Selecting Equipment - A.O. Smith RXLD-52 Manual

SELECTING EQUIPMENT

The Promax XL heat exchanger systems are rated at "Nominal"
conditions. Their actual performance may vary significantly
based on application. System design should be undertaken only
by technically qualified individuals with an understanding
of pumps, recirculating water piping and heating applications.
These instructions do not cover load sizing or hydronic
heating requirements, but rather provide a means for selecting
the correct side loop water heater and heat exchanger to provide
a specific target heat output.
The RXLD Series is of vented double-wall construction for those
applications where design or local codes require double isolation
between fluid streams. Where applications may have a freeze
potential on the secondary side piping, propylene glycol may
be used to provide freeze protection.
NOTE: Ethylene glycol should not be used.
When selecting equipment for XL applications first compare the
target heating capacity to the listed output for the water heaters.
Prior to purchasing the water heater be sure to confirm water
heater specifications with current literature for the chosen product
PROMAX
SL MODELS
GCVH-40L
GCVT-40L
STANDARD GCVT-50L
VENT GCVX-50L
GCG-65L*
FCG-75L*
XGV-40L
XGV-50L
GCVH-40Q
DYNA- GCVT-40Q
CLEAN II GCVT-50Q
GCVX-50Q
GCG-65Q*
FCG-75Q*
GDVH-40L
DIRECT
GDVH-50L
VENT
GDVH-75L*
GPST-40L
POWER GPST-50L
VENT GPSX-50L
GPST-75L
POWER GPDH-40L
DIRECT GPDT-50L
VENT GPDX-75L
XL
OUTPUT APPLICATIONS
29,600 ALL XL MODELS
35,500 ALL XL MODELS
38,000 ALL XL MODELS
50,050 ALL XL MODELS
49,400 ALL XL MODELS
57,000 ALL XL MODELS
30,400 ALL XL MODELS
32,400 ALL XL MODELS
29,600 ALL XL MODELS
35,500 ALL XL MODELS
38,000 ALL XL MODELS
50,100 ALL XL MODELS
49,400 ALL XL MODELS
60,100 ALL XL MODELS
30,000 RXLS 28 & 52 ONLY
36,000 ALL XL MODELS
41,800 ALL XL MODELS
38,000 ALL XL MODELS
39,900 ALL XL MODELS
47,500 ALL XL MODELS
57,000 ALL XL MODELS
30,400 RXLS 28 & 52 ONLY
47,450 ALL XL MODELS
53,200 ALL XL MODELS
as specifications are subject to change. Next find the target
capacity on the horizontal axis of the heat exchanger
performance tables on page 4. Move vertically on the chart to
find the intersection of the capacity line and desired heat
exchanger outlet water temperature. This is the temperature of
the fluid going to the slab, coil, etc. From this intersection the
flow required for the secondary loop and the temperature drop,
also referred to as "Delta T" can be determined. The "Delta T"
shown is the drop in fluid temperature as it passes through the
target application. Once the secondary flow rate is determined,
the pressure drop for the heat exchanger can be read from the
chart , see Figure 2. This should be added to the pressure drop
for the rest of the system to determine pumping requirements.
The tables on page 4 show heat exchanger performance for a
range of temperature differentials of 10 to 30 degrees. Some
applications may not work well with high differentials.
NOTE: Not all heat exchangers will fit all models of
Promax SL water heaters. Refer to the Application Table to
insure compatibility.
3
FIGURE 2