperature, under side. From these data, it is possible to calculate the ehiciency of heat recovery if the heat input from the lamp bank is known.

The important conclusions of the tests on the indoor unit (Figure 2) were (1) the general principle of the heat collector as set forth by K. W. Miller was shown to be workable, (2) the optimum plate spacing was found to be 1.; inch, and (3) the optimum plate overlap was found to be 2/3. The plate length factor was not investigated thoroughly enough to draw any definite conclusions, but it is believed that a variation in plate length would not materially affect the operating characteristiCS of the unit, all other factors being constant.

Experimental House Unif

The experimental house unit was constructed on the roof of the home of Dr. G. 0. G. Lof, at 1719 Mariposa Street, Boulder, Colorado. Figure 4 illustrates the construction of the unit.

Lying on the slope of the roof are 16 supports constructed of 2x6-inch lumber, supported and separated by iron strips which also act as supports for the cover glass. In the sides of these pieces are cut appropriate slots into which are driven narrow strips of composition board; the slots and strips are positioned so that they will support the glass plates in their proper relation. At the end of each strip is fastened a small wood block which prevents the glass plates from sliding down the roof. The assembly is built directly on top of the shingles of the roof; but before the glass is laid, a 1.5-inch layer of Celotex insulation is placed over the shingles.


The supports are spaced on 32-inch centors and the glass plates are 30 inches wide by 36 inches long. The glass plates are placed in the optimum arrangement found in the tests on the outdoor unit which was found to be 14-inch spacing, 2/3 overlap, with 12 inches of each plate painted black. The cover glasses are put in place in grooves cut in the top side of the supports and sealed with putty; the ends on the cover glasses overlap in the manner of a greenhouse glazing. A cap strip of sheet metal is placed on the top edge of each 2x6 to protect the seal from weathering. A flashing made of sheet metal covers the top and bottom ends of the unit.

The entrance air inlet is cut through the roof at the bottom end of the unit and a duct is built from the house cold air return to these openings in the roof. The heated air is drawn from the top of the unit through similar holes cut in the roof. The duct system employed for the hot air is shown in Figure 4, and consists of a large duct leading from the hot air outlets of the unit to the center of the attic where it branches into two. One branch leads to the bottom of the furnace and thence to the fan and into the hot air circulation system. The other branch leads through a finned tube water heater and thence to a natural circulation vent through the roof, the top of which is higher than the top of the solar unit. The finned tube heater is used to heat water when the heat is not needed to heat the house. This heated water is stored in a 120gallon tank installed in the attic, as shown in the drawing. This tank is connected directly to the inlet of the automatic hot water heater.

Installed in this duct system are suitable controls in the form of thermos stats, dampers, damper motors, and relays which permit the unit to be operated in the following manner automatically: >

Case IeHouse is cold, solar unit is cold. The automatic gas furnace heats the house in the normal manner.

Case lI-House is cold, solar unit is hot. The hot air from the unit goes directly to the furnace inlet and is blown by the furnace fan to the house heating system; the cold air return is routed back to the bottom of the solar unit.

Case III-House is hot, solar unit is cold. Heating not necessary, therefore dampers are closed and furnace not operating.

Case IV-House is hot, solar unit is hot. The hot air from the unit is vented through the natural draft vent after passing through the finned tube water heater.

Before the unit was placed in operation, the exit air temperature from each section was set at the same value by adjusting the air flow in the sections with dampers at the outlet of each section. The temperatures were measured by iron-constantan thermocouples.

It was found necessary or desirable to prevent breakage during the hail season by covering the solar heat collecting unit with a suitable screen. A galvanized iron screen with 1[1-inch openings was used. This screen was supported on strips of wood 2x2 inches, fastened on top of each 2x6.

It was found that no protection from snow was necessary, since the tilt of the roof and the smoothness of the glass aIIOWed the snow to slide readily off the unit (Figure 5).

By preliminary calculations and observations, it is found that the installation of the unit of 463 square feet on the roof of this house will furnish approximately 33 percent of the heating load required by the house for an entire winter if no storage facilities are available. Further calculations were made to show the advantage of a suitable storage unit for the storage of heat for one-, two-, and three-day periods. These calculations were based on the heat required during the previous year per degree-day of heating load, which was determined from gas-meter readings and degreesday figures procured from the Public Service Company.

FIGURE 3-The laboratory (experimental) unit was built to check. under outdoor conditions. the principles learned from the indoor model. This unit, however, is no longer used. having been superseded by the house unit designed and tested under actual operating conditions in Boulder. Colorado. It is, then. a transitional model between that of Figures 1 and 2 and of Figures 4 and 5.

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1947-48 Theatre Catalog, 6th Edition, Page 423