Monthly Archives: July 2008

Jackson Systems Announces TK-400 Universal Twinning/Paralleling Kit

Jackson Systems, LLC, an Indiana-based, award-winning HVAC manufacturer and wholesaler, announces the TK-400 Universal Twinning/Paralleling Kit. The TK-400 is designed to allow a single thermostat to control two separate HVAC units. The TK-400 can also be expanded to control a total of four HVAC units.

“We saw a need among our clients for a simple product to perform like the TK-400 and were able to quickly develop a solution to this need,” said Tom Jackson, C.E.O. of Jackson Systems. “The HVAC industry now has an easy-to-use product for controlling multiple HVAC units. HVAC contractors will appreciate the simple application with precise control.”

The TK-400 can be used on common or separate ducted systems with single stage (1 Heat / 1 Cool), multi-stage (2 Heat / 2 Cool) and heat pump (3 Heat / 2 Cool) equipment. Only standard 18 gauge thermostat wire is required. Thermostats and HVAC units can be located up to 300 feet from the TK-400 panel. When HVAC units share a common return and supply duct, backdraft dampers should be installed and thermostat fan operation must be set for electric.

Key features of this product include: 
 Easy to install and set-up
 Competitively priced
 Strong Technical Support
 Design assistance available
 All orders shipped the same day
 Free standard shipping
 5 year warranty
 Factory direct to contractors
 Online ordering

This product is available in-stock now and may be purchased online at or by calling toll-free 1-888-652-9663.

Honeywell thermostats and the “L” terminal as a heat pump monitor

Homeowners will sometimes want their thermostat to monitor their heat pump.
Thermostat manufactures typically can use an “L” terminal on their thermostat to receive a 24V signal from the heat pump.  The “L” terminal might be designated “system monitor” or “heat pump fault light”.  Here is a quick explanation of the “L terminal used on Honeywell thermostats.
The VisionPRO TH8320 has an “L” terminal as a 24V input in the heat mode.  Only when moved to the emergency heat mode does the “L” terminal become an output.
The VisionPRO IAQ thermostat uses the “L” terminal as an input all the time.
The FocusPRO family uses “L” as an output only.
Always make sure to read the Installation Manual thoroughly when installing any thermostat.

Triac switching or power stealing thermostats used with the Z-200 series of zone control panels

Contractors sometimes ask if they can use any thermostat with our new Z-200 Green Zone.  Most thermostats will work great with these panels, especially thermostats that use relay switching; however, we need to be aware of power stealing thermostats and some thermostats that use triac switching.  One example of a thermostat that uses triac switching is a Totaline thermostat.  Some triac and power stealing thermostats require at least a 35mA load to close the circuit, while relay switching thermostats do not require any load to close the circuit and bring on the equipment.  In order for some triac thermostats to function properly with our Z-200 boards, we may need to add load resistors.  In fact many triac thermostats come with a large load resistor because they anticipate a potential problem closing the circuit.  You will need to follow the thermostat manufacture’s instruction manual in installing this load resistor. You could add your own load resistor between C and Y1 and another load resistor between C and W1.  These load resistors should be1000 ohms and 2 watts.  Adding these load resistors should allow thermostats that use triac switching and power stealing thermostats to work with the Z-200 series of panels.

Balancing a Zoned System

The article below was written by Rob Falke, president of the National Comfort Institute, and was featured in the Contracting Business e-newsletter. 

Balancing a Zoned System
By Rob Falke

Although the process for balancing a zoned system is similar to that of a constant volume system, balancing a zoned system can present a separate set of challenges and opportunities.

Balancing a constant volume system fixes the airflow to meet design conditions for the warmest days of summer. As the unit cycles on and off in rooms that share a similar load, adequate comfort is achieved. But where the sun travels across the sky under hot summer conditions, some rooms are built with exposures that require “conditional balancing” or zone dampers that alter the airflow or balance in a room to satisfy changing conditions throughout the day.

Balancing a zoned system requires a few more steps.  Lets take a look at the zoned system balancing procedure and investigate the differences. The added work increases the labor 25% to 40% on a typical residential or light commercial project.

The first step is to inspect the system and compare the plan to what actually got built. This sounds really basic, but is critical for balancing a system. Check the usual components:

• Did all the duct runs get installed?
• Are all the end caps there?
• Are the manual dampers open?
• Are the supply registers delivering supply or return air volume?

