Monthly Archives: March 2008

Installation recommedations for the Temp-Stat Thermostat

The TS and CL series Temp-Stat™ has been designed to take the place of the conventional thermostat during the construction process.  Temp-Stat™ may be located on the wall in the same location as the permanent thermostat.  It can also be installed in the return air plenum and used as a permanent return air thermostat.  If installed in the return air plenum, Temp-Stat™ should be secured to a vibration-free surface.  Additionally, the fan control may need to be jumpered so that the fan will run continuously.  This may require the furnace filter to be changed more frequently.

Setting a Barometric Bypass Damper

General Instructions for Residential and Light Commercial Barometric Bypass Dampers


As the individual zone dampers close, the system static pressure will tend to rise.  In order to maintain constant airflow through the HVAC system, a barometric bypass damper will be required to bypass some of the discharge air back into the return.  These bypass dampers can be used on systems with static pressure ratings up to 0.75” W.C.


The bypass damper should be installed in such a way as to connect the supply air duct to the return air duct.  The damper should be installed in the horizontal position.  Tap into the return air duct at least two feet back from the return air plenum if possible.


With the HVAC unit running, adjust the weight located on the rod so that the bypass damper is fully closed when all zone dampers are in the full open position.  To increase the system static pressure move the weight outward toward the end of the rod.  To decrease the system pressure move the weight inward toward the damper shaft.  To insure that all zone dampers are in the open position while adjusting the bypass damper, disconnect one of the two wires to each of the spring return open damper motors.  Additional weights can be added to bypass damper arm if necessary.

When attaching the weight and arm to a horizontal barometric bypass damper, adjust the damper arm to the 4 o’clock position when air flow is moving left to right.  Adjust the damper arm to the 8 o’clock position when air flow is moving right to left.

Make a call for heating, cooling, of fan in every zone.  Verify that all zone dampers are in the open position. Verify that the barometric bypass damper is in the closed position.  Slowly move the weight upwards on the arm until the damper starts to open slightly.  Then move the weight back down the arm until the damper stays closed. Close one zone and the barometric damper should open.



Learn how to maximize “free” cooling with an economizer

As seen in the RSES Journal = Breaking Down the Basics of the Economizer, by Phil Kimble.

Due to internal heat loads associated with people, equipment and lighting, most large commercial buildings require year-round cooling. One tool that helps alleviate this excess heat gain is an economizer system. Since the only energy an economizer uses is for blower operation, an economizer system in conjunction with a traditional HVAC system can significantly reduce energy consumption by drawing in or
pushing out the outdoor air. This “free” cooling the economizer provides can be utilized during
mild and cold weather periods.

Economizer systems have existed for many years, but older systems require several motors and controls along with extensive mechanical linkage. Thousands of older, installed economizer systems are nonfunctional due to improper installation, setup and/or component failure. However, most systems can be upgraded and made fully functional by applying new and more reliable components, and thereby sig
nificantly save energy.

Two types of economizers are in use today. A ventilation-type system operates only when the outside air can be used for cooling, as determined by the enthalpy control, without mechanical cooling. An integrated-type system allows the economizer to provide all or some of the cooling, along with supplementary compressor operation, and requires a multi-stage cooling thermostat.

Determining when outside air is useable for free cooling
The enthalpy sensor used in an economizer system senses the relative humidity and temperature.
The control point for the enthalpy sensor within the selected control point value. Outside air is usable for free cooling as long as the humidity level and temperature are on the control point curve. The enthalpy sensor senses the

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Miscellaneous Technical Zoning Notes

1) A thermostat controlling an electric furnace must have the fan switch set in the “electric” position so that the fan is energized immediately with a call for heating.

2) A thermostat controlling a gas furnace should have the fan switch set in the “gas” position so that the furnace controls the fan operation.

3) When using a Honeywell IAQ thermostat with Jackson Systems zone control, configure the thermostat in the installer setup menu as ‘0’, not zoned since the thermostat does not communicate with the zone control panel.

4) Never use an FS-38 Low Limit Freeze Stat in an ambient environment where cold temperatures can influence the stat.

5) The nominal discharge air temperature for heating equipment:
a. Gas – 140
b. Oil – 165
c. Electric – 120
d. Heat Pump – 110

6) Ohms’ Law:  E = Voltage, R = Resistance, I = Current

Voltage:  E=R*I
Amps:      I = E/R
Ohms:      R = E/I

7) It requires more energy for a fan to move cold air than warm air.

8) Mechanical thermostats can have bi-metal, mercury or  magnetic reed switches.

9) The heat anticipator on a mechanical thermostat is designed to turn the furnace off below the setpoint to prevent the space from overshooting.

10) Electronic thermostats are designed with selectable cycle rate adjustment to provide the most efficient operation for the specific heating and cooling equipment being used.

11) Transformer are used in AC (Alternating Current) applications and Power Supplies are used in DC (Direct Current) applications.

Upcoming Events For You To Attend

Two upcoming events that you might be interested in attending if you are close to the Indianapolis area:

Wednesday, March 12, 2008, 10:30 AM – 2 PM : Heating and Air Conditioning Alliance of Indiana Spring Product Showcase and Luncheon.  The event will feature John Hall, Business Editor of ACHR News.  The event is held at Primo South (2615 East National Avenue, Indianapolis, IN 46227) from 10:30 AM – 2:00 PM.  The cost is $8 per person (includes product showcase and luncheon).  To register, please call the Heating and Air Conditioning Alliance of Indiana office at 1-866-880-7633.

Wednesday, March 19, 2008, 5-7 PM : FREE TRAINING!   Honeywell IAQ – Putting it All Together.  Learn how the Honeywell VisionPro IAQ works with all the other IAQ products to create a toatl home comfort system.  You will also learn about all the other Honeywell products including air cleaners, humidifiers, dehumidifiers, UV lights, energy recovery ventilators, ventilation, zoning and thermostats. The training is held at the Jackson Systems Training Room (5418 Elmwood Avenue, Indianapolis, IN 46203). Dinner is provided, so please R.S.V.P. to Doug Engel at or call us at 1-888-652-9663.