Weil-McLain SlimFit 3 Series Setup guide

is manual must only be used by a qualied heating installer/service technician. Read all instructions, including this manual and
all other information shipped with the boiler, before installing. Perform steps in the order given. Failure to comply could result in
severe personal injury, death or substantial property damage.
Part number 550-100-569/0321
Advanced Manual
Multiple boiler installation & settings + Single boiler advanced settings
®
Series 3
Models 550 and 750 MBH
Commercial Condensing
Gas-red water boilers

Part number 550-100-569/0321
– 2 –
SlimFit®Series 3  — Advanced Manual
Contents
Follow all instructions for installation,
start-up and servicing in the SlimFit
boiler manual.
Use this Advanced Manual for multiple
boiler installation guidelines and control
settings and for single boiler advanced
control settings.
HAZARD DEFINITIONS
e following dened terms are used throughout this manual to
bring attention to the presence of hazards of various risk levels
or to important information concerning the life of the product.
Indicates presence of hazards that will cause
severe personal injury, death or substantial
property damage.
Indicates presence of hazards that can cause
severe personal injury, death or substantial
property damage.
Indicates presence of hazards that will or can
cause minor personal injury or property dam-
age.
Indicates special instructions on installation,
operation or maintenance that are important
but not related to personal injury or property
damage.
IMPORTANT
THE OUTDOOR SENSOR SUPPLIED WITH
THE BOILER IS RECOMMENDED.
If the outdoor sensor is not used, the follow-
ing changes must be made to control settings
during control setup:
TARGET ADJUST (in priority menus) must
be set either to NONE (constant supply tem-
perature) or 0–10VDC (remote target).
WWSD must be set to OFF.
SlimFit Control — Advanced mode . . . . . . . . . 3
Multiple boiler installations . . . . . . . . . . . . . . 6
Fast-Track Setup — Requirements by Boiler . . . . 9
Fast-Track Setup — Steps . . . . . . . . . . . . . . 10
Fast-Track Setup — The WIZARD . . . . . . . . . . 11
Fast-Track Setup — Typical Application A. . . . . . 14
Fast-Track Setup — Typical Application B. . . . . . 16
Fast-Track Setup — Typical Application C. . . . . . 18
Fast-Track Setup — Typical Application D. . . . . . 20
Field wiring (see wiring diagram, ) . . . . . . . . . . . . . 22
Wiring diagram — schematic . . . . . . . . . . . . . 32
Wiring diagram — ladder . . . . . . . . . . . . . . . 34
Zoning with the SlimFit Control . . . . . . . . . . . 36
SlimFit Control — INITIAL SCREENS . . . . . . . . 40
Control operation . . . . . . . . . . . . . . . . . . . 41
Available control settings – Advance Mode . . . . . 43
System Type presets . . . . . . . . . . . . . . . . . 45
CONTRACTOR menus . . . . . . . . . . . . . . . . 46
BOILER SETTINGS menu . . . . . . . . . . . . . . . 47
NETWORK SETTINGS menu . . . . . . . . . . . . . 48
ROTATION AND SEQUENCE . . . . . . . . . . . . . 49
Network Boiler PRIORITY menus. . . . . . . . . . . 52
Single Boiler PRIORITY menus . . . . . . . . . . . . 54
ASSIGN INPUTS menu . . . . . . . . . . . . . . . . 56
AUX PUMP/OUTPUT options . . . . . . . . . . . . . 57
Additional heat demand. . . . . . . . . . . . . . . . 58
MAINTENANCE, DATE AND TIME menus . . . . . . 59

Part number 550-100-569/0321 – 3 –
SlimFit Control — Advanced mode
SlimFit control overview
Basic Boiler Features:
• Easy conguration with WIZARD step-by-step setup including
on-screen help.
• BASIC boiler settings mode for streamlined menu navigation of
essential settings.
• ree customizable input/output pairs—use as a 3-Zone control
or a 3-Priority control.
• Congure outputs to control System Pumps or 120 VAC Auxiliary
equipment.
• System type presets simplify system temperature selection.
• 0-10VDC Input can modulate boiler ring rate or target.
• Integral outdoor reset with warm weather shutdown.
Advanced Boiler Features:
• ADVANCED boiler settings mode unlocks all features and cus-
tomizable parameters.
• Manage multiple types of System Pumps or 120 VAC Auxiliary
accessories.
• Manage staged heating sources using the Additional Heat De-
mand feature.
• BMS integration with standard MODBUS.
Multiple Boiler (Network) Features:
(see next page for explanation of Priorities)
• Create a network of up to 8 boilers using built-in controls.
• Master boiler controls the modulation and sequencing of boilers
on the network to achieve desired system supply temperature.
• Use ALL boiler inputs, not just the rst and last boilers, up to 24
customizable inputs across boiler network (3 per unit, maximum
of 8 boilers on network).
• Two (2) available Network Priorities allow multiple
system types/temperature zones.
• Direct-connected DHW tanks (or other heating zones)
can be piped and wired locally to any boiler in the sys-
tem, not just the rst or the last.
• ree system modulation types—SERIES, PARALLEL,
AND SMART.
• ree (3) Lead boiler rotation modes (plus OFF).
• Limit the ring rate for each Network Priority indepen-
dently when heat demands are mismatched using the
Max System Rate parameter.
• Fire multiple boilers at initial call for heat to start up
quickly for high demand applications using the Mini-
mum Boilers parameter.
• Won’t interrupt a Local heat demand (such as direct-
connected DHW tank) to satisfy Network heat demand
unless all available boilers are at maximum input.
• Simple, 2-wire boiler-to-boiler communication con-
nection.
Additional Heat Demand Features:
• Provides contact and modulating output to activate
other boilers or heating sources (a SlimFit boiler col-
laborating with a heat pump or a dierent boiler, for
examples).
• Modulating output limited to 10VDC; 108µA.
• Congure to operate additional heat demand function-
ality 1st (before SlimFit boiler) or 2nd (aer SlimFit
boiler).
• Select the response time that the primary source is al-
lowed to function before the additional heat demand
activates the secondary source.
• Switch between 1st and 2nd based on a set outdoor
temperature for use in base loading applications.
• Select if the additional heat source is activated based on
the system temperatures being monitored by the SlimFit
boiler (system temperature dependent YES).
SlimFit control operation
• e control responds to signals from:
• Room thermostats
• DHW aquastats (if used)
• Temperature sensors — boiler return, boiler supply,
ue temperature and, when used, system supply and
system return, outdoor temperature. For optimal
performance, it is recommended to install
the system supply and return sensors.
• e control automatically adjusts blower speed (and gas
ow rate) to match boiler output to space heating and/
or DHW heating demand.
• e control provides three inputs and three outputs (for
circulators or auxiliary devices) plus a boiler circulator
output.
• Outdoor reset are recommended to be used in all ap-
plication.
• e outdoor temperature is used for supply tem-
perature reset operation and for the warm weather
shutdown (WWSD) option.
• See “Outdoor reset operation” on page 4 for com-
plete explanation of outdoor reset settings.
• System presets
• e SlimFit control provides presets by System Type
(see Figure24,page45 for complete list).
SlimFit®Series 3  — Advanced Manual
SlimFit control setup
1. Set control parameters using the WIZARD option provided
on initial start-up or manually enter parameters using control
menus explained later in this manual.
2. See
Fast-Track setup instructions beginning on page9 for
example applications and minimum settings required (using
factory defaults).
3. is manual provides set-up information for a single-boiler
advanced settings and for all multiple boiler applications.
Boiler Model, Altitude are critical settings. Failure to set cor-
rectly could result in severe personal injury, death or substantial
property damage.
Temperature settings — You must ensure that the SlimFit
control is set for the proper water temperatures for the system.
Excessive water temperature can cause signicant property dam-
age in some applications.
Multi-temperature systems — If the heating system includes
circuits that require lower temperature water (radiant slab circuits,
for example) as well as higher temperature circuits (DHW, nned
tube baseboard, etc.), it is recommended to protect low-temper-
ature circuits with limit controls that are wired to an SlimFit
control external limit circuit. Failure to provide regulation can
result in substantial property damage.

