Greenheck DG / DGX with Pilot Ignition (463555 IOM) (Pre-2008) - Manual (Page 45)

45
Maintenance - Fall
Winterizing Chilled Water Coils
During the winter, chilled water coils need to be protected against freezing. Greenheck recommends protecting
the coils by either blowing-out the coils or by flushing the coils.
Blowing-Out Coils
1. Close valves on the supply and return line.
2. Open drain valves and/or drain plug. Remove
vent plug to allow coil to drain faster.
3. After coil is fully drained, connect a blower to
the caps. Do not connect the blower to the air
vent or drain plug.
4. Close the vent plug on the header that the
blower is connected to. Open the drain valve
or cap on the other header.
5. Turn on blower for 30 minutes. Place mirror at
discharge. If the mirror fogs up, repeat
procedure until no fog appears on the mirror.
6. After drying the coil, wait a few minutes then
repeat Step 5.
7. Leave drains open and do not install plugs
until beginning of cooling season.
Flushing Coils
Greenheck recommends the use of inhibited glycol
(such as propylene or ethylene) to flush water coils to
protect against freezing. Additionally, the use of
inhibited glycol provides corrosion protection.
The tables below indicate the percentage of glycol
required to prevent freezing in a coil at a given
outdoor air freeze point. Completely fill coil with
solution. Drain coil. Residual glycol fluid per these
concentrations can be left in the coil without concern
of freezing. Recovered fluid can be used to flush
other coils.
% Ethylene Glycol
By Volume
Freeze Point
(ºF)
0 32º
10 25º
20 16º
30 3º
40 -13º
50 -34º
60 -55º
% Propylene Glycol
By Volume
Freeze Point
(ºF)
0 32º
10 26º
20 19º
30 8º
40 -7º
50 -28º
60 -60º
Maintenance