7
SPECTRA COMMERCIAL AND RESIDENTIAL INSTALLATION GUIDE
Ground
Source Closed
Loop Systems
Check the pressure gauge at the pump suction and manually 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. WaterFurnace recommends the Environol™ brand antifreeze.
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 applications, set the loop control panel set points to desired tempera-
tures. 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. Use form WFS159 and when performing
commercial check, test and start up. Obtain these forms from your commercial
representative or contact WaterFurnace.
Ground Source Systems
Once piping is completed between the unit, flow center and the ground loop (Figure 7
on page 8), final purging and charging of the loop is needed. A WaterFurnace flush cart (at
least a 1.5 hp 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 40-60 psi. 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 this “break-in” period. It may be
necessary to adjust static 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. Pressurizing the system to 40-60 psi in the
winter may result in a 15-20 psi static pressure in the summer.
After pressurization, be sure to remove the plug in the end of the loop pump motor(s) to
allow trapped air to be discharged and to insure the motor housing has been flooded.
Insure the loop flow center provides adequate flow through the unit by checking pressure
drop across the heat exchanger and comparing it to the figures shown in Table 3 on page
17. Usually 2.5-3 gpm of flow per ton of cooling capacity is recommended in earth loop
applications. See Wiring Schematic on page 14 for loop pump power wiring details.
Note: Some systems may require adding pressure after the first heating/cooling season.
NOTE:
For closed loop systems with antifreeze protection, set SW1 Switch #4
to the "LOOP" position.
