Pump Requirements - RBI FUTERA XLF Series Installation And Operation Instructions Manual

Selection Table (Table 8) and the Pumping
Performance Table (Table 9). Scale free
operation can be achieved by using water
with a hardness between 8 and 18 and by
maintaining the pH between 5 and 9. Follow
the conditions listed under NORMAL
in the table. In some areas of the country
additional precautions must be observed
due to unusual characteristics of the
local water supply. Call the nearest RBI
representative for details.
To properly size the pump a grain hardness
and pH test must be taken at the installation
site before the order is placed. Proper pump
sizing will improve heater performance and
help ensure heater longevity.
Expansion Tank
An expansion tank or other means to control
thermal expansion must be installed in the
water heating system if back fl ow prevention
devices are installed.

Pump Requirements

This low-mass water heater requires a
continuous minimum water flow for
proper operation. The low water flow
switch provided for this unit will shut
down the water heater if fl ow falls below the
required minimum level. Table 9 provides
the heat exchanger pressure drop chart and
temperature rise table. Th e temperature rise
across the water heater must never exceed
35 o F, 19.4 o C.
Cold Water Supply
The cold water supply must be piped to
the water heater's outlet piping between
the water heater and the hot water storage
tank. Th is will prevent untempered water
from entering the water heater. See the
Temperature Rise Control section, page 19.
Two typical water heating systems are
shown in Figures 14 and 15.
20
Finned copper tube gas boilers & water heaters – Boiler Manual F F F d b b l
Table 8 Futera XLF Heat Exchanger Selection
Table 9 Futera XLF Pumping Performance Requirements
Water hardness
Heat exchanger type
Boiler model GPM
MW-2500
MW-3000
MW-3500
or representative)
MW-4000
ΔT = Temperature change = (Outlet temp – Inlet temp) in
ΔP = Head loss = (Inlet pressure – Outlet pressure) in feet of water column
To achieve the proper fl ow rate, adjust outlet valve on heater piping to obtain correct ΔT
Call factory if grains of hardness is less than 3 or greater than 24.
& h B l M
Soft Normal
Cupro-nickel Copper
ΔP ΔT GPM ΔP
SPECIAL 210 9.73
REQUIREMENTS
(Call factory
210 10.40
o F
l
Hard
Cupro-nickel
ΔT GPM ΔP ΔT
25.0 262 14.54 20.0
33.0 262 16.90 27.0