8
CAPACITY AND FLOW DATA
TABLE 3. RECOVERY CAPACITIES
Model
No.
Input
Rating
(Btu/hr)
Output
Rating
(Btu/hr)
Water
Flow
Temperature Rise - ΔT °F (°C)
20
40
60
80
90
100
120
140
(11)
(22)
(33)
(44)
(50)
(56)
(67)
(78)
VW-1500
1,500,000
1,260,000
GPH
7,560
3,780
2,520
1,890
1,680
1,512
1,260
1,080
LPH
28,615
14,307
9,538
7,154
6,359
5,723
4,769
4,088
VW-2000
2,000,000
1,680,000
GPH
10,080
5,040
3,360
2,520
2,240
2,016
1,680
1,440
LPH
38,153
19,076
12,718
9,538
8,478
7,631
6,359
5,450
THE CONTROL SYSTEM
The control system consists of 5 basic components:
1)The Modulation control board (MCB) 2) The Power distribution board
(PDB) 3) Blocked Inlet Pressure Switch (BIS) 4) Blower Prover Switch
(BPS) 5) Blocked Flue Switch (BFS). See Figure 2. The Modulation
Control Board is located in the control box and can be accessed
by opening the front door of the unit. The User Interface Module is
attached to the front door panel. Every system will have one Modulation
Control Board (MCB), one Power Distribution Board (PDB), and one
User Interface Module (UIM).
The MCB contains dipswitches which are used to configure the boiler
for several different control options, see the Control System Section.
FIGURE 2.
HOT SURFACE IGNITER
The Hot Surface Igniter is a device that ignites the main burner, see
Figure 3. When 120 VAC is applied to the igniter, suf fi cient heat is
generated to ignite the main burner. Although improvements have
been made to strength en the igniter, it is still fragile and care must
be taken in handling the igniter to prevent breakage.
FIGURE 3.
PRESSURE SWITCHES
This control system has 3 pressure switches that are standard. Blocked
Inlet Pressure Switch (BIS), Blower Prover Switch (BPS) Blocked
Flue Switch (BFS).
The BPS on this model is a normally open switch that closes on
increased vacuum. Once the blower moves enough air to create a
vacuum across the Venturi the BPS is activated. If the blower fails
or cannot move sufficient air a soft lockout will occur. Inspect the
blower for correct operation.
The Blocked Inlet Switch (BIS) will activate is the intake is blocked
only during the heating cycle. The BIS is a normally closed pressure
switch that opens when the air intake is blocked. If the BIS is activated
check and clear the intake of any obstructions.
The blocked flue pressure switch (BFS) activated when the exhaust
flue of the unit is restricted or blocked. The BFS is a normally closed
switch that opens when positive pressure is placed on the switch
because of any restriction to the exhaust venting. If the BFS is activated
check and clear any obstructions causing the restriction.
FIGURE 4.
CONTROL COMPONENTS