IO-123090-GFW-020113
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©2013 AirMark
7) Check the pump to ensure proper operation.
The water inlet of the unit should be hot if the
water temperature in the water heater has
reached the set point. If water is not being
circulated through the coil but the pump is
running, then open the air bleed valve in the
unit and purge any air left in the system.
8) Adjust the water heater thermostat so that the
water temperature entering the hot water coils
is 120 – 180ºF depending on the amount of
heat required by the structure. This is done
with the unit energized and operating long
enough for all temperatures to stabalize.
After all connections are made, start-up and check-
up must be performed before proper evaluation of
the entire system can be made. Make sure that
heat anticipator is properly set as noted on
thermostat instructions.
Load requirements can vary in each residence and
it may be necessary for the installer or homeowner
to make slight adjustments to the heat anticipator
setting for longer or shorter cycles. It is
recommended to change the setting no more than
plus or minus 0.05 amps at a time. Greater
changes can cause the unit to rapid cycle or
remain on excessively. To properly check the unit's
operation, the installer should have an electrical
current measuring device (0-10 amp Amprobe,
Fluke), air pressure measuring device (0-1.0 in
slope gauge), and a temperature-measuring
device (0-200ºF thermometer).
Install the Amprobe to measure blower current, the
slope gauge to measure static air pressure at the
units and the temperature device to measure unit
supply and return air temperature. Before taking
measurements, be sure that all registers, grilles
and dampers are open or are set to their proper
positions. Be sure that clean filters are in place.
Temperature measuring device must be installed
to obtain average temperature at both inlet and
outlet. For outlet, measure temperature of each
main trunk at a location far enough away to avoid
heater radiation and read the average
temperatures. Table 2 below shows the CFM that
should be achieved at various external static
pressures
Fig.9. Schematic of hydronic unit set up
0.10 0.20 0.30 0.40 0.50
Tap 5
900 851 800 742 682
Tap 4
652 630 591 556 530
Tap 3
500 476 452 421 400
Tap 2
900 851 800 742 682
Tap 1
400 381 360 339 312
Tap 5
1150 1087 1030 975 910
Tap 4
1080 1048 1010 960 895
Tap 3
900 862 825 796 745
Tap 2
700 663 632 600 552
Tap 1
500 473 449 421 395
AFW18-24
AFW30-36
SPEED
TAP
MODEL
CFM V. External Static
Pressure
Table 2. CFM delivered at various external statics
GFW18-24
GFW30-36
