ECR Argo ARH-1 Installation Manual And Operating Instructions page 10

TERMINAL DESCRIPTIONS Continued
TT- Connect to factory supplied strap-on aquastat at
Hydro-Coil. These terminals must be closed for fan the to
operate in Heating Mode. Install a jumper if no aquastat is
used.
TT- Optional freeze protection when (TT) is connected to
aquastat at Hydro-Coil. When closed, these terminals
start the heating circulator, but the not fan. Using an SPST
aquastat that closes when temperature falls to 40°F with a
5°F differential (MHL 480B), is recommended.
X1X1 - Connect to TT terminal on boiler
X2X2 - Extra End Switch
Y - Cooling Relay (Condenser)
G1 - Heat Fan Center Relay (Low Speed)
G2 - Cool Fan Center Relay (High Speed)
Note: One Speed Fan requires Jumper to be in-
stalled between G1 and G2.
R - 24VAC Hot used to switch all functions.
C - 24VAC Common used to power fan control.
Aquastat
Freeze
Boiler End Switch
Air Handler
10