Part number 550-100-569/0321
– 4 –
SlimFit Control — ADVANCED mode (continued)
SlimFit®Series 3  — Advanced Manual
SlimFit control Priorities & Input/Outputs
• For heating installations with multiple systems, the SlimFit
control uses PRIORITIES to determine the order of opera-
tion of the systems.
• e control’s MAX and MIN time settings determine the
maximum and minimum times a system will be oper-
ated before being turned o to allow another system to
operate.
• A typical example is DHW priority — heat demand from
the DHW system is given preference over space heating
if assigned to Priority1.
• Each PRIORITY has its own set of operating parameters.
• e control prompts the user to select the system type
(nned tube baseboard, DHW, etc.) and is factory pro-
grammed with parameters suited to each of these system
types.
• e user can also choose CUSTOM to create a system
type.
• e SlimFit control provides up to three PRIORITIES for
single boiler applications and up to four priorities for network
boiler applications. e order of operation is:
• Single boilers: PRIORITY 1, PRIORITY 2, PRIORITY 3.
• Network boilers: LOCAL PRIORITY 1, NETWORK
PRIORITY 1, NETWORK PRIORITY 2, LOCAL PRI-
ORITY 2.
• For each boiler in a network, this provides up to two
LOCAL priorities, used for heating systems piped directly
to the boiler, such as DHW tanks.
• NETWORK priorities are used for heating systems con-
nected in the primary heating loop and supplied by the
boiler network.
• Each boiler has three INPUT/OUTPUT pairs (INPUT/
OUTPUT1,2 and3.
• Control setup prompts the user to assign each of these
I/O pairs to a PRIORITY. e SlimFit control then knows
which system (priority) to operate when any input as-
signed to that priority receives a call for heat.
• e SlimFit controls respond to heat calls based on the
order of the assigned priorities and the timings set for
each priority’s operation.
Boiler circulator
• e boiler circulator must be supplied by others.
• e 120 VAC Dry contact for the boiler circulator is located
on the boiler’s Expansion Module. For each of the priorities,
the control can be setup to run the boiler pump or to leave
it o. It is recommended to set Boiler Circulator to OFF for
directly piped DHW systems with its own circulator.
e boiler circulator must be installed and con-
nected. Flow through the boiler must be provided
during all times of operation. Failure to do so can
result in severe personal injury, death or substantial
property damage.
Multiple boiler operation
• e SlimFit boiler has an auto detection feature for multiple
boiler networks. e Master will automatically detect the
presence of the other boilers wired to the network.
• ere will be a 30 second to 1 minute period until the Master
may see the shadow boilers.
• Each shadow boiler must be assigned a network address, from
2 through 8. e address for each boiler must be unique, NOT
selected for any other boiler.
• Aerwards, the Master will build a network based on the
communications shared. If a boiler loses communication, the
Master will automatically re-assign the lost boiler to where
it was before once it is back on the network.
• When network inputs turn on, the Master boiler will enter
the Network Modulation routine.
• Using system sensors, the Master will modulate the entire
network to meet the energy requirements of Network Priority
1 and Network Priority 2 inputs when they are on.
• When a Local Priority input becomes active (switch closes),
modulation for that input is not controlled by the Master,
but instead is le to that local boiler using its own local Heat
Exchanger Inlet and Outlet sensors.
• Each of the three (3) inputs on the Master or any of the
Shadow boilers can be assigned as Network Priority1 or 2
or assigned as Local Priority1 or 2. Network Priority settings
are common across all the boilers. ese Network Priority
settings can only be adjusted from the Master boiler.
Sequence of operation
• Figure22,page42 is a summary of the operating sequence
for the SlimFit control.
• e statuses shown appear in the display as the SlimFit
control cycles the boiler.
• e display will display red (solid or ashing) if a problem
has been detected.
Outdoor reset operation
1. Calculates target temperature for space heating zones based
on outdoor temperature.
2. For an explanation of the target temperatures and associated
outdoor temperatures, see Figure1,page5.
3. e temperature settings discussed below are accessed in
the priority menu for the applicable system. For detailed
explanations of the priority menus, see Figure31,page52.
SUPPLY MAX
1. Set SUPPLY MAX to the required supply water temperature
for the system at design maximum heat loss (typically 180°F
for nned tube baseboard on new installations).
SUPPLY MIN
1. SUPPLY MIN should equal the desired minimum supply
water temperature for the system.
2. is could be set as low as 70°F, which would supply “zero
heat” when outdoor temperature is 70°F, because supply water
temp would equal room temp.
3. See examples in Figure1.

Part number 550-100-569/0321 – 5 –
SlimFit Control — ADVANCED mode (continued)
SlimFit®Series 3  — Advanced Manual
Figure 1 Outdoor reset operation
Figure 2 Remote target operation
OD RESET MAX
1. OD RESET MAX means the outdoor temperature at which the
target temperature reaches its minimum (SUPPLY MIN).
2. In the examples of Figure1, this occurs at 70 °F (the factory
default).
OD RESET MIN
1. OD RESET MIN means the outdoor temperature at which the
target temperature reaches its maximum value (SUPPLY MAX).
2. In the examples of Figure1, this occurs at 0°F outside (the factory
default setting).
3. OD RESET MIN should equal the ODT (outdoor design tem-
perature) for the installation’s location.
Remote target operation (0–10VDC input)
1. is function allows a remote analog input to regulate the supply
temperature for control operation/modulation. is can be done
for any priority, including network and local priorities for multiple
boiler networks.
2. e settings discussed below are accessed in the priority menu
for the applicable system. For detailed explanations of the priority
menus, see Figure31,page52.
3. See Figure2 for an explanation of target temperature vs voltage
when using remote target operation.
4. In the priority menu for the applicable system, select 0-10V for
the TARGET ADJUST setting.
5. In the same priority menu, select the VOLTS FOR MIN and
VOLTS FOR MAX values. VOLTS FOR MIN sets the voltage
value for the desired minimum supply temperature. VOLTS FOR
MAX sets the voltage value for the desired maximum supply
temperature.
Remote modulation operation
(0–10VDC input) — Single boilers only
Using an external multiple boiler controller — Remote
modulation using an external controller only works with
each boiler set up as a SINGLE boiler in the SlimFit
Control setup.
1. Use this option for single boilers only. To use 0–10VDC for remote
modulation, go to Contractor Menu -> Assign Inputs. en change
Input1’s source to 0–10V. e priority that is assigned to Input1
cannot not be used by any other Input.
2. e boiler comes on at 0.9VDC and turns o at 0.8VDC. 2VDC
= 20% input. 10VDC = 100% input. ese voltage settings are
not adjustable.

