4fo2egaP2 rev A9091#ITE
DISCLAIMER
Environmental Technology, Inc makes no representations or warranties, either expressed or implied, with respect to the contents of this
publication or the products that it describes, and specifically disclaims any implied warranties of merchantability or fitnessfor any particular
purpose. Environmental Technology, Inc. reserves the right to revise this publication and to make changes and improvements to the
products described in this publication without the obligation of Environmental Technology, Inc. to notify any person or organization of
such revisions, changes or improvements.
Before disposing of the packing material, verify the inclusion of items in the packing list. Immediately notify CUSTOMER
SERVICE of any discrepancy or shipping damage.
Packing List
Quantity Part Number Description
1 19092 Installation and Operation Instructions
1 19088 FWT-3H Electronic Assembly
2 18581 Wall Plate Screw, White
1 19272 Temperature Sensor/Extension Cable
Installation
Mounting
The FWT-3H Electronic Assembly mounts in a single-gang switch box (customer supplied). Choose a mounting location that
is convenient and reasonably close to the temperature sensor. The Temperature Sensor comes with 20 feet (6.1m) of jacketed extension
cable. The cable length can be shortened if the entire 20 feet is not needed for the chosen mounting location. Shortening the cable will
not affect performance of the FWT-3H. Locate the temperature sensor within the heated space as shown in Figure 1. Do not allow the
temperature sensor or extension cable to cross over or come in contact with any heating source such as a hydronic tubing run.
Though it is not required, it is highly recommended that the temperature sensor/extension cable be housed in conduit as shown.
This will make replacing the temperature sensor much easier in the unlikely event it ever needs to be replaced. The entire length of the
extension cable need not be housed in conduit; only the length traveling through the floor substrate and a short vertical section behind an
adjacent wall (generally where the extension cable rises up out of the floor substrate). Use thin wall conduit with a minimum diameter of
½". Be sure the temperature sensor can pass through the conduit unobstructed when the extension cable is fed through. Cap the end of
the conduit in the heated space prior to installation of the floor substrate. This avoids clogging the conduit and wedging the temperature
sensor against the conduit wall. Also make sure that the temperature sensor reaches the cap at the end of the conduit.
Wiring
Figure 2 shows the relay, Temperature Sensor and power source connections to the terminal block on the back of the FWT-3H
Electronic Assembly. A label on the terminal block identifies these connections. The relay is a normally open isolated contact rated at
3 Amps resistive, or 1 Amp inductive. The FWT-3H requires an NEC Class 2, 24 volt AC power source (customer supplied), rated at
5VA or higher to operate. Many hydronic systems use 24 volts AC, which is suitable for powering the FWT-3H. If power cannot be
derived from the hydronic system, a separate 24 volt AC Class 2 transformer must be used. If the controlled device (pump contactor, zone
valve, boiler control, etc.) is being supplied from the same power source supplying the FWT-3H, make sure the source has sufficient
VA capacity to supply both loads. When making the relay and power source connections, use #18 AWG stranded wires if the wire lengths
needed are less than 50 feet. For lengths more than 50 feet, but less than 150 feet, use #16 AWG stranded wires. For lengths greater than
150 feet, contact CUSTOMER SERVICE. Connect the temperature sensor extension cable leads into to the terminal block as shown in
Figure 2. Reversing these leads does not interfere with operation of the FWT-3H.
May 2008
