LAARS Mini-Therm JVS (Sizes 50-225) - Install and Operating Manual - Manual (Page 18)

LAARS Heating Systems Page 18
Figure 11. By-pass Piping.
Balancing Valve
or optional thermostat-
ic union, Laars P/N
2400-030. (Primary/
Secondary only)
To
System
From
System
In
(Return)
Out
(Supply)
Drip
Leg
Left Side View
A full size by-pass must be installed.
Balancing
Valve
5E 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 7 details temperature rise and water flow (GPM)
for the Mini-Therm boilers.
Damage from improper flow is not warranteed.
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) at Normal Input Rate
from the rating plate. That means there is a 20° (11°C)
temperature rise through the boiler. According to
Table 7, 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 8 provides
example pump selection criteria using Type L copper
piping, one zone valve and up to eight elbows for
single zone systems. Consult the factory or a qualified
system designer if you have more fittings or different
size or type of pipe.
*A circulator and/or primary/secondary piping are required. Consult
factory.
1. Chart is based on 30°F (17°C) maximum temperature rise.
2. Calculations are based on Type L copper tubing with one zone
valve and eight elbows.
3. Typical circulating pumps: 1 /
25
HP=Taco 007, B&G LR-20 or
SLC-25, Grundfos UP15-42F, or equivalent. 1 /
12
HP=B&G LR-
12, Grundfos UP26-42F, or equivalent. 1 /
6
HP=B&G series HV,
Grundfos UP43-75, or equivalent.
Table 8. Maximum Suggested Circuit Length in Feet.
1/2" Pipe 3/4" Pipe 1" Pipe 1-1/4" Pipe
Size Pump Pump Pump Pump
H.P. H.P. H.P. H.P.
1/25 1/12 1/25 1/12 1/6 1/25 1/12 1/6 1/25 1/12 1/6
50 50 99 390 680
* * * * * * *
75
*
35 160 300 460 640
* * * * *
100
* *
77 150 260 330 620
* * * *
125
* *
27 80 140 170 360 600
* * *
160
* * *
25 72 57 160 330 190 480
*
225
* * * * * * *
110
*
69 330
5F Chilled Water Systems
If the boiler is installed in conjunction with
refrigeration systems, it shall be installed so that the
chilled medium is piped in parallel with the heating
boiler with appropriate valves to prevent the chilled
medium from entering the heating boiler.
When boiler piping is connected to heating
coils, which are in close proximity to refrigerated air
circulation, there must be flow control valves or other
automatic methods to prevent gravity circulation of the
boiler water during the cooling cycle.
5G Oxygen Permeable Systems
The JV boiler must not be direct connected to a
heating system utilizing oxygen permeable tubing.
Provide a water-to-water heat exchanger between
systems to prevent corrosion of ferrous metals such
as the boiler’s piping wet walls, etc. Air elimination
devices are not sufficient protection, and corrosion
damage is not covered under the limited warranty.
5H Anti-Freeze
Non-toxic HVAC anti-freeze may be added to the
hydronic system provided the concentration does
not exceed 50%, and the anti-freeze contains an anti
foamant and rust inhibitor. Follow the anti-freeze
manufacturer’s recommendations for yearly or
biannual replacement of system anti-freeze. Never use
automotive anti-freeze in a boiler system.