Part number 550-100-569/0321
– 6 –
SlimFit®Series 3  — Advanced Manual
Placing multiple boilers
1. Locate multiple boilers in boiler room to provide the
clearances shown in:
a. Figure3 (side-to-side), or
b. Figure4 (back-to-back).
2. Provide the indicated clearances around boilers for
access and servicing.
If recommended dimensions are not possible,
provide at least the minimum clearances
given in the SlimFit boiler manual. Also fol-
low applicable local codes.
3. If boilers are oor-mounted, construct a boiler founda-
tion if boiler room oor is uneven or if there is a danger
of ooding. Size the foundation to allow for clearance
and spacing dimensions shown in Figure3 or 4.
4. Provide a minimum 30-inch walkway in front of the
boilers to ensure accessibility.
5. Uncrate, assemble and mount boilers according to
instructions in the SlimFit boiler manual.
6. Provide clearances needed for installation of venting, air
piping, gas piping, expansion tank, primary circulator
and other accessories. Clearances must comply with all
applicable codes.
Motorized air dampers
If the air openings are tted with motorized dampers,
electrically interlock the damper to:
• Prevent the boiler from ring if the damper is not fully
open.
• Shut the boiler down should the damper close during
boiler operation.
To accomplish this interlock, wire an isolated contact
(proving the damper open) in series with the thermostat
input to the boiler. e boiler will not start if this contact is
open, and will shut down should it open during operation.
Manifolded combustion air option
1. Multiple SlimFit boilers can use a common combustion
air manifold.
a. See Figure99, page110 of SlimFit Boiler Manual
for minimum cross sectional area of combined air
ducts.
b. Provide minimum clearance to adjacent vents and
grade/snow line as shown in Figure31 of boiler
manual.
c. Provide minimum free area in duct (adjusted for
louver restriction) of 1 square inch per 2,000
Btuh total boiler input, or divide the total MBH
(1000’s Btuh) by 2.
d. Example: For an MBS system with total input of
3,000,000 Btuh, or 3,000 MBH: Divide 3,000 by
2 = 1500 square inches minimum for a combined
air duct.
e. If combustion air damper is used, wire to boilers to
prevent operation except aer damper has opened
(see Motorized air dampers, above).
Figure 3 Side-to-side mounting of multiple SlimFit boilers
Multiple boiler installations
Figure 4 Side-to-side mounting of multiple SlimFit boilers
Figure 5 Manifolded combustion air option
ONLY air piping can be combined. DO NOT use
combined vent piping. Flue gas leakage and
boiler component damage can occur. Failure to
comply could result in severe personal injury,
death or substantial property damage.

Part number 550-100-569/0321 – 7 –
SlimFit®Series 3  — Advanced Manual
Easy-Fit® piping installation
1. Main header and Easy-Fit® Manifold pipe sizing.
a. Size system piping as required for the ow.
b. Install tees or crosses in the system piping for Easy-Fit®
manifolds as shown in Figure6 orFigure7. Size manifolds
to handle total connected boiler output as shown.
2. Provide connections in main header for Easy-Fit® manifolds
as close as possible to the midpoint of multiple boilers.
a. Use tees for four or less boilers, as in Figure6.
b. Use either tees (Figure6) or crosses (Figure7) for ve
or more boilers.
3. Manifold placement:
a. To alternate spacing for supply and return lines to boilers,
reverse the short-end and long-end of the manifolds as
shown in Figure6 andFigure7.
b. Return manifold must be on the return side of the main
and supply manifold must be on the supply side of the
main.
4. Connect from Easy-Fit® manifold branches to boiler supply
and return connections using copper or steel pipe, sized for
the required ow rate.
5. Install an isolation valve on the supply and return of each
boiler as shown in the piping diagrams in this manual. Some
local codes may require the use of individual water level
controls and limits on each boiler because isolation valves
are installed.
6. Install main system air eliminator and primary circulator in
supply piping as shown in piping diagrams. Place expansion
tank on suction side of system circulator as shown.
7. Install system accessories as shown in drawings.
8. Piping recommendation drawings:
a. Figure6 andFigure7 show details of Easy-Fit® manifolds.
b. Figure8 page8, is a schematic piping drawing showing
the locations of typical boiler piping and system piping,
including limits and other devices oen required by lo-
cal codes.
c. Figure9,page14 and Figure11,page16 are three-
dimensional piping drawings of typical multiple boiler
installation.
d. Figure13,page18 shows recommended piping when an
isolating heat exchanger is needed.
9. If desired, other primary/secondary piping arrangements
can be used.
When using isolation valves on each boiler, some
codes may require additional controls. e control
module uses temperature sensors to provide both
high limit protection and modulating temperature
control, and is UL353 Limit Controls certied to
meet ASME CSD-1 and Section IV requirements.
e control module also provides low water protec-
tion, both with a low water cut-o inside the boiler
jacket and by sensing the temperature of the heat
exchanger. Some codes/jurisdictions may require
additional external controls.
Maximum connected load per manifold:
3-inch manifold — 1400 MBH
4-inch manifold — 2900 MBH
(Do not use manifolds smaller than 3 inch for SF-550 or
SF-750 MBS applications.)
Figure 6 Single-sided EZ-Fit Header connection
Figure 7 Double-sided EZ-Fit Header connection
Multiple boiler installations (continued)

Part number 550-100-569/0321
– 8 –
SlimFit®Series 3  — Advanced Manual
Multiple boiler installations (continued)
Legend — Figure 8
1 Flow/check valve (each boiler)
2 Isolation valves (when used)
3 Caps
4 Easy-Fit® Manifold (supply) — layout and size per page7
5 Easy-Fit® Manifold (return) — layout and size per page7
6 Primary circulator
7 Expansion tank (diaphragm type)
8 System air eliminator
9 System automatic air vent
10 Pressure reducing valve
11 Check valve or backow preventer, as required by applicable
codes.
12 Isolation valve
13 Cold water supply (requires items 10, 11 and 12).
17 Boiler circulator (each boiler)
18 System supply
19 System return
20 Boiler relief valve & discharge piping, installed per SlimFit Boiler Manual.
30 Strap system supply and return sensors to lines as shown, at least 6 pipe
diameters (but no more than 3 feet) from boiler connection tees.
31 Install a union on the boiler supply and return connections as close as
possible to the boiler to allow disconnection for service when required.
32 Pressure/Temperature gauge installed on boiler outlet.
Figure 8 Piping layout — typical piping for multiple SlimFit boilers, using Weil-McLain Easy-Fit manifolds
Use 2” or larger piping for all connections
between boilers and manifolds

