LAARS Mighty Therm IW (Sizes 500-1825) - Installation, Operation and Maintenance Instructions - Manual (Page 4)

LAARS Heating Systems
Page 4
1C. Flow Requirements
For proper operation, all low volume hot water
heaters must have continuous flow through the heat
exchanger when firing. The system pump must be
capable of developing sufficient pressure to overcome
the resistance of the heater plus the entire circulating
system at the designed flow rate.
1D. Water Chemistry
Laars equipment is designed for use in a wide
variety of water conditions. The water velocity
maintained in the heat exchanger tubes is kept high
enough to prevent scaling from hard water and low
enough to avoid corrosion from soft water. Ninety-
five percent of the urban areas in the country have
water that is compatible with this equipment, but in
some areas a water supply will contain a large quantity
of scaling chemicals or the water may be extremely
soft and corrosive. In rare situations the water will
contain both scaling chemicals and corrosive
chemicals such as calcium or sodium chloride. These
conditions may be the result of a nearby well or
pumping station and the particular condition may not
be characteristic of the entire city water system.
If an installer observes damage from these
conditions to any water handling equipment in the
area, a factory representative should be contacted
immediately for assistance in minimizing maintenance
costs. If erosion is present, the pump impeller can be
replaced to reduce water velocity. If scaling conditions
are bad, tube cleaning maintenance schedules can be
established to prevent tube burn-out and cracking.
Neglecting the problem could mean serious damage to
the heater and water system.
Scaling can be recognized as a layer deposited
on the inner walls of the tube which reduces the inner
diameter of the tube. Scale can be any color or texture;
smooth or rough, granular or amorphous. Signs of
erosion are generally pitting, cavitation, ridges and
“islands” on the inner walls of the tubes. Since this
condition results from extremely soft water sources, or
as a result of a water softening program, the internal
copper surfaces will be extremely shiny. Other
chemicals, such as chlorine or chlorides in the water,
will cause dark surfaces of erosion.
In areas where the water supply is extremely
corrosive, it is advisable to order the heater with
cupro-nickel tubes in the exchanger.
Damage From Scaling, Corrosion, or Erosion
is Not Covered by the Warranty.
SECTION 2.
Installation
2A. Heater Placement
The heater must be placed to provide specific
clearances on all sides for maintenance and inspection.
There must also be minimum distances maintained
from combustible surfaces. These clearances also
apply to non-combustible materials because the heater
requires air circulation for proper operation.
Heater should be mounted on a level surface. An
integral combustible flooring base is provided as
standard equipment on outdoor models. Indoor models
can be installed on a combustible floor with a special
base assembly which is available from the factory, or
with a base that complies with local code
requirements. See rating plate for part number of the
base assembly.
Do not install a heater on carpeting.
Under the National Fuel Gas Code, ANSI
Z223.1, it is permissible to place the heater on floors
other than non-combustible when the installation
complies with the American Insurance Code. Figures
2, 3, 4 and 5 show common installation on
combustible flooring.
2B. Installation of Indoor Heaters
1. Locate the water heater to provide adequate
clearance for inspection and service on all sides
(see Table I). We recommend minimums of 24"
from front (for proper access to and service of
controls) and 18" at water connection end. For
alcove installation (see Figure 6).
2. Install the heater on a waterproof floor with an
adequate floor drain and a 6" minimum curb on
all four sides to protect the building if heater
repairs are required. The manufacturer will not
be held liable for any water damage in
connection with this heater.
Table 1. Minimum Boiler Clearances
From Combustible Surfaces.
Clearance Indoor Outdoor
From (inches) (inches)
Top 30 unobstruct
Water Conn. Side 12 24
Opposite Side 6 24
Front Alcove Unobstruct
Rear 8 24
Vent Pipe* 6 —
Hot Water Pipes Per Code Per Code
*1" when using type B Vent (refer to Manufacturer's
Instructions