Installation & Operation Manual
6
DHW prioritization
This piping system is designed to provide direct hot water
priority over the other zones in the heating system. When
there is a Domestic Hot Water (DHW) call for heat, the
Knight control will shut off the boiler circulator and activate
the domestic hot water circulator. Once the DHW demand
is satisfied, the boiler circulator will be readjusted as demand
requires. The circulator must be large enough to move the
boiler water through the coils. The recommended piping for a
DHW priority system is depicted in FIG. 3-3 on page 9.
Multiple tank connections (boiler side)
Multiple tank installations must be done in the “reverse-return”
manner. The reason for this is to create the same pressure drop
(and therefore, the same flow) through the coil of each tank.
The boiler manifold piping must be sized so that each coil has
the flow rate called for in Table 3B.
Because the pressure drop through tank coils varies from size
to size, it is hard to predict the flow rate that will be developed
through each coil when two tanks of different sizes are placed
in the same manifold. For this reason it is best not to mix tanks
of different sizes in the same zone if their recovery is critical.
Table 3B
Pressure Drop Values
MODEL
WATER
INLET
(NPT)
WATER
OUTLET
(NPT)
COIL
CONNECTION
(NPT)
COIL
LENGTH
(FT)
SQ FT
SURFACE
AREA
PRESSURE DROP
(FT/HD)
5
GPM
8
GPM
12
GPM
16
GPM
20
GPM
25
GPM
30
GPM
SIT040
1
1
1
36.5
12.05
0.87
1.99
4.05
6.00
9.89
14.62
20.11
SIT050
1
1
1
36.5
12.05
0.87
1.99
4.05
6.00
9.89
14.62
20.11
SIT065
1.5
1.5
1
44
15.03
0.94
2.14
4.35
7.20
10.64
15.72
21.63
SIT080
1.5
1.5
1
44
15.03
0.94
2.14
4.35
7.20
10.64
15.72
21.63
SIT119
1.5
1.5
1
44
15.03
0.94
2.14
4.35
7.20
10.64
15.72
21.63
3
Boiler side piping
Figures 3-1 thru 3-4 show typical boiler side piping for
several common situations. Regardless of which system is
used it is imperative that the flow rates called for in Table
3B are developed through the coil. This requires properly
sized piping and a properly sized pump.
The system shown in FIG’s 3-1 thru 3-4 are described
below:
Zone with circulator to Aquastat
This system is like the circulator zone system on a straight
heat job except that one of the zones goes to the tank
instead of radiation. As on any circulator zone system
check valves should be installed in each zone to prevent
unwanted circulation through zones which are not calling
for heat. Figure 3-1 on page 7 illustrates typical circulator
zone piping.
Zone with valve to Aquastat
As with the circulator zone system, this system is just like a
standard heating zone system except that one of the zones
is connected to the tank coil as shown in FIG. 3-2. The
system circulator must be large enough to move boiler
water through the coil regardless of the flow rate required
through the heating zones.
Table 3A
Pressure Drop Coil Chart
0
5
10
15
20
25
0
5
10
15
20
25
30
35
Foot Of Head
Flow
Pressure Drop Coil
36.5
44
44'
36.5'
Содержание Squire SIT040DW
Страница 23: ...Notes Installation Operation Manual 23...
