Owner's Manual
35
3.8 RELIEF VALVE—Each Series 8H/8HE module
is supplied with its own pressure relief valve. No
additional relief valves need be installed on the
manifolds. If domestic water heating is added to
a module, it is recommended that a relief valve be
installed as shown in Figure 3-14.
3.9 LIMIT CONTROL—Each Series 8H/8HE module
is supplied with its own high limit control. To meet
ASME requirements, a second operating control must
be placed in the supply header downstream of the last
module but upstream of any valve on the supply main.
The size and type of control well will depend on the
control system selected in Section 5.0. Note: The
local jurisdiction may require that the high limit on the
module be of the manual reset type.
3.10 PRESSURE & TEMPERATURE GAUGE—Each
Series 8H/8HE module is supplied with its own
Tridicator so that the performance of each module can
be observed without installation of additional gauges.
3.11 FILL VALVE—An automatic ll valve is
recommended to maintain the minimum pressure in
the system at the ll pressure required by the height of
the piping system.
3.12 SYSTEM CIRCULATOR—To avoid placing the
head pressure of the system circulator on the boiler
and compression tank, the system circulator should be
installed such that it pumps away from the boiler and
compression tank. See Figures 3-1 and 3-2.
3.13 DOMESTIC WATER HEATING—An external water
heater may be added to any module on either primary-
secondary or parallel circulation system. If heavy
water heating loads are anticipated an additional
module(s) may be added to the water heating circuit.
Refer to Figure 3-14 for recommended module water
piping for domestic water heating, with parallel
piping. Refer to Figure 3-3 for recommended pipng
when using an Alliance Indirect hot water tank with
Primary Secondary Piping.
3.13.1 Water heater size may be determined in the
following manner:
1) From Figure 3-15, nd the appropriate factor for
each xture in the building and add them together
to nd the total xture units.
2) From Figure 3-16, convert the xture units to hot
water capacity in gallons per minute based on 40-
140°F temperature rise.
3) Select water heater based on gallons per minute
from 2) above.
3.13.2 The addition of water heating may not necessarily
add to the size of the modules. Since the maximum
space heating lead and the maximum water heating
load rarely occur at the same time, only a portion of
the water heating load is added to the space heating
load to size the modules as follows:
1) Calculate the water heating load in Btuh:
__________gpm x 8.33 Lb/Gal x 60 Min/Hr x 100
∆T = ___________Btuh
2) Calculate ratio = Water Heating Load
Space Heating Load
3) From Figure 3-17, using the ratio found in 2), nd
factor for sizing the “boiler added capacity”.
4) Calculate “boiler added capacity” by multiplying
factor from 3) by water heating load.
5) Total the space heating load and the “boiler added
capacity”, and convert this total load to total input
by using the 1.44 multiplier from Figure 2-1.
6) Select modules from Figure 2-2 using this total
input.
7) Convert the input of one module (found in Figure
2-3) to Gross Output by using the .80 multiplier
from Figure 2-1.
8) Divide water heating load by gross output of one
module to determine the number of modules to be
used in the water heating circuit.
Example #1—An ofce building has 12 basins and 2
slop sinks and a space heating load of 1,403,500 Btuh.
Size the water heater and boiler.
Solution:
1) 12 basins x ¾ units = 9 Fixture Units
+2 slop sinks x 1½ units = 3 Fixture Units
Total = 12 Fixture Units
2) In Figure 3-16, using curve “C” for ofce building,
nd that for 12 Fixture Units 6 gpm is required.
3) Select water heater at 6 gpm and 40-140°F
temperature rise.
4) Calculate water heating load in Btu.
6 x 8.33 x 60 x 100 = 299,880 Btuh
5) Calculate ratio = Water Heating
Space Heating
= 299,880 = .22
1,403,500
6) From Figure 3-17 nd that for a ratio of less than
.25 the boiler added capacity is 0%.
7) Convert the total load (1,403,500 + 0 Btuh) to total
Input:
1,403,500 Btuh x 1.44 = 2,021 MBH Input
1000 Btuh/MBH
8) Enter Figure 2-2 at 2,046 MBH Input (closest
Input over 2,021 MBH) and select (4) 810HE
modules as the most economical combination of
modules.
9) Convert the Input of one module to Gross Output
using Figures 2-1 and 2-3:
810HE
505 MBH x .80 x 1000 Btuh
MBH
= 406,000 Btuh Gross Output