MC Series Gas-Fired Circulating Heater - Heat Transfer Products, Inc

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1. Take the 5/16" flexible clear tube (rated for maximum temperature of 120°F)
provided with the heater and place it over the barbed nipple on the manual air vent
as shown in Fig. 31.
2. Fasten the tie wrap (provided) securely around the tube fastened to the barbed
nipple on the manual air vent to keep the plastic tube from separating from the
barbed nipple while purging the system.
3. Turn the manual air vent to the open position as shown in Fig. 31. Air and water
should drain freely from the system.
4. Close the manual air vent when ONLY water flows freely from the end of the
hose.
5. Follow the guidelines in Section E in this section to purge each individual zone
in the system.
6. Remove any electrical connections to the Thermostat terminals and DHW
sensor terminals of the heater. This will prevent the heater from the firing when the
power is applied.
7. Apply power to the heater, making sure that the thermostat terminals are not
connected. The display will show you the temperature of the water and/or air in the
heat exchanger.
Figure 31
Do not open purge valve if displayed temperature is greater than 90 o F.
8. Press the {S1} and {S3} keys on the display simultaneously and hold for 1 second. The display will begin alternating between SEP
and CH and the heater pump will come on. If you press the {S2} key, the heater pump will shut off, the display will begin alternating
between SEP and DH and the DHW pump will come on. Using the {S1} and {S2} keys in this manner you can toggle between running
each pump in the system as required to help bleed out all entrapped air. Some good indicators that air is removed include the absence
of gurgling noises in the pipes and the pump operation becomes very quiet. Pressing {S1} and {S2} together at any time will return the
heater control to normal operation.
NOTE: IF THE INSTALLER DOES NOT CANCEL THIS FUNCTION BY PRESSING {S1} AND {S2} TOGETHER, THE PUMPS WILL
RUN FOR A MAXIMUM OF 20 MINUTES AND SHUT OFF AUTOMATICALLY.
9. While the pump is running as described above, open the manual air vent on the front of the heat exchanger as shown in Fig. 31 to
further assist in removing air from the system.
10. When all air is removed and water runs freely from the end of the hose, return air vent to the closed position shown in Fig. 31. Cut
the tie wrap and remove the tube. Please make sure warning tag is left in place. Stop the pump from running by pressing {S1} and {S2}
together.
11. Reconnect the thermostat and DHW sensor wires to the appropriate terminals on the low voltage terminal strip and fire the heater.
12. If heater makes ping sounds SHUT DOWN IMMEDIATELY and repeat the procedure outlined above until all the air is out of the
system. To avoid overheating and damage to the heat exchanger, it is recommended that the heater temperature be brought up slowly
if air purging had been a problem.
E. PURGE AIR FROM WATER SYSTEM
1. Purge air from system:
a. Connect a hose to the purge valve and route hose to an area where water can drain and be seen.
b. Close the heater or system isolation valve between the purge valve and fill connection to the system.
c. Close zone isolation valves.
d. Open quick-fill valve on cold water makeup line.
e. Open purge valve.
f. One zone at a time, open the isolation valves. Allow water to run through the zone, pushing out the air. Run until no
noticeable air flow is present. Close the zone isolation valves and proceed with the next zone. Follow this procedure until all
zones are purged. After all the zones are purged, open the manual air vent on the top of the heat exchanger as illustrated in
Figure 31. Purge out all air that may have accumulated in the header to avoid air entrapment in the system.
LP-171 Rev. 10.2.13