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The pump in the MZ40C is generally not capable of pumping
normal heating zones outside the heating system. Such
applications normally will require additional series pumping or
a primary-secondary layout. The pump WILL supply adequate
flow for proper operation of one of our BS indirect tanks through
our DHW kit.
When the MZ is properly connected to a primary-secondary
pumping layout, the MZ’s pump will provide the necessary
flow. When the MZ is directly connected to a system in which
the pump inside the MZ is used to pump the entire system,
the system must be checked for proper flow.
If the system is a single-zone system or a multi-zone system
balanced with manually set circuit setters, there either will or
will not be sufficient flow to close the flow switch. If the system
is multi-zone with zone valves used to open and close zones
on demand, the system can be checked for proper flow by
running the system one zone at a time with all of the other
zones off.
If any of the zones restrict flow so much that the flow switch
will not close, adjustment to the system will have to be made,
such as wiring the system so that the restricted zone can
only operate when another zone is running or adding a pump
to that zone, increasing the pipe diameter or zone valve
selection for that zone, or installing a differential pressure-
overflow valve.
LEAVING WATER LIMIT-SWITCH FUNCTION
There is a manual reset high temperature limit switch in the
water jacket of the MZ. In systems with low flow or systems
with water-glycol mixes, it is possible for that manual reset
switch to trip before the call for heat has been satisfied. In
order to check for this possibility, the system should be run
with the adjustable limit switch on the MZ’s panel turned full
clockwise. The temperature - control devices in the system
(thermostats, aquastats etc.) should be adjusted to deliver
the highest temperature that this application will require until
those temperature-control devices are satisfied.
NOTE: If the system has been designed to require high
temperature (>176° F.) water at design conditions, care must
be taken to prevent nuisance trips of the MZ’s manual-reset
high-limit switch. The best ways to do that is to provide for
constant circulation in the winter mode, or add more radiation.
In multi-zone applications, each zone should be run
individually to assure that nuisance limit-switch trips will not
occur during the heating season.
If the manual reset switch trips, pull the adjustable-limit switch
knob and adjust the wire stops in the knob so that the
adjustable limit shuts the MZ down before the over-limit switch
opens. If the leaving-water temperature at that setting will
satisfy the structure’s need for heat on a design day, the
problem has been solved.
If the leaving-water temperature will not satisfy the need for
heat at that setting. Changes to the distribution system, piping
arrangement, pumping provision, control system, or the
addition of radiation may be appropriate. Do not install MZ
heating systems in jobs that require more than 176º F. water.
BS INDIRECT
WATER TANK
Models
Nominal Storage
Height
Diameter
All Pipe Connections
Max DHW Pressure
Aquastat Range
Aquastat Differential
Inspection Port Opening
Nominal Exchanger Power (170ºF Av. system Water Temp)
MZ25 Nominal Reheat Time from 50ºF to 140ºF Stored
MZ25 Continuous Output at 110ºF
MZ40 Nominal First Hour Draw at 70ºF Rise
Dry Weight
Gal.
IN.
IN.
MPT
PSI
F
F
IN.
MBH
MIN.
GPM
GAL.
LBS.
BS 25
25
27.5"
23.6"
3/4"
100
68-176ºF
10.8ºF
3.9"
115
10
3.8
250
71
BS 40
40
36.4"
23.6"
3/4"
100
68-176ºF
10.8ºF
3.9"
115
15
3.8
260
86
BS50
50
45.3"
23.6"
3/4"
100
68-176ºF
10.8ºF
3.9"
200
12
6.5
430
121
BS 80
80
63"
23.6"
3/4"
100
68-176ºF
10.8ºF
3.9"
210
17
6.7
465
159
E. DHW cold inlet.
F. DHW hot outlet.
G. Heating system
circuit inlet.
H. Heating system
circuit outlet.
I. Pressure-
temperature relief
A. 316 L austenitic
stainless steel coil.
B. 316 L austenitic
stainless steel tank.
C. Molded, rigid
removable insulation.
D. Removable ABS
plastic casing.
tap and/or DHW
recycling circuit
tap.
J. Inspection opening
and anode access.
K. Thermometer.
L. Aquastat.
Ratings assume cold-water inlet at 50ºF, heating system circuit average temp of 170ºF and heating system output at least
equal to the nominal heat exchanger power shown above. Tank output cannot exceed heating system output.
INSTALLATION AND TECHNICAL - ACCESSORIES
I I I . A C C E S S O R I E S
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