14
ASTON COMPACT INSTALLATION MANUAL
Typical open loop piping is shown below. Always maintain water
pressure in the heat exchanger by placing water control valves at
the outlet of the unit to prevent mineral precipitation. Use a closed,
bladder-type expansion tank to minimize mineral formation due to
air exposure. Insure proper water flow through the unit by checking
pressure drop across the heat exchanger and comparing it to the
figures in unit capacity data tables in the specification catalog.
1.5-2 gpm of flow per ton of cooling capacity is recommended in
open loop applications. Due to only minor differences in flow rate
from low to high, only one solenoid valve should be used. The valve
should be sized for full flow.
Discharge water from the unit is not contaminated in any manner and
can be disposed of in various ways, depending on local codes, i.e.
recharge well, storm sewer, drain field, adjacent stream or pond, etc.
Most local codes forbid the use of sanitary sewer for disposal. Consult
your local building and zoning departments to assure compliance in
your area.
Open System - Groundwater Application
Flexible
Duct Collar
Vibration
Absorbing Pad
P/T Plugs
Drain
Hot Water Generator
Connections
Low Voltage
to Thermostat
and Valve
Unit Supply
Aux. Heat Supply
Water Out
Water In
Shut Off Valves
Boiler Drains
For HX Flushing
Disconnects
(IfApplicable)
Rubber Bladder
Expansion Tank
Solenoid
Valve
Shut Off Valves
(to isolate solenoid
valve while acid flushing)
Strainer
Flow Control
Valve
(on outlet of
Solenoid Valve)
Compressor
Line Voltage
Open Loop Ground Water Systems
System Cleaning and Flushing cont.
adjust the make-up water valve to hold the same positive pressure
both before and after opening the drain valves. Flushing should
continue for at least two hours, or longer if required, until drain
water is clean and clear.
The supplemental heater and/or circulator pump, if used, should
be shut off. All drains and vents should be opened to completely
drain the system. Short-circuited supply and return runouts should
now be connected to the unit supply and return connections.
Refill the system with clean water. Test the system water for acidity
and treat as required to leave the water slightly alkaline (pH 7.5 to
8.5). The specified percentage of antifreeze may also be added
at this time. Use commercial grade antifreeze designed for HVAC
systems only. Environol™ brand antifreeze is recommended.
Once the system has been filled with clean water and antifreeze
(if used), precautions should be taken to protect the system
from dirty water conditions. Dirty water will result in system-wide
degradation of performance, and solids may clog valves, strainers,
flow regulators, etc. Additionally, the heat exchanger may become
clogged which reduces compressor service life and can cause
premature unit failure.
In boiler/tower application, set the loop control panel set points
to desired temperatures. Supply power to all motors and start the
circulating pumps. After full flow has been established through all
components including the heat rejector (regardless of season), air
vented and loop temperatures stabilized, each of the units will be
ready for check, test and start up and for air and water balancing.
Ground Source Loop System Checkout
Once piping is completed between the unit pumping system and
ground loop, final purging and charging of the loop is needed. A
high pressure pump is needed to achieve adequate flow velocity
in the loop to purge air and dirt particles from the loop itself.
Antifreeze solution is used in most areas to prevent freezing. Flush
the system adequately to remove as much air as possible; then
pressurize the loop to a static pressure of 40-50 PSI (summer)
or 50-75 PSI (winter). This is normally adequate for good system
operation. Loop static pressure may decrease soon after initial
installation, due to pipe expansion and loop temperature change.
Running the unit for at least 30 minutes after the system has been
completely purged of air will allow for the “break-in” period. It may
be necessary to adjust static loop pressure (by adding water) after
the unit has run for the first time. Loop static pressure will also
fluctuate with the seasons. Pressures will be higher in the winter
months than during the cooling season. This fluctuation is normal
and should be considered when charging the system initially.
Ensure the pump provides adequate flow through the unit by
checking pressure drop across the heat exchanger.
Usually 2.25-3.0 gpm of flow per ton of cooling capacity is
recommended in earth loop applications.
Summary of Contents for Aston Compact Series
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