LAARS Mighty Max VW (Sizes 320M - 400M) - Installation, Operation and Maintenance Instructions - Manual (Page 9)

Mighty Max Volume Water Heater Page 9
2.8 Venting and Combustion Air
Information
Provisions for venting and supply of air for
venting and combustion must be done in accordance
with these instructions and applicable requirements of
the latest edition of ANSI Z223.1/NFPA 54. In
Canada, installation must be in accordance with CSA
B149.1, and applicable local codes.
There are a variety of ways to provide venting
and combustion air for the VW heater (see Figure 7).
The Mighty Max VW heater is certified as a true
direct vent unit when installed according to the
instructions for horizontal venting and ducted
combustion air. This can be done even if the runs are
vertical.
2.9 Top-to-Rear Vent Collar Conversion
The Mighty Max VW heater is shipped with the
vent collar on top of the heater. Follow this procedure
to convert it for rear connection (see Figure 8).
1. Remove the adapter plate from the top panel.
2. On the heater jacket, remove the top panel and
ease its lip from under the edge of the bonnet to
gain access to the flue collector.
3. Remove the vent collar/stack from the flue
collector. Do not damage the vent collar/stack
during removal.
4. Remove the blank plate from the rear of the
heater jacket.
5. Remove the blank plate from the rear section of
the flue collector. Be careful not to lose the
insulation attached to the plate.
6. Apply high temperature sealant and install the
blank plate (previously removed from the rear
section of the flue collector) on top of the flue
collector.
7. Install the blank plate (previously removed from
the rear of the boiler jacket) over the stack
opening on the top panel of the boiler.
8. Apply high temperature sealant (see Table 6) to
vent/collar stack and install on the rear of the
flue collector.
9. Slip the adapter plate over the vent collar/stack
and install it onto the rear heater jacket (see
Figure 8).
2.10 Venting
Venting must be in accordance with these
instructions and applicable requirements of the latest
edition of ANSI Z223.1/NFPA 54. In Canada,
installation must be in accordance with the latest
edition of CSA B149.1, and applicable local codes.
2.10.1 Vertical Venting - Category I
The Mighty Max VW heater has a “fan-assisted”
combustion system, so vertical vents must be installed
in accordance with the special code requirements for
Category I - Fan-Assisted Appliances. These
requirements can be found in the latest edition of
ANSI Z223.1/NFPA 54; Chapters 10 & 13 may be
referenced. In Canada, CSA B149.1 should be used
for guidance. These codes permit installation as a
single appliance or in combination with other
Category I appliances. However, there are very
important requirements for minimum and maximum
vent diameter and length. Make sure vertically-vented
installations comply with these codes.
NOTE: If a vent cannot be installed in accordance with
the requirements of these codes, it must be installed
as a horizontal vent, even if it is mainly vertical.
2.10.2 Vertical Venting - Non-Category I
When venting does not meet the code
requirements for Category I - Fan-Assisted Vertical
Vents, it can develop positive pressure. Such venting
must be installed in accordance with this section or
Section 2.10.3.
Table 5. Pump Requirements for Mighty Max VW Heaters.
Soft or Normal Water Hard Water
Pipe Size Flow Headloss Temp, Rise Flow Headloss Temp. Rise
Model in. mm gpm L/m ft. m °F °C gpm L/m ft. m °F °C
0320M 1.5 38 51 193 25.9 8 10.5 6 68 257 46.0 14 7.9 4
2.0 51 51 193 13.9 4 10.5 6 68 257 24.7 8 7.9 4
0400M 1.5 38 51 193 26.0 8 13.1 7 68 257 46.3 14 9.8 5
2.0 51 51 193 14.1 4 13.1 7 68 257 25.0 8 9.8 5
Notes: 1. Pressure dop includes allowance for 30 feet 9.1m of piping and normal fittings. If piping is shorter or of larger
diameter, pump power may be reduced substantially. Contact Laars Representative for assistance.
2. Heaters for soft water application should be equipped with cupronickel heat exchangers.
Soft Water: 0 to 7.5 Grains/gallon
Normal Water: 7.5 to 17 Grains/gallon
Hard Water: More than 17 Grains/gallon
3. The temperature rise across the heater should never exceed 20°F (11°C). Minimum inlet water temperature is
120°F (49°C).
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