Johnson-level-tool-mfg RAS-1 Manuel d'utilisateur télécharger pdf (Page 36)

TABLE B

Change Decimals to Fractions

.06" =1/16" .56" =9/16"

.13" =1/8" .63" =5/8"

.19" =3/16" .69" =11/16"

.25" =1/4" .75" =3/4"

.31" =5/16" .81" =13/16"

.38" =3/8" .88" =7/8"

.44" =7/16" .94"=15/16"

.50" =1/2"

SOLAR PANEL SUPPORT EXAMPLE

Let us build a rafter support for a series of ﬂat plate

collectorsonasouth-facing8-inchriseroof.

STEP 1. RAFTER CALCULATIONS: The pitch for the

support rafters, which is really the desired tilt angle for

the solar panels, will be needed. If known in degrees,

convert it to the nearest inch rise so that the tables may

beused.Thispitchisfoundbyadding10to15degrees

toyourlatitude(sincethisistheoreticallythebestfor

heating).Inourexample,weneeda58°pitchora19

inchrisebecausethelatitudeofMilwaukeeis43°.(See

Table C, page 39). The angle of tilt is not critical, since

the eciency is not appreciably reduced by a small dif-

ference in tilt angle from optimum, thus the closest inch

risecanbeused(seeFigures20and21).

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Johnson-level-tool-mfg RAS-1 Manuel d'utilisateur Page 36