Crestron electronic 2, 3.5 Low voltage connections, Enable, Outdoor temperature sensor, ModBus

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7 Field wiring

Low voltage connections

1.Route all low voltage wires through the knockouts in the rear of the boiler, as shown in FIG. 7-2.

2.Connect low voltage wiring to low voltage connection board as shown in FIG. 7-3 on page 38 of this manual and the boiler wiring diagram.

Figure 7-2Routing Field Wiring

LOW VOLTAGE

 

WIRING KNOCKOUTS

LINE VOLTAGE

 

WIRING KNOCKOUTS

LOW VOLTAGE

 

J-BOX

 

LINE VOLTAGE

 

J-BOX

 

Enable

 

1.Connect the room thermostat or boiler enable contacts (isolated contact only) to terminals 7 and 8, as shown in FIG. 7-3.

2.If a thermostat is used, install the thermostat on the inside wall away from influences of drafts, hot or cold water pipes, lighting fixtures, television, sunlight, or fireplaces.

3.Thermostat anticipator (if applicable):

a.If connected directly to boiler, set for 0.1 amps.

b.If connected to relays or other devices, set to match total electrical power requirements of connected devices. See device manufacturers’ specifications and thermostat instructions for details.

Outdoor temperature sensor

1.Connect the outdoor temperature sensor (FIG. 7-3) to the Outdoor Sensor terminals on the connection board to enable outdoor reset operation of the Crest.

2.Mount the sensor on an exterior wall, shielded from direct sunlight or flow of heat or cooling from other sources.

3.Route sensor wires through a knockout at the rear of the boiler (see FIG. 7-2).

Variable speed system pump

If a variable speed pump is used in the primary loop, and a 0-10V signal is available from the pump speed control, this signal can be used by the SMART TOUCH control to anticipate changes in the building heat load. By connecting this 0 - 10V signal to the 0 - 10V SYS PUMP IN terminals, the boiler (or cascade) can modulate up and down as the primary flow increases and decreases.

Installation & Operation Manual

ModBus

The RS-485 ModBus cable is connected to the ModBus terminals. Use shielded, 2-wire twisted pair cable. If desired, the shield can be connected to ground by installing a jumper wire between terminals 1 and 3 on connector X5 on the ModBus interface module.

Hot Water Generator (HWG) thermostat

1.Connect the HWG tank thermostat to the Tank Thermostat terminals on the connection board (FIG. 7-3).

Hot Water Generator (HWG) tank sensor

1.By installing a HWG tank sensor, the SMART TOUCH control can perform the tank thermostat function. The SMART TOUCH control automatically detects the presence of this sensor, and generates a HWG call for heat when the tank temperature drops 6°F (3°C) below the tank set point, and finishes the call for heat when the tank temperature reaches the tank set point.

2.A TST20015 sensor MUST be used with any indirect tank. Failure to use the correct sensor will result in the tank temperature being either above or below the set point. Connect the correct sensor to the Tank Sensor terminals (see FIG. 7-3).

Louver relay

If louvers need to operate before the boiler fires, they can be controlled by this output. Connect these terminals to a 24V relay coil, which is wired to operate the louvers (FIG. 7-3).

Louver proving switch

Louvers are used to provide combustion air for the room air option. A louver proving switch should be connected to the appropriate terminals and are verified prior to operation (see FIG. 7-3).

Boiler pump speed output

This 0 - 10V output is available to control the speed of a variable speed boiler pump. The SMART TOUCH control will vary the speed of this pump in order to maintain a minimum T (set by the installer, see the Crest Service Manual) across the heat exchanger, as well as prevent high limit lockouts when the flow in the primary loop is extremely low. Connect this output to the 0 - 10V input on the boiler pump speed control.

NOTICE

A system supply sensor must be installed

for this feature to work.

 

Rate output

This output provides a 0 - 10V signal that is proportional to the firing rate of the boiler. This may be used by a BMS system to monitor the actual rate of the boiler.

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Contents Save this manual for future reference Contents When servicing boiler Please read before proceedingCrest How it works BlowersCrest How it works Models 1.5 2.0 2.5 3.0 Ratings Crest Ahri RatingInstallation must comply with Determine boiler locationBefore locating the boiler, check Provide clearancesProvide air openings to room Flooring and foundationVent and air piping Prevent combustion air contaminationWhen using an existing vent system to install a new boiler Products to avoidAreas likely to have contaminants When removing a boiler from existing common vent system Remove boiler from wood pallet 7Combustion Air from Outside Single Opening Minimum Recommended Combustion AIR Supply to Equipment Room General venting Direct ventingOptional room air Install vent and combustion air piping Air inlet pipe materialsApproved Stainless Steel Vent Manufacturers Make Model Air intake/vent connectionsRemoving from existing vent Common venting Vertical direct venting Vent/air termination verticalDetermine location Prepare roof penetrationsMultiple vent/air terminations 4Alternate Vertical Terminations with Multiple BoilersSidewall direct venting Vent/air termination sidewallPrepare wall penetrations 2Clearance to Doors and WindowsRoom air 4Multiple Vent Terminations must also comply with FigureHydronic piping Circulator sizing Model20F 40F 60F Near boiler piping components System Multiple Boilers Common Header Primary / Secondary Flow For all equipment and detailing required by local codes Hydronic piping Connecting gas supply piping Gas connectionsModel Gas Inlet Size Natural gas Propane GasGAS Piping Size Chart Check inlet gas supplyGas valve replacement Gas PressureField wiring Installation must comply withLine voltage connections Enable Outdoor temperature sensorLouver proving switch Low voltage connectionsAuxiliary switch 1 Alarm contactsWiring of the cascade System supply sensorWiring FieldCondensate disposal Condensate drainFreeze protection when used Start-upCheck/control water chemistry Fill and test water systemCheck for gas leaks Check thermostat circuitsInspect condensate system Inspect/check condensate lines and fittingsFinal checks before starting the boiler Start the boilerIf boiler does not start correctly Check system and boilerFor Your Safety Read Before Operating Set space heating operation Gas Natural Gas Propane ValveVerify HWG circulator mode Set HWG target temperature Configuration of the cascadeSet clock Operating information GeneralProtection features Boiler temperature regulation Outdoor reset operation, if usedCascade Sequence of operation Crest control module Home Screen2Main Menu Screen Maintenance Maintenance and annual startup Service technicianOwner maintenance See the Crest User’s Information Manual for InstructionsMaintenance Flue vent system and air piping Check water systemCheck expansion tank Check boiler relief valveCheck ignition ground wiring Check all boiler wiringCheck control settings Check flame signalCleaning boiler heat exchanger Review with ownerHandling ceramic fiber materials Niosh stated First AidDiagrams Integrated Control2Wiring Diagram
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