Just Better DM-2 Digital Manifold - Manual (Page 4)

Form 10728-308
Printed in U.S.A.
2010 JB Industries Inc.
– Use for Thermostat controlled supermarket cases and coolers by monitoring the Average temperature. By this method, obtain
the most accurate Thermostat setting.
– Use the High and Low pressure display to accurately set the low pressure cut-in and cut-out values for pressure controlled
cases and coolers.
– Apply the two temperature sensors, with the Manifold toggled to show the T1-T2 Differential temperature, to measure
temperature drop across a cooling coil.
– Use a wet sock over a temperature sensor to measure the Wet Bulb temperature.
SYSTEM APPLICATIONS
0 5 10 15 20 25
20
18
16
14
12
10
8
6
4
Superheat in °F
Time in Minutes
Expansion Valve Superheat
DM-2 Average Superheat
H u s s m a n n R H F A 4 D o o r F F C a s e
1 Ton Low Temp.TXC
-2 F Case Temperature
40% HeaterLoad
E-Mail: [email protected]
Web Site: www.jbind.com
CHECKING TXV SETTING
The objectives of the TXV superheat setting is to prevent
liquid refrigerant floodback to the compressor and to optimize
system operation by the use of a selected setting.
The two temperature method of measuring superheat is
not recommended because it can produce a wrong
superheat measurement, due to the effect of temperature
glide of the blended refrigerants and variations in evaporator
pressure drop.
NEW RESIDENTIAL A/C SYSTEMS
For new installations of residential A/C systems, the pre-
charge will not provide an accurate amount of refrigerant
charge because of the variation in the length of liquid and
suction line connecting to the “A” coil.
RETROFITTING SYSTEMS
Retrofitting systems to a new refrigerant can change the
TXV superheat setting. The superheat setting should be
checked before and after retrofitting to be sure the superheat
is right for the equipment.
SET SUPERHEAT
FOR “HUNTING”
TXV VALVES
In refrigeration and
air conditioning
systems, the
expansion valve often
operates to produce
an evaporator
superheat which
constantly swings up
and down in value,
called “hunting.” The
DM-2 provides the
“Average” superheat
value to use for TXV
valve adjustment.
JB INDUSTRIES INC.
Aurora, Illinois 60505 USA
®
A/C & REFRIGERATION APPLICATIONS
Contact your TXV manufacturer for the exact superheat adjust rate.
AVAILABLE REFRIGERANTS
R12
R22
R134a
R290
R401A
R401B
R402A
R403B
R404A
R406A
R407A
R407B
R413A
R414B
R416A
R417A * New addition
R422B * New addition
R422C * New addition
R422D * New addition
R427A * New addition
R428A * New addition
R438A * New addition o
R402B R502
R507
R508B
R408A
R409A
R410A
R411C
R407C
R422A
REPLACEMENT ITEMS
PART NO. DESCRIPTION
SH-56 Socks (5)
ACCESSORIES
SH-59 6' Temperature Sensor Clamp
SH-60 6' Temperature Sensor
w/ right elbow (made for DM)
Warranty Information:
Unit has 1 year over the counter warranty due to
Manufacturing defects with proof of purchase.
Customer abuse/neglect not related to
Manufacturing quality will void warranty.