Then check the added zoning components:

• Is the bypass duct installed?
• Is the control panel wired correctly?
• Were all the dampers installed and connected?
• Does each of the dampers operate freely when called to function?

Also, check the entire building for pressure imbalances that may be caused when dampers open and close. Each zone should have a return air duct that can handle the airflow under the zones highest airflow condition.

Start Balancing

To begin balancing, set all zoning dampers in open position. The better zoning systems have a switch in the control panel that allows the balancer to do this.

• Set each thermostat in cooling mode at 55 degrees with the fan on to open all the zoning dampers 100%.
• Let the system run until the coil is wet.
• Take your initial airflow readings by measuring and recording the airflow at each register and grille.
• Then, using the manual balancing dampers, balance each grille and register to the amount of airflow required under full cooling mode.
Up to this point, the balancing is similar to balancing a constant volume system.
• Add together all the supply register airflows and check for 400 CFM per ton. If airflow is low, measure total external static pressure by measuring pressure before and after the air handler and adding the pressures together.

If needed, measure the pressure drop over the filter and the coil. Increase fan speed as needed. Then adjust the manual balancing dampers so each register gets the required airflow.

The accepted rule is plus or minus 10%.
• Lock down and mark your manual balancing dampers. The system is balanced under constant volume conditions.

Do final testing that includes system temperatures, static pressures, blower motor and draw, and fan RPM and record these numbers on you balancing report.

Zone Balancing

• Close down the largest zone in the system.
• Next traverse the bypass duct to check the volume of bypass air.
• Then by manipulating thermostat controls, open and close each of the zones in the system.
• Test and record the zoned airflows and temperatures through the system under partially closed operating conditions.
• Check for noise caused by excessive velocities.
• As the zones open and close, measure the airflow passing through the bypass duct. Adjust it as necessary to assure quiet system operation and adequate temperatures through the heating and cooling equipment.
• Check for excessive changes in total external static pressures or temperature drop or rise in the system.
• Mark your final damper settings.
• Complete your final equipment testing by measuring and recording full open pressures, temperatures, speed and electrical values, and complete the job as you would a constant air volume system.
• Write an advisory statement to include with your final report describing the operation of the system with the largest zone closed. Include additional test numbers and observations you have made of the system. Make any design change or repair recommendations that may improve the quality of the system, if necessary.
• Instruct the customer in proper use of the controls and help them understand what they can expect from their new system. Present a final bound copy of the balancing report with all the required paperwork, warranty information and service agreements.

Consider zoning as a tool to adapt balancing to the temperature requirements of certain rooms that have varying load conditions. As you design systems, be aware of rooms that may need more than just air balancing to keep them throughout the day and comfortable all year.

Rob Falke is president of the National Comfort Institute ( He can be reached at 800/633-7058, e-mail

To learn more about Jackson Systems, visit

Barometric Bypass Damper

A question that comes up frequently when quoting zone control systems is, why and when do I need a bypass damper?  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 damper can be used to bypass some of the discharge air back to the system.  The bypass damper should be installed in such a way as to connect the supply air duct to the return duct.  Damper adjustment is done by moving the weight up and down the arm.  If only two zones are required, size each zone to handle about 75% of the total CFM.  This method does not require a bypass damper.  If one zone requires substantially more CFM than the other, it is recommended that the larger zone damper be set to bleed about 20% of its air.  If more than two zones are required, install a bypass damper.  It should be set to bypass just enough air to maintain a quiet, draft free system.  Barometric bypass dampers can be used on systems with static pressure ratings up to 0.75”W.C.  Bypass dampers are sized based on the cooling tonnage.

Condensing Unit Damper Size
2.5 tons or less 8” bypass
3 tons 10” bypass
4 tons 12” bypass
5 tons 12” bypass
7.5 tons 14” bypass
10 tons 14” bypass

For systems larger than 10 tons, subtract the CFM of the smallest zone from the total system CFM, then size the bypass damper to handle 100% of this difference at 2,500FPM.

Troubleshooting a Z-600 when the compressor keeps cycling off on low limit

Sometimes we get calls from contractors looking for help and information on a Z-600 control board that is cycling off on low limit.  The following are some ideas to keep in mind if you come across this situation.

1) Verify the chip is version 1.6.
2) Verify the low limit adjuster is set at 48°F.
3) Verify the discharge air temperature using an accurate digital thermometer.
4) Is it possible that we are bypassing more air than is necessary and causing the coil temperature to drop?
   a. If we are bypassing too much air we can adjust the bypass damper to open at a higher static   pressure by moving the weight down the arm.
5) Last case measure.  We can disconnect the DAS and not use it.  Use an FS-38 wired in series between Y1 of the board and Y1 of the equipment and install it on the suction line.