Part number 550-100-569/0321 – 9 –
Fast-Track Setup — Requirements by Boiler
Fast-Track Setup
SlimFit control Fast-Track Setup takes advantage of the SlimFit
control WIZARD to provide the shortest possible method to set
up the control.
Perform the Fast-Track Setup steps on page10 to ensure the
minimum adjustments needed for ADVANCED mode control
operation are completed.
e remainder of this manual provides detailed information
about control setup and operation available for ne tuning,
troubleshooting and custom setup applications.
Temperature settings — You must ensure
that the SlimFit control is set for the proper
water temperatures for the system. Exces-
sive water temperature can cause signicant
property damage in some applications.
Multi-temperature systems — If the
heating system includes circuits that require
lower temperature water (radiant slab circuits,
for example) as well as higher temperature
circuits (DHW, nned tube baseboard, etc.),
it is recommended to protect low-temperature
circuits with limit controls that are wired to an
SlimFit control external limit circuit. Failure
to provide regulation can result in substantial
property damage.
Setup for single boilers
For single boilers not operated as part of an SlimFit network,
follow the single-boiler setup procedures in the SlimFit boiler
manual.
Using an external multiple boiler controller —
Remote modulation using an external controller
only works with each boiler set up as a SINGLE
boiler in the SlimFit Control setup. Follow instruc-
tions in this manual to setup the control using
ADVANCED mode.
Multiple boiler networks
Multiple boiler networks are congured with a MASTER boiler
and one or more SHADOW boilers. (See above for applications
using external controller.)
• e
MASTER boiler control regulates the ring of all boilers
when providing heat to the system zones.
• SHADOW boilers respond to heat demand from the master
control except when operating for local (direct-connected)
heat calls.
Priorities
e SlimFit control allows assigning multiple priorities. ese
priorities will be given preference in the order below:
• Multiple boilers: LOCAL PRIORITY1, NETWORK PRIOR-
ITY1, NETWORK PRIORITY2, LOCAL PRIORITY2.
• Single boilers: PRIORITY1, PRIORITY2, PRIORITY3.
DHW circuit in system — For high-demand DHW
circuits, the control setting for MIN BOILERS must
be set using the NETWORK1 or NETWORK2
priority menu aer the WIZARD is completed to
ensure quick response to demand. See page53 for
a description of the MIN BOILERS setting.
Timings
Timing settings regulate boiler sequencing and ensure minimum
and maximum operating times for heating calls on each system.
Timings can be adjusted during the Wizard setup or manually,
as explained elsewhere in this manual.
Also see page49 for additional information on control timings
and rotation and sequencing methods.
NET MIN ON TIME (multiple boilers only)
• is parameter is available during the Wizard or manually
in the NETWORK SETTINGS menu (Figure27,page48).
• When a boiler is being called on by the master boiler to satisfy
a network demand, the boiler will re for at least as long as
the MIN TIME ON NET before it switches to satisfy a Local
Priority if one is active.
• is timing avoids short cycling due to changes in demand.
MIN ON TIME
• is parameter is available during the Wizard or manually
in the PRIORITY SETTINGS menu (Figure32,page54).
• When the boiler is being called on to satisfy a higher priority,
the boiler will re for at least as long as the MIN ON TIME
before it switches to satisfy that priority.
• is timing avoids short cycling due to changes in demand.
NET MAX ON TIME (multiple boilers only)
• is parameter is available during the Wizard or manually
in the NETWORK SETTINGS menu (Figure27,page48).
• When a boiler is being called on by the master boiler to satisfy
a network demand, the boiler will re for no longer than the
MAX TIME ON NET before it switches to satisfy a Local
Priority if one is active.
• is timing avoids a long-duration call from preventing other
demands from being met for too long a duration.
MAX ON TIME
• is parameter is available during the Wizard or manually
in the PRIORITY SETTINGS menu (Figure32,page54).
• When a boiler is being called on by to satisfy a lower priority,
the boiler will re for no longer than the MAX ON TIME
before it switches to satisfy that priority.
• is timing avoids a long-duration call from preventing other
demands from being met for too long a duration.
SlimFit®Series 3  — Advanced Manual

Part number 550-100-569/0321
– 10 –
Fast-Track Setup — Steps
e WIZARD must be used when using the Fast-Track Setup procedure. is is necessary to ensure that all required settings
are made. In addition, all instructions in the SlimFit boiler manual must be followed completely. Failure to comply could result
in severe personal injury, death or substantial property damage.
Step 1
Mechanical
• Install boiler(s) per SlimFit boiler manual and all
applicable codes, including vent/air piping and water
piping.
• See suggested piping in this manual and boiler manual.
Each boiler must be connected with primary/secondary
piping and supplied with a boiler circulator.
• As shown in the suggested piping examples, DHW tanks
can be either piped directly off of individual boilers or as a
separate zone in the heating system.
• See page 6 for additional information on multiple boiler
installation options.
Step 2
Electrical
For details, see FIELD WIRING information beginning
on page 22.
BOILER POWER SUPPLY
• Connect minimum 120 VAC power to boiler as directed
on the boiler wiring diagram (on boiler and on page 32).
INPUTS & OUTPUTS
• Each boiler provides three input/output pairs. Input
circuits are 24 VAC. DO NOT apply voltage. Use dry
contacts only. Outputs are 120 VAC, 2.2-amps max (use
relays if loads exceed 2.2 amps or if outputs must be 24
VAC or must be isolated contacts).
• The input/outputs can be used with zone thermostats and
zone circulators or zone valves (requires isolation relays
unless valves are 120 VAC), providing up to three zones
per boiler on a multiple system.
• Each boiler also provides an unpowered output for its
boiler circulator. Use a external relay if circulator requires
more than 10.0 amps at 120 VAC.
• If a system pump is to be operated by the SlimFit
controls, connect the pump to any of the available
outputs. The system pump can be activated by a
remote contact or can be automatically activated on
heat demand. Set up for pump operation is done in the
ACTIVATE OUTPUT screen of the WIZARD.
SENSORS
• Connect an outdoor sensor, system supply sensor and
system return sensor to at least one of the boilers in a
multiple boiler system..
• Preferably, connect outdoor, system supply and system
return sensors to more than one boiler to provide
redundancy. If one of the sensors fails, the master boiler
SlimFit control automatically looks for an available sensor.
MULTIPLE BOILER COMM CABLES
• For multiple boilers, connect boiler-to-boiler communication
cables as directed on page 31.
ADDITIONAL INFORMATION
• page 31.
• For external limit connections, see page 27.
• For 0–10VDC inputs, see page 29.
ZONING METHODS
• See wiring and control setup information for typical zoning
applications beginning on page 36.
• See example systems beginning on page 14.
Step 3
POWER ON
Follow all instructions in the SlimFit boiler
manual, including all pre-start-up inspec-
tions and nal checks.
• Turn OFF the manual gas cock at the boiler to prevent

• Turn the boiler ON/OFF switch to ON.
• Follow the prompts on the screen to reach the BOILER
SETTINGS initial start-up screen.
• See Figure 20, page 40 for navigation information. Note
that the screen sequence changes after initial setup, as
shown.
Step 4
WIZARD
• Select the START WIZARD option from the
initial screen BOILER SETTINGS menu (see
Figure 20, page 40).
• Use on-screen help as needed. For additional
information, see details in this manual.
• DO NOT select SKIP WIZARD unless the control

SINGLE BOILERS — Set up the con-
trol following instructions in the SlimFit
boiler manual. If ADVANCED settings
are required, change to ADVANCED
mode from the CONTRACTOR menu.
See ADVANCED mode setup information
elsewhere in this manual.
Step 5
Finish setup
• Some additional control settings may need to be
changed, depending on the application.
• See explanation of SlimFit control operation and settings,
beginning on page 41.
• For high-demand loads requiring fast
response, such as network DHW, access the
NETWORK PRIORITY screen for the assigned priority
(see Figure 31, page 52). Change the MIN BOILERS to
the number of boilers needed for peak load.
Step 6
Start-up
• Apply the SlimFit boiler manual instructions to verify the
installation and to start up the boiler, using combustion
test instruments as directed.
SlimFit®Series 3  — Advanced Manual

