Document 02X0VGQdJmVK0J3QrL6pYRjJ
Por tio n
F ig . 5. T ypical' Riser
for 20-Story B u ild in g
HEATINC VENTILATING AIR CONDITIONING GUIDE 1943
Proper air venting of a circulated system is extremely important, particularly if gravity circulation is employed. In Fig.' 6fl and .6b this is
s
c4
X
CO eo
X 04
XX
04 04
XX
04 04
X
04
X
04
XX
04 04
XX
04 04
X
04
XX
04 C4
XX
04 04
X
04 04
1
CO
X
04
X
04
XX
04 04
XX
04 04
X
04
X
04
XX
04 04
XX
04 04
X
04
XX
04 04
XX
04 04
XX
04 04
s eo 04 04 -04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04
to cm CO 04 ' 04 04 04 04 04 04 04 04- 04 04 04 04 04 04 ' 04 04 04 01
g
z
CO 04. 04 04 04 04 04 04 04 04 04 '' 04 04 04 04 04 04 04 04 04
X
04
04
X
XX
XX
X
X
XX
XX
X
XX
XX
XX
os
sa
0.-
z
og d < O3
X
04
04
X
XX
XX
X
X
XX
XX
X
XX
XX
XX
X
04
X
X
XX
XX
X
X
XX
XX
X
XX
XX
XX
04 X X X X X X X X X X X X X X X X X X X
-> o
h a u a
3
C4 X X X X X X X X X X X X X X X X X X X
' 04 X X X X X X X' X X X X X X X X X X X X
a o
' co
XX
** r* r*
_r* *4 44 4* 44 44 -- 44 -- 44 44 44
o o X
U **
. -H 44 -a 44 - 44 44 -- 44 . -a 44 44 44
nDJ Q
* N
X'
** --W
* ' -- . w 44 44 44 -a -a 44 44 ` 44 44
(axo/} X X X X X X X X X X X X X X X X X X X
-- X X X X X X X x -x X X X X X X X X X X
tO ;x X X X X. X X X X X X X X X X X X x. X X
-i* h'-3 -
. *o
j rj <Q mo
s g gCO
. CO
o eo
g
g
o CO
g
o eo
o eo eo
o CO
o CO
g
g
CO
3g
< 0.^
OS
5
t-i Q
O;- a, * `
n4
a;- o. fc. b} Q o BQ
..Bf. ..
soCM ChO i
e St
<*>
*
Gf d
(2
o
4 &>
6 00
AO
an
2 CO
oc
*
SCO*. &a Q O
accomplished, by connecting the circulating line-below the top-fixture supply. .Air is thus, eliminated from the system each time the top fixture is opened. Where an overhead main is located above the highest fixture,
832
CHAPTER 46. WATER SUPPLY PIPING AND WATER.HEATING
as in Fig. 6c an automatic float type air vent is installed at the highest point of the system or a fixture .branch is taken off the top of the main where air venting is desired and then dropped down to the fixture outlet.
The supply riser in Fig. 6o would be sized exactly the same as an upfeed cold water riser. The sizing of Fig. Qb and 6c would- involve calcu lations for both up-feed and down-feed risers. Pressure loss in the overhead main would have to be considered in sizing the up-feed risers.
The return line for a gravity circulating system should never be less than % m- Where supply risers are large or lines are long, larger circu lating lines may be indicated. Pumps are frequently used in large sys tems. to provide positive circulation.
It is sometimes necessary to make an allowance for pressure drop in the
*1
l!
// <a>
\1 [V 1 _
-I a. 1
4 Z--i I I
5
!
g 5r
' CQQ3O.. >
aa3.. <s>
y
. IaQ/3)..
K S1
1 1_______
u* n"
/ (6)
1 l_ \
_. \
,9
/ /s
/f
u>
Fig. 6. Methods of Arranging Hot Water Circulation Lines
heater when sizing hot water lines. This is particularly true where instantaneous heaters are used.
STORAGE CAPACITY AND HEATING LOAD
In estimaiting the" size of hot water storage tank required and the heating capacity to be provided either from the boiler or from an inde pendent domestic-hot water heater, it is necessary to know the total quantity of water to be heated per day, and the maximum amount which will be used in any one hour, as well as the duration of the peak load;
In cases where the requirements for hot water are reasonably uniform, as in residences, apartment buildings, hotels, and the like, smaller storage capacity is required than in the case of factories, schools, office buildings, etc., where practically the entire day's usage of hot water occurs during a very short period. Correspondingly, the heating capacity must be pro portionately greater with uniform usage of hot water than with inter mittent usage where there may be several hours between peak demands during which the water in the storage tank can be brought up-to tempera ture. As a general rule it is desirable to have a large storage capacity in
833