LAARS Mighty Max HH (Sizes 320M - 1000M) - Installation, Operation and Maintenance Instructions - Manual (Page 9)

Mighty Max Hydronic Boiler Page 9
2G-3. System Pressure Requirements
The Model HH boilers are designed to operate
on closed, pressurized systems. Maintain a minimum
of 12 psi (81.8 kPa) on the system where boiler supply
water temperature is 200°F (93°C) or less. If higher
temperatures are required, the minimum system
pressure should be at least 15 psi (102.2 kPa) above
the water vapor pressure corresponding to the elevated
water temperature.
The Model HH boilers are not suitable for open
systems unless the supply water temperatures are
kept below 180°F (82°C), and a minimum of 5 psi
(34.1 kPa) static head is maintained at the boiler.
2G-4. Hot/Chilled Water Systems
When a boiler is connected to an air
conditioning system where the same water is used for
heating and cooling, you must prevent chilled water
from entering the boiler. When changing such a
system from cooling to heating, allow the chilled
water to circulate through the building, after the
chiller has been turned off, for a period long enough
for the water to warm up to at least 105°F (41°C)
before the water flows into the boiler. It is equally
important to prevent hot water from entering the
chiller. The system shown in Figure 6 is suggested to
make sure the system water is neither too hot nor too
cold when a changeover takes place. When a boiler is
connected to heating coils located in air handling units
(where they may be exposed to refrigerated air
circulation), install a flow control valve or other
automatic means to prevent gravity circulation of
chilled water through the boiler. Chilled water in the
boiler will create condensate on the boiler tubes.
Boilers installed in violation of the foregoing may
void the warranty.
2G-5. Combined Space Heating/Potable
Water Heating Systems
When using the Mighty Max boiler as a source
of heat for a combined space heating/potable water
heating system, be sure to follow the instructions of
the space heating system.
Do not use water piping, fittings, valves, pumps,
and any other components which are not compatible
with potable water.
Do not connect the heater, which will be used to
supply potable water, to any heating system or
components previously used with a nonpotable water
heating system.
Do not add boiler treatment or any chemicals to
the heating system piping, since the piping contains
water for potable use.
Do not use solder containing lead in the potable
water lines.
Some jurisdictions may require a backflow
preventer in the cold water line. In such cases,
pressure relief valve may discharge water due to
expansion. An expansion tank approved for potable
water will eliminate this condition. Follow the
manufacturer's instructions for installation of the
expansion tank.
3-Way Valve No. 1
Change-Over
(Heating and Cooling) 3-Way Valve No. 2
To By-Pass
Both Heater and
Chiller
To
System
From
System By-Pass
To Boiler
and
Chiller
From
Boiler
Valve Motors
2-Pos
3-Wire - 24V
115/24V
Transformer
DPDT Manual or Automatic
Change-Over Switch
DPDT - Set at Change-Over
Temperature
Clock Timer
Auto-Resetting
Set at 15 Minute SPDT
Suggested Wiring Diagram For
Tempering System Water at
Changeover From Heating To Cooling
Figure 6. Boiler-Chiller Installation.
From
Chiller
2H. Piping of System to Boiler
1. Be sure to provide gate valves at the inlet and
outlet to the boiler so it can be readily isolated
for service.
2. The pressure relief valve installed in the tapped
opening provided in the outlet header must be
piped, but not fastened, to a drain or floor sink.
The drain pipe must be the same size as the valve
outlet and must pitch downward from the valve. If
the PRV supplied with the boiler is not factory
installed, install it in the front header consistent
with the ANSI/ASME Boiler and Pressure Vessel
Code, Section IV. Pay special attention to relief
valve settings in installations where the boiler is
located on the ground floor of a tall building, or
where the operating temperature of the boiler is
above 210°F (99°C). In both instances, the static
pressure of the system is elevated and could cause
the relief valve to leak and bring considerable raw
water into the system. Where no special setting of
the relief valve is ordered, the factory will furnish
a 75 psi (511.5 kPa) setting. Never reduce the
relief valve opening. If necessary, install the relief
valve in a Tee immediately past the boiler outlet.