Part number 550-100-569/0321 – 11 –
Fast-Track Setup — The WIZARD
BO I LER SETT I NGS
H I G H A L T I T U D E : NO
WWSD TEMP: ###ºF
START WI ZARD
SK I P WI Z ARD
FOR DE T A I LS ON ANY
SELECTED L I NE , PRESS
THE BUTTON .
HELP
SELECT ED I T
• is screen appears on initial start-up.
• Perform the
WIZARD steps for every boiler.
• HIGH ALTITUDE are critical parameters. ey
must be entered correctly for each boiler before
proceeding.
• Enter the
WWSD temperature — is sets the
outside temperature below which space heat-
ing systems will be disabled. WWSD must also
be selected during system setup to enable it.
• Select
START WIZARD.
• DO NOT select SKIP WIZARD. Selecting
SKIP WIZARD will take the screen to the
USER MENU. All setup would then have to
be done manually.
• NOTICE — Once SKIP WIZARD has been
selected, the WIZARD will no longer be avail-
able unless the control is set to FACTORY
DEFAULT and control start-up is begun again.
SL IMF I T WI ZARD
## OF ##
WH A T I S T H E U S E O F
INPUT/OUTPUT-#?
HEAT / DHW DEMAND
AUX / PUMP OUTPUT
NOT USED
NO T E :
120V OUTPUTS HAVE A
2.2AMP LIMIT. IF MORE
CURRENT I S REQU I RED ,
USE AN EXTERNAL
CONT AC T .
BACK SELECT NEXT
• Each boiler provides three input/output pairs.
Each pair can be setup to function as a call for
heat with output or to perform an auxiliary
function, such as operating a system pump.
• Aer the WIZARD screens are completed for
INPUT 1, the WIZARD starts over withIN-
PUT/OUTPUT 2, then toINPUT/OUTPUT 3
aer 2is completed.
• Select
HEAT/DHW DEMAND if the input/out-
put is connected to a heating or DHW zone or
system. e input could be a zone thermostat
or end switch. e output could be 120 VAC to
a circulator (2.2amps or less) or isolation relay.
• Select
AUX PUMP/ OUTPUT if the input is
to be used for a system pump, combustion air
damper interlock, etc.
• To operate a system pump, setup the input
as AUX PUMP/OUTPUT. Connect the corre-
sponding output to the system pump or pump
relay (if pump load exceeds 2.2amps). When
the ACTIVATE OUTPUT # screen appears, se-
lect ANY INPUT BY ITS PRIORITY SETTINGS
as the operating mode.
• Select
NOT USED if the input/output is not
needed.
SL IMF I T WI ZARD
## OF ##
WH A T P R I OR I T Y I S
INPUT/OUTPUT-#?
PR I OR I TY 1 - LOCAL 1
PR I OR I TY 2 - NE TWORK 1
PR I OR I TY 3 - NETWORK 2
PR I OR I TY 4 - LOCAL 2
HELP
BACK SELECT NEXT
• For multiple boiler applications, the SlimFit
control provides up to four priorities, as
listed on this screen. Preference is given to
these priorities in the order shown (Priority1
through4).
• Select which priority will be operated by this
input/output.
• All boilers can operate on demand from Net-
work priorities.
• NETWORK PRIORITIES
– Any input on any boiler can be assigned to a
network priority (NETWORK PRIORITY1
or NETWORK PRIORITY2).
– e WIZARD will only allow setting up a
Network Priority on the Master boiler. It
will skip setting up a Network Priority on
all shadow boilers.
– All boilers on the network will re to meet net-
work demands
• LOCAL PRIORITIES
– Any boiler can use its input/outputs to
operate up to two local priorities (LOCAL
PRIORITY 1 and LOCAL PRIORITY 2).
is applies only for heating loops directly
piped to the boiler.
– Local demands are only satisfied by the
boiler to which the input is wired. Local
heating loops must be directly piped to
the boiler.
SL IMF I T WI ZARD
## OF ##
WH A T S Y S T EM T Y P E I S
PIPED TO OUTPUT-#?
FAN CO I L
F I NNED TUBE BASEBOARD
CAST I RON BASEBOARD
CAST IRON RADIATOR
RAD I AN T - S L AB ON GRADE
RADIANT-THIN SLAB
RAD I ANT - BELOW F LOOR
RAD I ANT - ABOVE F LOOR
DHW
CUSTOM-########
HELP
BACK SELECT NEXT
• Use this screen to select the system type for
this priority.
• e control will automatically set operating
parameters to suit the system type chosen.
• To see factory default settings for each system,
see Figure24,page45.
• Operating parameters can be customized in
the next screen, if desired.
• Select
CUSTOM to manually congure the
operating settings for the system.
• NETWORK PRIORITY 1 or 2 — is screen
will not show on a shadow boiler if the input/
output is assigned to a network priority. e
screen will only appear on the Master boiler,
where the priority must be congured.
• e WIZARD is available only on initial setup of the boiler.
It cannot be accessed later. If the WIZARD is accidentally
by-passed, follow navigation sequences shown on page46
and page47. Select RESET FACTORY DEFAULTS on the
Boiler Settings menu. Follow screen directions. Boiler setup
must then be started over from the beginning.
• The
WIZARD leads
through a step-by-step
setup procedure designed
for the application chosen.
• Context-sensitive help
is available to explain
the purpose of key setup
items.
SlimFit®Series 3  — Advanced Manual

Part number 550-100-569/0321
– 12 –
Fast-Track Setup — The WIZARD (continued)
If TARGET ADJUST = ODT
SL IMF I T WI ZARD
## OF ##
SYSTEM TYPE: ########
TARGET MOD SENSOR :
BO I LER OUT
TARGET ADJUST : ODT
SUPP LY MAX : ###°F
SUPPLY MIN : ###°F
OD RESET MAX : # ## ° F
OD RESET MI N : ### °F
BOOST TIME: ###MIN
RUN BO I L ER PUMP ? YES
RUN AUX / PUMP OUT ? YES
MAX ON TIME: ## MIN
HELP
BACK SELECT NEXT
If TARGET ADJUST = 0–10V
SL IMF I T WI ZARD
## OF ##
SYSTEM TYPE: ########
TARGET MOD SENSOR :
BO I LER OUT
TARGET ADJUST : 0-10V
SUPP LY MAX : ###°F
SUPPLY MIN : ###°F
VOLTS FOR MAX: ###°V
VOLTS FOR MIN: ###°V
BOOST TIME: ###MIN
RUN BO I L ER PUMP ? YES
RUN AUX / PUMP OUT ? YES
MAX ON TIME: ## MIN
HELP
BACK SELECT NEXT
If TARGET ADJUST = NONE
SL IMF I T WI ZARD
## OF ##
SYSTEM TYPE: ########
TARGET MOD SENSOR :
BO I LER OUT
TARGET ADJUST : NONE
SUPPLY MAX : ###°F
RUN BO I L ER PUMP ? YES
RUN AUX / PUMP OUT ? YES
MAX ON TIME: ## MIN
HELP
BACK SELECT NEXT
• SYSTEM TYPE – Read only (assigned in
previous step).
• TARGET MOD SENSOR – Read only for
network boilers, adjustable for single boil-
ers – Shows which sensor reading is used for
modulation. Boiler sensor is default for local
priorities. System sensor is default for network
priorities.
• TARGET ADJUST – Select how target tem-
perature is calculated —
NONE (no reset, xed target temperature =
SUPPLY MAX)
ODT (outdoor reset operation; default setting).
Target temperature is calculated from the
outdoor reset curve. SUPPLY MAX is target
temperature when outside temperature equals
OD RESET MAX. SUPPLY MIN is target
temperature when outside temperature equals
OD RESET MIN. At outdoor temperatures in
between, target temperature is scaled propor-
tionally. See Figure1,page5 for details.
0–10V (target temperature based on input
from remote source). SUPPLY MAX is target
temperature at VOLTS FOR MAX value. SUP-
PLY MIN is target temperature at VOLTS FOR
MIN value. For voltage values between max
and min, target temperature is scaled propor-
tionally. See Figure2,page5 for details.
• SUPPLY MAX – Set SUPPLY MAX to the
required supply water temperature for the
system at design maximum heat loss (typi-
cally 180°F for nned tube baseboard on new
installations.)
• SUPPLY MIN – SUPPLY MIN should equal
the desired minimum supply water tempera-
ture for the system. is line will not show if
Target Adjust is selected as NONE.
• OD RESET MAX – means the outdoor
temperature at which the target temperature
reaches its minimum (SUPPLY MIN). (Does
not appear if 0–10V is selected for Target
Adjust.)
• OD RESET MIN – means the outdoor tem-
perature at which the target temperature
reaches its maximum value (SUPPLY MAX).
(Does not appear if 0–10V is selected for
Target Adjust.)
• VOLTS FOR MAX – Appears if 0–10V is
selected for Target Adjust. Set the voltage at
which SUPPLY MAX temperature is required.
• VOLTS FOR MIN – Appears if 0–10V is se-
lected for TARGET ADJUST. Set the voltage at
which SUPPLY MIN temperature is required.
For voltages between Min and Max, the target
temperature will be adjusted on a linear curve.
• BOOST TIME – Every time the call for heat
surpasses this duration of time the target temp
will boost up 10F. It will cap o at Supply Max.
• RUN BOILER PUMP – Selects whether the
Boiler Pump is turned on while running on
this call for heat. is setting is YES for net-
work priorities and is not adjustable.
• RUN AUX PUMP/ OUT – Selects whether
Inputs/Outputs in the system congured as
AUX PUMP/OUTPUT are turned on while
running on this call for heat.
• MAX ON TIME / MIN ON TIME – Maximum
or minimum time the network will run on this
priority if it is being asked to run on another
network priority. MAX shows for Network
Priority1, MIN shows for Network Priority2.
is line ONLY shows on the Master boiler
Wizard. It does not appear on Shadow boilers.
SL IMF I T WI ZARD
## OF ##
ACT I VATE OUTPUT - # :
-ALWAYS ON
-EXTERNAL SWI TCH
- OUT DOOR BE LOW WWSD
-ANY INPUT
-ANY INPUT BY ITS
PRIORITY SETTINGS
- ANY BURNER DEMAND
HELP
BACK SELECT NEXT
• Use this screen to set when a SYSTEM
PUMP/AUX output is activated. For detailed
explanation, see Figure34,page57 and Fig-
ure35,page57.
SlimFit®Series 3  — Advanced Manual

