Frequently Asked Questions

• Where should I install room temperature sensors?
• When is shielded wire necessary?
• Is it safe to run sensor wires on the exterior of a building?
• One room sensor reads 16 ° F, and another reads 110 ° F. How can I determine whether the room sensor, the control, or the sensor wiring is at fault?
• Can I run sensor wires inside electrical conduits carrying 120 or 24 Vac, or bunch sensor wires with telephone wires?
• Is it safe to run sensor wires through conduits also being used by intercom systems?
• Should I ground the heating control?
• Do cell phones affect sensor readings?
• Is there a way to install a Modem without having to pay for a separate phone line?
• Can the RD1400 series controls be adapted to operate through a Modem?
• Can I mount the outdoor sensor anywhere?
• My heating control doesn't work, what do I do?
• My hot water boiler has turned off after reaching setpoint, but the main circulating pump is still running, what is wrong?

Q. Where should I install room temperature sensors?

A. If possible install room temperature sensors onto walls that are common to closets, usually the hallway closet. The wires can then pass through the wood floors to the basement. Stack sensors of the first and top floors of the same tier in order to minimize the number of apartments that must be accessed. Use #18-4 conductor wire, making the 2-wire junction in the 1st floor apartment leading up towards the upper floor apartment. The 2 extra wires going to the upper floor are useful as spares.
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Q. When is shielded wire necessary?

A. Shielded wire is used when installing the 600W or 600S water temperature sensor. It is not necessary to use shielded wire when installing the 501R room sensor, or the 800E outdoor temperature sensors. For outdoor use, shielded wire can give added protection against cutting or chafing and is therefore more reliable than ordinary thermostat wire.
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Q. Is it safe to run sensor wires on the exterior of a building?

A. Avoid sensor wiring on the exterior of buildings. If you must, run the wire in conduit, or make use of existing cable TV wire chases.
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Q. One room sensor reads 16 ° F, and another reads 110 ° F. How can I determine whether the room sensor, the control, or the sensor wiring is at fault?

A. The technical manuals describe the procedure for determining shorted and open sensor wiring. Testing is done with control power ON, and a digital voltmeter is recommended. Resistance tests are inconclusive unless both an open and short circuit test is performed.
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Q. Can I run sensor wires inside electrical conduits carrying 120 or 24 Vac, or bunch sensor wires with telephone wires?

A. NO, do not run sensor wires within conduits carrying any AC wiring. Older telephones have a solenoid make/break ringer that generates sparks, and can interfere with sensor readings, but modern telephone systems have not been a problem so far.
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Q. Is it safe to run sensor wires through conduits also being used by intercom systems?

A. YES. Intercom signal wiring is either low voltage direct current, or low amplitude audio.
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Q. Should I ground the heating control?

A. You can ground the steel box, which is necessary only if the installation is within 1000 feet of an AM radio station. NEVER ground one side of the 24Vac transformer secondary or any of the sensor wires other than the outdoor sensor. When running shielded wire to the water or room sensors, connect the shields to the sensor (+) lead for each of the sensors at the field wiring board. If you run shielded wire to the outdoor sensor, ground the shield for protection against static energy.
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Q. Do cell phones affect sensor readings?

A. NO, but be aware of Ham Radio Operators and AM radio stations. High frequency radio signals such as cab calls, police and fire radio, and citizen band transmitters will not affect the sensors, unless the antenna is within 10 feet of the sensor. Symptoms of low frequency radio interference are sensor readings that are jumping (decreasing .5 to 3 deg. F.) in synchronization with amplitude or frequency modulated voice signals.
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Q. Is there a way to install a Modem without having to pay for a separate phone line?

A. Yes, several ways. Cheap trick #1; use a fax line, and a timer on the power cord to the fax machine. When you dial in at night, the fax machine will not pick up! Cheap trick #2; use an office voice line, but call in first and have someone turn on the power to the modem. Complex solution; Command Communications (T.M.) sells voice, fax, and modem switches from $80 to $150 which will allow you have a modem, a fax, and an answering machine on the same telephone line. The directions are complicated, and you're required to set up special codes within your communications program enabling the telephone switch to recognize the difference between a fax and a modem incoming call. If the telephone line is voice and answering machine only, no special setup is required.
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Q. Can the RD1400 series controls be adapted to operate through a Modem?

A. No, only the 200 series microprocessor controls can be connected to a modem.
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Q. Can I mount the outdoor sensor anywhere?

A. NO, outdoor sensors must be mounted on a North-facing outside wall, 1 inch beyond the brick surface. If you must use an East-facing wall, make sure the sensor is not in direct sunlight.
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Q. My heating control doesn't work, what do I do?

A. Most panels have a bypass switch on the front panel. Placing the control in bypass will operate a hot water boiler at its high limit temperature, or a steam boiler from the manual bypass control that is supposed to have been connected to the field wiring circuit board terminals labeled “bypass”.  Panels unplug in seconds, and may be sent back to the factory for a rebuilt exchange within 48 hours. Removing the front panel will defeat the external bypass function on some models.  Other models have bypass switches on the backboard itself.  A heating contractor will know how to keep your boiler running while your panel is being exchanged.
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Q. My hot water boiler has turned off after reaching setpoint, but the main circulating pump is still running, what is wrong?

A. Nothing is wrong. The main circulating pump will turn off only when the outdoor temperature setpoint has been achieved. Leaving the main circulating pump on after the boiler turns off allows residual heat within the boiler to be distributed throughout the building, and reduces wear on the pump system.
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