Fuel Oil Delivery Systems For Dual Fuel Burners - Slant/Fin Caravan LDWO-1100-3-6 Application Manual

Figure 13. Wiring diagram for gravity feed
booster-pump operation
Components usually required are a motorized booster pump
of sufficient capacity, gravity tank and mounting hardware,
automatic oil level pressure switch, vacuum breaker and
necessary check valves and fittings. Additional information
can be obtained from Mitco Manufacturing, Hicksville, New
York.
Duplex booster pumps are desirable to provide standby
capability, in the event of booster pump failure.
Sizing booster pump
To determine the correct size of a booster pump:
a) Using Table 3, find maximum total firing rate of the boiler
system being installed.
b) Find the vertical and horizontal dimensions of the booster
pump's suction line.
c) Make sure the suction line lift and length are with
capabilities of typical booster pumps. Refer to Table 4.
(This data is based on Suntec models BH-1030M at 30
GPH, and BH-1050M at 50 GPH or equivalent.)
NOTE: If lift is excessive (max. "Hg one stage, 15" Hg two
stage), contact pump manufacturer with exact
requirements. If total length is too long, increase suction
line diameter.
d) Using Table 5, find correct supply line size.
Table 4. Maximum booster pump suction line length (1)
Maximum Total Suction Line Lengths (3)
Vertical Firing Rates
Lift (2) up to 30 GPH (5)
0 - 7'
8 - 10'
11 - 13'
14 - 15'
Table 5. Supply line sizes for high-volume fuel oil
delivery systems (7)
Firing Rate
Maximum Total Supply Line Length (8)
Up to 30 GPH (5)
Up to 50 GPH (6)
Supply Line Size 1 ⁄ " O.D. tube
2
1/2" O.D. copper tubing (4)
Firing Rates
up to 50 GPH (6)
100' 63'
80' 53'
63' 41'
52' 34'
300' 800'
175' 350'
1 ⁄ " pipe 3
2
Table 6. Boiler feed line sizes (9)
Total Length
Maximum
25'
75'
200'
(1) Defined as the connection distance between storage tank and inlet of
booster pump.
(2) Height of booster pump inlet above bottom of storage tank. If higher lift is
needed, contact booster pump manufacturer with exact requirements.
(3) Total suction length equals vertical lift plus horizontal distance between
suction line connection at storage tank and inlet of booster pump.
(4) 5/8" tubing allows maximum horizontal distance between supply tank outlet
and booster pump inlet to be safely increased by 250%.
(5) Maximum fuel oil consumption rate with Suntec BH-1030M pump.
(6) Maximum fuel oil consumption rate with Suntec BH-1050M pump.
(7) Supply line is defined as the connection between the outlet of the booster
pump and the inlet of the supply tank.
(8) Total supply line length equals vertical lift plus horizontal distance between
booster pump outlet and supply tank inlet.
(9) Boiler feed line is defined as the connection between the gravity feed tank
and the furthest burner.
FUEL OIL DELIVERY SYSTEMS
FOR DUAL FUEL BURNERS
GENERAL
Dual fuel burners are shipped separately and must be field
mounted and wired. Connections to Slant/Fin control systems
can be found in the control section of this manual.
Burner set-up and mounting instructions are shipped with
each dual fuel burner. The installer must follow these
instructions.
Dual fuel burners require specific types of fuel oil piping
systems. The fuel oil pump is active during gas and oil
operation. Since no oil flows to the burner during gas
operation, a two pipe system keeps fuel oil in circulation,
preventing pump overheating and thermal expansion.
Figures 14 and 15 illustrate two types of two pipe fuel oil
delivery systems for dual fuel burners.
If the system is gravity feed, or if the lift is 12' or less, a single
stage pump may be selected. If the lift is 18' or less, then a
two stage fuel pump should be used. If the lift is more than
18', use a pseudo two pipe loop system (Figure 15).
TWO PIPE SYSTEM (Figure 14)
An important factor to consider in a two pipe system is the
line size which depends on the maximum line length and the
total oil volume. The gear capacity of the pump is normally
quite high compared to the pump's marked capacity. For
example, an "A" pump marked for 3 GPH could have a gear
capacity of 17 GPH at 3450 RPM.
For a Caravan system, it is ideal to have individual supply and
return fuel lines for each boiler. In practice, one can opt to
have not more than 3 boilers on a single supply or suction line
and a common return for 6 to 9 boilers . (Figure 14)
Table 8 is the calculated line lengths for two types of "B"
pumps with different gear capacities. For example, if the lift is
2500'
10', the furthest boiler 150' and the fuel oil pump is two stage,
1500'
of type B89 series, then the corresponding line length from
⁄ " pipe
the table is 161' for 5/8" tubing.
4
11
Firing Rates Firing Rates
up to 30 GPH (5) up to 50 GPH (6)
1 ⁄ " O.D. tube 1 ⁄ " O.D. tube
2 2
1 ⁄ " pipe
2
⁄ " pipe
3
4
1 ⁄ " pipe
2
⁄ " pipe
3
4