Part number 550-100-569/0321 – 13 –
Fast-Track Setup — The WIZARD (continued)
SL IMF I T WI ZARD
## OF ##
LOCAL
▼
-
▼
NETWORK
SWITCHING TIMES
LP1 MAX ON T IME : ###M
|
▼
▼|
NET M I N ON T I ME : # # #M
NET MAX ON TIME: ###M
|
▼
▼|
LP2 MIN ON TIME: ###M
NEXT STEP HELP
BACK SELECT ED I T
• e timings set on this screen prevent the boiler
from operating too long on one demand if
another demand is present. ey also prevent
short cycling on a demand.
• LP1 and LP2 are times for local priorities.
• MIN NET ON TIME and MAX NET ON TIME
are the maximum and minimum times this
boiler will dedicate to a call from a network
demand.
SL IMF I T WI ZARD
## OF ##
BOI LER SEQUENC I NG
SEQUENCE TYPE :
SMART
BASERATE H I GH : ###%
BASERATE LOW: ###%
LEAD BOI LER ROTATE :
I NCREMENTAL HOURS
ROTATE FREQ : # #DAYS
FORCE LEAD ROT ATE : YES
NEXT STEP
HELP
BACK SELECT NEXT
• Use this screen to set how boilers are sequenced
and how usage is rotated between boilers on
the network.
• For a complete explanation of sequencing and
rotation, see page49 and page50.
• Sequencing means the way in which boiler
ring rate is controlled as boilers are turned on
and o by the master boiler.
– ree SEQUENCE TYPES are available: SE-
RIES sequencing allows each boiler to reach
full input before bringing on the next boiler
in sequence. PARALLEL sequencing uses a
limiter, called BASERATE HIGH, to limit the
ring rate before adding additional boilers.
SMART sequencing (factory default setting)
uses a low ring rate setting, called BASER-
ATE LOW, to keep boilers at a low ring rate,
bringing on additional boilers at reduced rate
until all boilers are on if necessary. Boilers
are then allowed to modulate together as
high as necessary to meet demand.
• Rotation means how and how oen the boiler
ring order is changed.
– LEAD BOILER ROTATE options are based
on how long a boiler has operated. Select ei-
ther OFF, BY BOILER ID, TOTAL HOURS
or INCREMENTAL HOURS. See detailed
explanation of options on page49.
– Use the ROTATE FREQ setting to control
how oen the rotation sequence is changed.
– FORCE LEAD ROTATE – If set to YES,
then when the frequency timer expires and
the new order is calculated, this forces the
new boiler order to take eect while a heat
demand is currently active.
SL IMF I T WI ZARD
## OF ##
SET DATE & T IME
TIME: HH:MM AM
DATE : MM / DD / YY
BACK SELECT NEXT
• is screen appears ONLY on the master boiler,
not on shadow boilers.
• Set the time and date to ensure that control logs
accurately record time/date of occurrences.
• Time and date information is provided to the
shadow boilers by the master boiler.
SL I MF I T WI ZARD
## OF ##
MAINTENANCE INFO
NAME:################
PHONE:### -###-####
MODEL: ####### ###- ##
CP#:##########
INSTALLED : DD/MM/ YY
LAST DATE : DD/MM/ YY
NEX T DA T E : DD / MM / YY
INTERVAL SET: 12MONTHS
WI ZARD COMPLETE
HELP
BACK SELECT NEXT
• Use this screen to enter relevant data about the
installer and boiler.
• See Figure36,page59 for full explanation of
the inputs on this menu.
SlimFit®Series 3  — Advanced Manual

Part number 550-100-569/0321
– 14 –
SlimFit®Series 3  — Advanced Manual
Fast-Track Setup — Typical Application A
Figure 9 Typical Application A — Piping layout — typical piping for multiple SlimFit boilers, using Weil-McLain
Easy-Fit manifolds (2-boiler system) (adjust boiler connections as required for other boiler models)
Legend — Figure 9
1 Flow/check or spring check valve.
2 Isolation valves (when used).
3 Caps.
4 Easy-Fit® Manifold (supply) — layout and size per page7.
5 Easy-Fit® Manifold (return) — layout and size per page7.
6 System circulator. (not used if system is circulator zoned)
7 Expansion tank (diaphragm type).
8 System air eliminator.
9 System automatic air vent.
12 Boiler drain valves.
13 Cold water supply (per applicable codes).
17 Boiler circulator — circulates water between boiler and
Easy-Fit® Manifolds.
18 System supply.
19 System return.
20 Boiler relief valve and discharge piping, installed per SlimFit boiler manual.
21 Indirect-red storage water heaters (Weil-McLain Aqua Plus Line shown) —
Example is shown connected to one boiler of the system. Setup is shown on the
next page for this conguration and also for the option of a DHW tank installed as
a system zone.
22 DHW boiler water supply, typical.
23 DHW boiler water return, typical.
24 DHW boiler-side circulator and ow/check valve.
25 Strap system supply and return sensors to lines as shown, at least 6 pipe diameters
(but no more than 3 feet) from boiler connection tees. For redundancy, you can
install a supply and return sensor connected to each boiler.
31 Unions.
32 Pressure/Temperature gauge installed on boiler outlet.
Suggested DHW
boiler-side pipe
sizing (for max 0.04
feet head loss per foot of
total equivalent length,
TEL)
Flow rate Size Flow rate Size
1 – 3.9 gpm ¾ 24 – 45 gpm 2
3.9 – 7.1 gpm 1 45 – 75 gpm 2½
7.1 – 16 gpm 1¼ 75 - 140 gpm 3
16 – 24 gpm 1½ 140 – 290 gpm 4
See Figure 10, page 15 for setting

DHW is located in the system as
a zone instead of being directly
connected.
NOTICE:
This method does
not provided
DHW redundancy.
DHW can only
be supplied
when Boiler 2 is
operational.

