LAARS HEATING SYSTEMS
Page 4
Size
15°F 8°C
20°F 11°C
25°F 14°C
Flow Rate
Headloss
Flow Rate
Headloss
Flow Rate
Headloss
gpm
l/s
ft
m
gpm
l/s
ft
m
gpm
l/s
ft
m
50
5.3
0.3
0.3
0.1
4.0
0.3
0.2
0.1
3.2
0.2
0.1
0.0
75
8.0
0.5
0.6
0.2
6.0
0.4
0.3
0.1
4.8
0.3
0.2
0.1
100
10.7
0.7
1.3
0.4
8.0
0.5
0.7
0.2
6.4
0.4
0.5
0.2
125
13.3
0.8
2.2
0.7
10.0
0.6
1.3
0.4
8.0
0.5
0.8
0.2
160
17.0
1.1
2.5
0.8
12.8
0.8
1.8
0.5
10.2
0.6
1.2
0.4
225
24.0
1.5
5.0
1.5
18.0
1.1
3.1
0.9
14.4
0.9
1.9
0.6
5.
The field assembly is now complete. The boiler
is ready for water, gas and electrical connections
and venting installation.
6.
Do not modify the automatic vent damper
device. It is very important that no other vents
are closed. Provide at least six inches clearance
between the automatic vent damper and
combustible construction, and be sure to allow
access for servicing the damper.
Caution
Do not force motor operation when operator is
fastened to the damper by moving the damper
blade, turning the shaft or by turning the position
indicator.
Note: In Canada, the vent damper is optional.
1D. Flow Requirements
All high recovery, low volume water boilers
must have adequate flow for efficient operation. Pump
selection is critical to this goal, and pumps should be
selected to provide for system design water
temperature rise. Table 1 details temperature rise and
water flow (GPM) for the Mini-Therm boilers.
Damage from improper flow is not warranted.
Failure to insure proper water flow through the
heat exchanger of the boiler will void the Laars
warranty. Flow can be verified by measuring the
difference in water temperatures between the boiler
inlet and outlet. For example: For a JV-100
installation, the inlet water temperature is 160°F
(71°C), and the outlet temperature is 180°F (82°C).
That means there is a 20° (-7°C) temperature rise
through the boiler. According to Table 1, that would
indicate a flow rate of 8 GPM (0.5L/S). Temperature
rise must be measured with the longest (highest head)
zone calling for heat alone.
Other factors to be considered before selecting a
pump are pipe size, the number of fittings throughout
the system, smoothness of the interior surface of the
pipe, the quantity of water flowing through the pipe,
whether a glycol solution is being used, and the total
length of piping in the system. Table 2 can help in
making that determination.
1E. Boiler Placement
The boiler must be placed to provide clearances
on all sides for maintenance and inspection. There
must also be minimum distances maintained from
combustible surfaces.
At least 15" (381mm) access must be available in
front of the boiler for burner removal. Consult local
codes for clearances to hot water pipes and
accessories.
If the boiler is to be installed in a garage, all
burners and burner ignition devices must have a
minimum 18" (457mm) clearance above the floor.
The Model JV-50 through JV-100 boilers can be
installed in a closet, as long as the minimum
clearances shown in Table 3 are observed. Special
attention should be paid to clearances between the
front of the boiler and the closet door when it is
closed.
Consult the American National Standard Z21.13
for more information concerning closet installations.
In Canada, refer to the latest edition of CAN/CGA-
B149.1 and 2.
IMPORTANT: The boiler shall be installed on
a floor of non-combustible construction with non-
combustible flooring and surface finish and with no
combustible materials against the underside, or on
fire-resistant slabs or arches having no combustible
materials against the underside unless listed for
installation on a combustible floor.
All boilers must be installed on a non-
combustible surface. That means a surface not capable
of being ignited and burning, such as surfaces
Table 1. Temperature Rise °F
°C.
gpm = Water Flow in gallons per minute.
l/s = Water flow in liters per second.
ft = Pressure drop (headloss) through the boilerin feet of water.
m = Pressure drop (headloss) through the boiler in meters of water.
Note: Shaded area is the recommended flow and temperature rise.