There is usually a 20°F temperature difference between the discharge air temperature and the coil temperature; therefore, a 48°F discharge air temperature will give us approximately a 28°F coil temperature.  We do not want to go below 48°F discharge air temperature.

Coils can freeze when there is not enough air going across the coils or if the air going across the coils is to cold.

Possible reasons the air going across the coils is too cold.
1) We are bypassing too much air.
2) Verify the correct setting of the bypass damper.
3) Adjust the bypass damper to open at a higher static pressure by moving the weight down about 1” after you have it set normally.

Possible reasons there is not enough air going across the coils (400cfm per ton)
1) Dirty filter
2) Undersized return air duct
3) Dirty or plugged coils
4) Fan speed is set to low

Join us at our Summer Cookout

Fire up the Grill Summer is Almost Here!

Join us at our summer bash, cookout style on Friday, July 18th @ Jackson Systems from 11 a.m. – 2 p.m.  5418 Elmwood Avenue, Indianapolis, IN 46203

Meet reps from Honeywell, White-Rodgers, and Braeburn.  Free give-a-ways, games, burgers, hot dogs, drinks and more.  Don’t miss out!

R.S.V.P. to Erica Gardner at, 317.222.7208


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National HVACR Service Managers Forum

Join Jackson Systems at the National HVACR Service Managers Forum October 9 & 10, 2008 at the Doubletree Hotel Houston in Downtown Houston, Texas.

Service managers are key to contracting success.  Get a leg up on your competition at the Service Managers Forum!

The First Annual National HVACR Service Managers Forum is the first national educational program designed exclusively for Service Managers – the people who run a service department and make a big difference in contracting success.

To learn more about Jackson Systems, visit

111 tips to help your business become more profitable

One of our great industry friends, John Hall, has published a new book about the HVAC industry.  As many of you know John is the Business Editor for The Air Conditioning, Heating & Refrigeration News ( His new book is titled Profit Tips 1.1.1. and includes 111 tips to help your business become more profitable. Each tip is endorsed and ‘embellished’ by 111 real-life contractors who have added their names because they believe in them and John thinks you will too.

Here is an excerpt from the book:

TIP #21

     Cheaters never prosper – unless they use cheat sheets. Or should I rephrase that and say – because they use cheat sheets. We all know about cheat sheets. Kids use them in classrooms when taking tests by writing answers down on scraps of paper and hiding them in their shirtsleeve. Or better yet, kids write answers on their wrists or ankles – very clever.
     But not all cheat sheets have to emulate cheating. Some of these little scraps of paper can be called reminder sheets. You have seen them – the yellow sticky notes all over the place with various notes. One of the funniest was from the movie Romancing the Stone where actress Kathleen Turner couldn’t find a tissue to blow her nose so she used the sticky note which said “Buy tissues” to empty her nostrils.
     You may want to put some reminder sheets around your business or in your employee’s weekly paycheck envelope. The message can be inspirational or instructional. Call it a cheat sheet if you’d like – you might be cheating your competition out of a good idea.

     Do we use cheat sheets in our business? That term brings up memories of sitting near the back in Spanish class and observing many students surreptitiously referring to small lists of vocabulary. It is an unpleasant memory because so many were harming themselves, and because they were raising the grading curve. (I assume most of them went into public service, and that is the reason public policy is so bad.) I earned my low Spanish grade honestly, and am proud of it.
     We do use checklists – another form of cheat sheets. We have computer printed checklists for materials and procedures for attic heat pump installations, closet heat pump installations, preventative maintenance, and product features.
     My workers inform me when a truck-stocked item is low, that I write it in a pocket notebook – yet another type of cheat sheet. The result is dramatically reduced incidence of being on the job without a necessary part.
     Our productivity is extremely high, so there is money left for big (inspirational) bonuses on most jobs.

David Green
Green Electric
New Braunfels, Texas

If you enjoyed his last book, the NEXT Contractor, you’ll enjoy Profit Tips 1.1.1. even more. The price is $14.95 plus $3.75 S&H. John is taking orders right now at his website ( — click on ‘Profit Tips 1.1.1.’ You can order using PayPal and be assured of getting the copies fresh off the press. If you choose to order via check, the address is at the website, too. Order TODAY!

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