Part number 550-100-569/0321 – 15 –
SlimFit®Series 3  — Advanced Manual
Fast-Track Setup — Typical Application A (cont.)
Boiler Model, Altitude are critical settings. Failure to set correctly could result in severe personal injury, death or
substantial property damage.
Figure 10 Typical Application A — multiple boiler system — setup requirements (parameters not listed below can be

SETUP FOR Figure 9, page 14 AS SHOWN (DHW directly connected)
Boiler Wiring and Control Settings (See Figure 9, page 14 for items referenced)
Boiler
ID
TT
input
Wired
from:
Input
Assignment
Aux
Option Output Wired to: ***
1
Master
1 Zone 1 Tstat Priority 2 - Network 1 N/A 1 Zone 1 Circ/Valve
2 Zone 2 Tstat Priority 2 - Network 1 N/A 2 Zone 2 Circ/Valve
3 No Wire Aux Pump/Output * Any TT Input By It's Priority Settings 3 System Circ
Relay (Item 6) *
2
Shadow
1 DHW Tstat Priority 1 - Local 1 N/A 1 DHW Circ. (Item 24)
2 Zone 3 Tstat Priority 2 - Network 1 N/A 2 Zone 3 Circ/Valve
3 Zone 4 Tstat Priority 2 - Network 1 N/A 3 Zone 4 Circ/Valve
* System circulator will not be used if system is circulator zoned. Aux Pump/Output would not be required.
Priority Settings
Priority # Setting Value Priority # Setting Value
Priority 1 – Local 1
(Boiler 2 only)
System Type DHW
Priority 2 – Network 1
(Boiler 1 only)
System Type Select heating
system type
Run Blr Pump NO Run Blr Pump YES
Run Aux Output NO Run Aux Output YES
SETUP IF DHW IS LOCATED IN SYSTEM AS A ZONE
Boiler Wiring and Control Settings (See Figure 9, page 14 for items referenced)
Boiler
ID
TT
input
Wired
from:
Input
Assignment
Aux
Option Output Wired to: ***
1
Master
1 Zone 1 Tstat Priority 3 - Network 2 N/A 1 Zone 1 Circ/Valve
2 Zone 2 Tstat Priority 3 - Network 2 N/A 2 Zone 2 Circ/Valve
3 No Wire Aux Pump/Output * Any TT Input By It's Priority Settings 3 System Circ (Item 6) *
2
Shadow
1 DHW Tstat (Item 26) Priority 2 - Network 1 N/A 1 DHW Circ/Valve
2 Zone 3 Tstat Priority 3 - Network 2 N/A 2 Zone 3 Circ/Valve
3 Zone 4 Tstat Priority 3 - Network 2 N/A 3 Zone 4 Circ/Valve
* System circulator will not be used if system is circulator zoned. Aux Pump/Output would not be required.
Priority Settings
Priority # Setting Value Priority # Setting Value
Priority 2 – Network 1
System Type DHW
Priority 3 – Network 2
System Type Select heating
system type
Run Blr Pump YES Run Blr Pump YES
Run Aux Output YES Run Aux Output YES
*** Outputs are 120 VAC maximum 2.2 amps. Use relay for other voltages or higher amperages.

Part number 550-100-569/0321
– 16 –
SlimFit®Series 3  — Advanced Manual
Fast-Track Setup — Typical Application B
Figure 11 Typical Application B — Piping layout — typical piping for multiple SlimFit boilers, with DHW storage
heaters (4-boiler system) (adjust boiler connections as required for other boiler models)
Legend — Figure 11
1 Flow/check or spring check valve.
2 Isolation valves (when used).
3 Caps.
4 Easy-Fit® Manifold (supply) — layout and
size per page7.
5 Easy-Fit® Manifold (return) — layout and
size per page7.
6 System circulator (not used if system is
circulator zoned).
7 Expansion tank (diaphragm type).
8 System air eliminator.
9 System automatic air vent.
12 Boiler drain valve
13 Cold water supply (per applicable codes).
17 Boiler circulator — circulates water be-
tween boiler and Easy-Fit® Manifolds.
18 System supply.
19 System return.
20 Boiler relief valve and discharge piping,
installed per SlimFit boiler manual.
21 Indirect-red storage water heaters (Weil-McLain Aqua Plus Line shown) —
Example is shown with each water heater having its own circulator. Alternate:
reverse-return boiler-side piping using a single circulator.
22 DHW boiler water supply, typical.
23 DHW boiler water return, typical.
24 DHW boiler-side circulators.
25 DHW boiler-side supply Easy-Fit® Manifold.
26 DHW boiler-side return Easy-Fit® Manifold.
27 Flow/check or spring check valves (to prevent induced or gravity ow in heating
system or DHW piping).
28 Check valve.
29 See water heater manual for DHW piping — e boiler-side piping in this ex-
ample uses a separate circulator for each DHW tank.
31 Unions.
32 Drain valves for DHW boiler water piping.
33 Strap system supply and return sensors to lines as shown, at least 6 pipe diameters
(but no more than 3 feet) from boiler connection tees. For redundancy, you can
install multiple sensors, each connected to a dierent boiler.
34 Pressure/Temperature gauge installed on boiler outlet.
is piping is
suggested
only. The layout above can be
controlled with the boiler con-
trol’s multi-boiler function, DHW
priority or by an external control
that provides multiple boiler heat-
ing and DHW priorities. is will
provide domestic priority by
disabling the heating system cir-
culator any time there is a DHW
call for heat. e boiler circula-
tors, item 17, must operate on any
call for heat, whether heating
system or DHW. Oset the DHW
boiler-side supply and return
manifolds as shown so the total
run of pipe and ttings to each of
the water heaters is approxi-
mately equal.
Suggested DHW
boiler-side pipe
sizing (for max 0.04
feet head loss per foot of
total equivalent length,
TEL)
Flow rate Size Flow rate Size
1 – 3.9 gpm ¾ 24 – 45 gpm 2
3.9 – 7.1 gpm 1 45 – 75 gpm 2½
7.1 – 16 gpm 1¼ 75 - 140 gpm 3
16 – 24 gpm 1½ 140 – 290 gpm 4
Blr 1
Blr 2
Blr 3
Blr 4
DHW1
DHW2
DHW3

Part number 550-100-569/0321 – 17 –
SlimFit®Series 3  — Advanced Manual
Fast-Track Setup — Typical Application B (cont.)
Boiler Model, Altitude are critical settings. Failure to set correctly could result in severe personal injury, death or
substantial property damage.
Figure 12 Typical Application B — multiple boiler system — setup requirements (parameters not listed below can be

