Laarsen Associates PW Manual Do Utilizador

Page 4

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.

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.

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.

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.

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