Installation Instructions

MTU Instruction
for STAR Submetering MTUs with Pulse Adapters
Tools Required
• Crimping Pliers for Insulation
Displacement Connectors (IDCs)
• Wire cutters/stripper
• Cleaner (non-residue type) and
rag/paper towel
• Stapler for ¼” wire and cable
(Arrow T-25M)
Introduction
STAR Submetering MTUs with Pulse
Adapters provide accurate, high-
resolution data for point-of-use allocation
billing for a wide variety of HVAC
appliances.
Note: Only on-off devices are suitable for
application of these pulse adapter MTUs.
• Voltage Sensing Pulse
Adapters can be applied to
gas appliances that are
controlled by a standard
24VAC gas valve.
• Temperature Sensing Pulse
Adapters can be applied to
gas water heaters, fireplaces
and other HVAC appliances
that do not have 24 VAC
controls
These units produce an extremely
accurate pulse at a rate of 10 seconds
per pulse (0.1 Hz or 6 pulses per minute)
when the specified input conditions
(voltage or temperature) are met. These
pulses are counted by the MTU which
periodically transmits the accumulated
count to nearby Data Collector Units.
Note: The submetering MTUs discussed
in this instruction are for indoor use (dry
locations) only.
Connecting Voltage Sensing
(Type P) Inputs
Voltage Sensing (Type P) inputs are
provided with a 2-wire connection that
can be wired across (in parallel with) the
24 VAC gas valve solenoid of the furnace
or other HVAC appliance.
Simply connect the RED and BLACK
wires across the gas valve solenoid.
Once connected in this way, a voltage of
between 18 and 30 VAC applied across
the valve solenoid will cause the MTU to
begin pulsing and recording usage.
CAUTION
Do not connect the white wire
of the MTU when connecting
voltage sensing inputs. Cut
the white wire back to the
cable jacket. Connecting the
white wire may damage the
MTU.
Typical Furnace Application
This procedure covers a typical
installation of a voltage/current sensing
pulse adapter on a gas furnace.
Step 1 - Turn the furnace setting to "Pilot"
so that it will not operate during the
installation process.
Step 2 - Mount the MTU on a wall, joist or
other convenient location near the
furnace to be monitored. Run the cable
from the MTU to the gas valve solenoid of
the device. Trim or extend the MTU
cable, as needed. Care must be taken to
protect the cable from damage by hot
surfaces or sharp sheet metal. Use
insulated staples or cable ties as needed.
Note: Be sure to follow all General
Mounting & Wiring Guidelines outlined in
Publication 471-2000.
Page 44