Alternate piping: DHW circuit piped elsewhere in system — If the DHW circuit is piped elsewhere in the
system, the above settings will work only if the System Pump is activated during DHW calls for heat. To set the control
for this, set PRIORITY2 — NETWORK1 with RUN AUX PUMP/ OUTPUT set to YES instead of NO.
Boiler Wiring and Control Settings (See Figure 11, page 16 for items referenced)
Boiler
ID
TT
input
Wired
from:
Input
Assignment
Aux
Option Output Wired to: ***
1
Master
1 No Wire Aux Pump/Output ** Any TT Input By It's Priority Settings 1 System Circ (Item 6) **
2 Zone 1 Tstat Priority 3 - Network 2 N/A 2 Zone 1 Circ/Valve
3 Zone 2 Tstat Priority 3 - Network 2 N/A 3 Zone 2 Circ/Valve
2
Shadow
1 Zone 3 Tstat Priority 3 - Network 2 N/A 1 Zone 3 Circ/Valve
2 Zone 4 Tstat Priority 3 - Network 2 N/A 2 Zone 4 Circ/Valve
3 Zone 5 Tstat Priority 3 - Network 2 N/A 3 Zone 5 Circ/Valve
3
Shadow
1 Zone 6 Tstat Priority 3 - Network 2 N/A 1 Zone 6 Circ/Valve
2 Zone 7 Tstat Priority 3 - Network 2 N/A 2 Zone 7 Circ/Valve
3 Zone 8 Tstat Priority 3 - Network 2 N/A 3 Zone 8 Circ/Valve
4
Shadow
1 DHW1 Tstat Priority 2 - Network 1 N/A 1 DHW1 Circ
2 DHW2 Tstat Priority 2 - Network 1 N/A 2 DHW2 Circ
3 DHW3 Tstat Priority 2 - Network 1 N/A 3 DHW3 Circ
** System circulator will not be used if system is circulator zoned. Aux Pump/Output would not be required.
*** Outputs are 120 VAC maximum 2.2 amps. Use relay for other voltages or higher amperages.
Priority Settings
Priority # Setting Value Priority # Setting Value
Priority 2 – Network 1
System Type DHW
Priority 3 – Network 2
System Type Select heating
system type
Run Blr Pump YES Run Blr Pump YES
Run Aux Output NO Run Aux Output YES
Min Blrs * Select as needed for quick
response
* Min Blrs setting is accessible in the Priority menus (see Figure 27, page 48). It is not included in the Wizard setup options.

Part number 550-100-569/0321
– 18 –
SlimFit®Series 3  — Advanced Manual
Fast-Track Setup — Typical Application C
Figure 13 Typical Application C — Piping layout — typical piping for multiple SlimFit boilers, using isolation
exchanger (adjust boiler connections as required for other boiler models)
Legend — Figure 13
1 Flow/check or spring check valve.
2 Isolation valves (when used).
3 Cap.
4 Easy-Fit® Manifold (supply) — lay-
out and size per page7.
5 Easy-Fit® Manifold (return) — lay-
out and size per page7.
6a Heating system circulator
(exchanger tube-side).
6b Heat exchanger shell-side circulator
7 Expansion tanks (diaphragm type).
8 System air eliminator.
9 System automatic air vent.
12 Boiler drain valves.
13 Cold water supply connections (per applicable
codes).
17 Boiler circulator — circulates water between
boiler and Easy-Fit® Manifolds.
18 Heating system supply.
19 Heating system return.
20 Boiler relief valve and discharge piping,
installed per SlimFit boiler manual.
21 Strap system supply and return sensors to
lines as shown, at least 6 pipe diameters (but
no more than 3 feet) from boiler connection
tees. For redundancy, you can install multiple
sensors, each connected to a dierent boiler.
31 Unions.
32 Pressure/Temperature gauge installed on
boiler outlet.
Notes:
1. Contact heat exchanger manufacturer for heat ex-
changer shell-side and tube-side piping and circulator
requirements. Tube-side ow and temperatures must
meet heating system requirements.
2. Contact heat exchanger manufacturer for sizing heat
exchanger.
3. Heat exchanger shell-side circuit requires its own
expansion tank as shown.
4. Heating system circuit requires its own expansion
tank, as shown, plus its own relief valve set to protect
heating system and heat exchanger piping and com-
ponents.
5. When individual isolation valves are used, individual
boiler and level controls may be required.
Heat exchanger type — is illustration shows a shell and
tube exchanger. Other exchanger types may be used if suitable
for the system water conditions.
Use isolation heat
exchanger for:
1. Large volume systems with high
mineral content in water.
2. Systems exposed to untreated
quantities of makeup water.
3. Old systems severely con-
taminated with scale and rust
buildup inside piping and heat
distribution units.
4. Process applications.
5. Commercial service water ap-
plications.
6. High water pressure applica-
tions, requiring pressure relief
setting in heating system more
than 30 PSIG (tall buildings).
See notes below.

Part number 550-100-569/0321 – 19 –
SlimFit®Series 3  — Advanced Manual
Fast-Track Setup — Typical Application C (cont.)
Boiler Model, Altitude are critical settings. Failure to set correctly could result in severe personal injury, death or
substantial property damage.
Boiler Wiring and Control Settings (See Figure 13, page 18 for items referenced)
Boiler
ID
TT
input
Wired
from:
Input
Assignment
Aux
Option Output Wired to: ***
1
Master
1 No Wire Aux Pump/Output ** Any TT Input By It's Priority Settings ** 1 System Circ (Item 6a)
2 No Wire Aux Pump/Output Any TT Input By It's Priority Settings 2 Shell-side Circ (Item 6b)
3 Zone 1 Tstat Priority 2 - Network 1 N/A 3 Zone 1 Circ/Valve
2
Shadow
1 Zone 2 Tstat Priority 2 - Network 1 N/A 1 Zone 2 Circ/Valve
2 Zone 3 Tstat Priority 2 - Network 1 N/A 2 Zone 3 Circ/Valve
3 Zone 4 Tstat Priority 2 - Network 1 N/A 3 Zone 4 Circ/Valve
3
Shadow
1 Zone 5 Tstat Priority 2 - Network 1 N/A 1 Zone 5 Circ/Valve
2 Zone 6 Tstat Priority 2 - Network 1 N/A 2 Zone 6 Circ/Valve
3 Zone 7 Tstat Priority 2 - Network 1 N/A 3 Zone 7 Circ/Valve
4
Shadow
1 Zone 8 Tstat Priority 2 - Network 1 N/A 1 Zone 8 Circ/Valve
2 Zone 9 Tstat Priority 2 - Network 1 N/A 2 Zone 9 Circ/Valve
3 Zone 10 Tstat Priority 2 - Network 1 N/A 3 Zone 10 Circ/Valve
** System circulator will not be used if system is circulator zoned. Aux Pump/Output would not be required.
*** Outputs are 120 VAC maximum 2.2 amps. Use relay for other voltages or higher amperages.
Priority Settings
Priority # Setting Value Priority # Setting Value
Priority 2 – Network 1
System Type
Select CUSTOM and set
temperatures and other as
needed for heat exchanger
Run Blr Pump YES
Run Aux Output YES
Figure 14 Typical Application C — multiple boiler system — setup requirements (parameters not listed below can


Part number 550-100-569/0321
– 20 –
SlimFit®Series 3  — Advanced Manual
Fast-Track Setup — Typical Application D
Figure 15 Typical Application D — Piping layout — typical piping for multiple SlimFit boilers, using isolation
exchanger (adjust boiler connections as required for other boiler models)
Legend — 15
1 Flow/check or spring check valve.
2 Isolation valves (when used).
6 Heating system circulator
(exchanger tube-side).
7 Expansion tanks (diaphragm type).
8 System air eliminator.
9 System automatic air vent.
12 Boiler drain valves.
13 Cold water supply connections (per
applicable codes).
14 Primary/secondary connections
(tees no more than eight (8) pipe
diameters apart.
17 Boiler circulator — Boiler circulators are piped
to pump into the SlimFit boiler for best results
with the higher pressure drop of the boiler.
Boiler circulators on the High Mass boilers are
piped to pump away from the boiler.
18 Heating system supply.
19 Heating system return.
20 Boiler relief valve and discharge piping,
installed per SlimFit boiler manual. All oth-
ers boiler’s relief valves and discharge piping
installed per manufacturer’s instructions.
21 Strap system supply and return sensors to
lines as shown, at least 6 pipe diameters (but
no more than 3 feet) from boiler connection
tees. For redundancy, you can install multiple
sensors, each connected to a dierent boiler.
27 Flow/check or spring check valves (to prevent
induced or gravity ow in heating system or DHW
piping).
28 Check valve.
31 Unions.
32 Pressure/Temperature gauge installed on boiler
outlet.