tekmar 055 RTU - Manual

Installation
STEP ONE REMOVING THE FRONT COVER
To remove the front cover, grasp the cover by the top and bottom and pull it away from the RTU.
STEP TWO MOUNTING THE RTU
• The RTU should be installed on an interior wall of the desired zone to be controlled. Do not
mount the RTU in a location that may be affected by localized heat sources or cold drafts.
It may be necessary to install a draft barrier and / or insulation behind the enclosure in order
to prevent air from blowing through the wiring hole and affecting the RTU reading.
• For surface mounting, mount the RTU directly to the wall using two #6-1” screws. The
screws are inserted through the mounting holes and must be securely fastened to the wall.
If possible, at least one of the screws should enter a wall stud.
• For mounting on an electrical box, ensure that the electrical box is properly insulated and
protected from drafts. Mount the RTU on the electrical box using the appropriate screws.
STEP THREE WIRING THE RTU
Run 18 AWG or similar wire between the RTU and the Com Sen-RTU terminals on the control.
Insert the wires through the hole provided in the back of the RTU enclosure and connect them
to the
RT-Com terminals on the RTU terminal block. Do not run the wires parallel to telephone
or power lines. If the RTU wires are located in an area with strong sources of electromagnetic
noise, shielded cable or twisted pair should be used or the wires can be run in a grounded
metal conduit.
If installing a remote temperature sensor, run 18 AWG or similar wire between the remote sensor and the RTU. Insert the wires through
the back of the RTU and connect them to the
Com-Ext terminals on the RTU terminal block. Cut the jumper in the RTU in order to disable
the RTU's internal sensor. Run 18 AWG or similar wire between the RTU and the Com Sen-RTU terminals on the control. Insert the
wires through the back of the RTU and connect them to the Com-RT terminals on the RTU terminal block. For best accuracy, the RTU
and the remote sensor should be approximately at the same temperature.
STEP FOUR TESTING THE RTU
A good quality test meter capable of measuring up to 5000 k
Ω
( 1 k
Ω
= 1000
Ω
) is required to measure the sensor resistance. In addition
to this, the actual temperature must be measured with either a good quality digital thermometer or, if a thermometer is not available,
a second sensor can be placed alongside the one to be tested and the readings compared.
First measure the room temperature using the thermometer. The RTU must be disconnected from the control
before it is tested. Turn the RTU dial to 70
°
F (21
°
C). Measure the resistance of the RTU by touching the test
leads on the wires running to the RTU. Reverse the leads and measure the RTU resistance again. It is necessary
to measure the resistance through the RTU in both directions because there will be two different "Ohm" values
read by the meter. The lower “Ohm” reading is the combined resistance of the dial and the sensor, and the higher
“Ohm” reading is the resistance of the sensor alone.
Using the chart on the following page, estimate the room temperature based on the sensor only (highest)
resistance measurement. Compare the sensor temperature measurement with the thermometer reading. If the
sensor temperature is significantly above the thermometer reading, the wiring may be shorted, moisture may be
in the sensor or the sensor may be defective. If the sensor temperature is significantly below the thermometer
reading, there may be a broken wire, a loose connection or a defective sensor. If a defective sensor is suspected,
first measure the sensor resistance directly at the RTU terminals using the above procedure. Ensure that the RTU
is not connected to the control by removing the wires leading to the control from the RTU terminal block.
03/97
- Data Brochure
Room Temperature Unit (RTU) 055
D 055
The tekmar Room Temperature Unit (RTU) 055 consists of a temperature sensor and an adjustable dial
which is used to set the desired indoor temperature. The RTU 055 dial has a temperature range from 50 to
80
°
F (10 to 27
°
C). The RTU is designed to be mounted onto a standard 2'' x 4" electrical box or to be
surface mounted. A 10K temperature sensor (e.g. 071, 072, etc.) can be connected to the RTU 055 and
mounted separately from the RTU in order to provide remote temperature sensing and control. This 10K
RTU does not work with older tekmar controls that require a 2K RTU. If a greater temperature range is
required, the RTU 054 can be used.
80 (27)
70 (21)
60
(16)
50 ° F (10 ° C)
70 (21)
80 (27)
60 (16)
50 ° F (10 ° C)
Ext Ext
Com Com
R RTT
RTU 055 Heating
80
(27)
70
(21)
60
(16)
50 ° F
(10 ° C)
70 (21)
80 (27)
60 (16)
50 ° F (10 ° C)
ExtExt ComCom
RR
TT
80 (27)
60 (16)
70 (21)
Cut for Ext