The
MZA2 panel
is
made of
s
t
urd
y
ABS
plastic and can be mounted
to
any flat surface. It is
recommended
that the
panel
be mounted to a wall
or return plenum and
NOT
on the
furnace
or plenum where it will be in
contact with the hot
temperatures.. The
panelcan be located in an attic
space
or in an
enclosed
cabinet of a rooftop unit, in order for the panel
to be in direct
exposure
to the elements.
The
cover
easily removes
from the
case
by pulling firmly and separating
the cover from the
case exposing
the circuit board.
There are
4
key
-
h
o
le
mounting poi
n
t
s
in each corner of the case. The
case has openings
in
the rear of the
case as
well
as
the side for all
wiring.
Wiring can come
from the back
as
well
as
the
side
in order to
make
a
neat
installation.
OPERATION
The MZA2 is an extension of the MZS4 zone functions. The MZA2
must use the
same thermostat
wiring configuration
as
the
zones
on the
MZS4. The
MZA2 isnot
used as
a
stand alone
panel.
On a call for heatingor cooling, the panel will accept the
first
call from
any
zone,
providing no other
calls
for heating or cooling
exist
in the
system Upon accepting this call the MZA2 will open its zone
damper(s),
if not open
already, close
the
damper(s)
to those
zones
n
o
t
calling, activate the needed HVAC controls for heating or coo
l
i
n
g
,
whichever
is
being called and not accept any
calls
for the opposite
mode
.
Any
calls
for the opposite mode will be locked out until the initial mode
is either
satisfied
or a period of time
has elapsed
that is
sufficient
for the
first mode to
satisfy,
a maximum of 20 minutes. A Patent Pending
sequence
determines the time the unit has been running or needs
to
continue to run in order to adequately provide conditioning for each
mode.
If a particularmode
has already
been calling for 20
m
i
nut
e
s
o
r
longer and an opposite call comes in the MZA2 will immediately drop
the mode, enter the purge mode in order to
dissipate
the conditioned
air into the zones calling before switching over to provide the new
conditioningcallto its
zone
s.
All other
fu
nctio
n
s
are identical to the MZS4 zone operation, see the
MZS4
Installation Instructions
for further
det
ails.
DIP
Switch Settings
The MZA2 is factory set for conventional single heating and cooling
thermostats. The panel only needs to be configured when using heat
pump specific thermostats.
These thermostats
have a single output Y
connection the call the
compressor
for both heating and cooling. The
reversing
valve terminal O or B is usedto determine whether the Y call
is
for Heat or Cool. When
using
either terminal will determine whether
DIP
S
w
i
t
c
h
2 or 3
is
placed
O
N
.
Never
s
h
o
uld
both be
set
to
O
N
.
S
ee
below for other
DIP Switch
settings.
reversing
valve.
These
thermo
stat
s
will
use
the O terminal
for the
reversing
valve and should be wired
ac
cordin
gl
y
using
DIP
Switch
#3.
The B terminal
will then be wired to
the
C
terminal
on
the thermostat terminal
block.
4.
CONTROL
–
This
switchisfor future
use
.
One of the many features of the DIP switches is if at anytime the
equipment
is changed
from
single stage
to heat pump or vice
versa
the
thermostats
do not need to be changed with the equipment change.
Changing
the DIPswitch
settings
isallthat isneeded.
WIRING
TheMZA2
is
very
simple
to wire and
requires
only a minimum number
of connections. The MZA2 terminal
block
s
are
screw-less
and all wires
can easily be pushed into their respective terminal by
de-pressing
the
button for each point and
releasing
once the wire is seated. To remove
the wire, just
press its
button
again
and
remove
the wire.
Zone
Damper
s
– The MZA2 can power any 24VAC damper, either 2
wire or 3
wire. See specific
wiring
inst
ruc
t
ion
s
with the
damper
or inside
panel
cover.
Zone Thermostats
–
The thermostats
wiring will be for
single stage
(Y
-
G-
R
-
W
-
C
)
or Heat
Pump
(
Y
-
G
-
R
-
E
-
C
and O or
B). This
wiring
is
s
h
o
w
n
on
Diagrams 1 for single stage
thermostats
and 2 for heat pump
thermostats.
Transformer
– A 24VAC, 40VA
Transformer
is required to power the
panel. This
tr
a
n
s
f
or
m
e
r
is wiring to the 24VAC1 and 24VAC2
term
i
n
al
s
on the lower right corner of the circuit board.
Before
wiring to the
MZA
panel, check the
phasing
of this transformerwith the transformerthat
po
w
e
r
s
the
M
Z
S
4
panel.
E
n
s
ur
e
that both
transformers
are in p
h
a
s
e
with one another.
See directions
on
page
4.
Zone Adder
Connection
– The MZA panel communicates with the
M
Z
S
4
using
a
modular, six
(6) conductor cord with
RJ11 jacks
on each
end.
A
seven
(7’) foot cable
is
s
u
pp
l
i
e
d
with each MZA
panel.
T
h
i
s
cord
is
connected to the modular plug on the bottom of the panel and
the other end connected to the modular MZA connector on the MZS4
panel.
Up to 3 additional MZA
panels
are connected in the
same
way
in a
daisy chain
from one MZA
panel
to the
ne
xt
..
WIRING DIAGRAM 1 –
Single Stage
T
herm
o
st
at
ON
OFF
1 2 3 4
1.
TEST
–
Placing this
switch to ON
accelerates
all of the timing
sequences
for second stage and changeover, allowing the
technician to check all operational
funct
i
on
s
in a shorter
period of time.
2.
STAT
O TO W –
S
w
i
t
c
h
Is
placed to ON when
using
Heat
Pump
thermostats
that use an O terminal to activate the
reversing valve in COOLING. The O on the thermostat i
s
wired to W on the zone terminal in order to determineif the
call is for heating or
cooling.
All zone thermostats must
operate
andbe wired the
same
way.
3.
STAT B
TO W –
S
w
i
t
c
h
is used
when
using
Heat
P
um
p
thermostats
that use a B terminal to activate the
r
ever
s
i
n
g
valve
in
H
E
A
T
I
N
G
.
The
B
terminal
on the
t
h
e
rm
o
s
t
a
t
is
wired
to W on the zone terminal in order to determineif the call is
for heating or cooling. All zone
thermostats
must operate
and be wired the
same
way. NOT
E:
Some OEMs use
the
B
terminal as
a
transformer Common
and not
as
the
heatin
g
WIRING DIAGRAM 2 – Heat
Pump
Thermostats
