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Introduction to SmartZoneTM … a Rising Star

XCI Network Thermostats and Zoning are cost effective solutions to poor room-by-room temperature control and expensive utility usage.  XCI Controls distributes computer-controlled thermostats that have proven to be popular alternatives to over-priced building automation systems in the light commercial market.  XCI Electronics engineers, having years of experience in HVAC controls engineering, recognized a need to design and produce superior, cost effective zoning systems.  We focused on three things: Simple to install, service without a screwdriver or a voltmeter and allowing our customers to enjoy the comfort and convenience of a zoning system without realizing they even have one.  “SmartZone™ is a very exciting announcement by XCI Controls,” offered Greg Talley [XCI National Sales Manager] “Our operation is right here in Texas.” 

 

In the past few years, large controls companies have introduced new zoning systems, spending hundreds of thousands of dollars in advertising.  These companies realized as XCI does, zoning is a highly desirable accessory within a relatively mature and competitive HVAC industry.  The zone controls specialists at XCI are looking forward to discussing the things they have learned that will help you make money in this emerging market. 

 

“At XCI Controls, the goal is not only to provide a product that is simple, serviceable and customer friendly, but we also understand how to better serve our dealers and contractors,” stated Talley.  “We know that you want to be trained…we will come to you.  We know you want a rep. that will answer the phone… we will.  We know you want technical support when you are standing on your head in a 140 deg attic with a flashlight in your mouth, sweat dripping on your volt-meter and talking on a cell phone that has been dropped a few too many times… our people understand.”

 

If you are installing one zoning system per hour or one zoning system a year, take a look at SmartZone™.   An XCI sales rep. can come to your office with a demonstration board, leave you a complete catalog and give you the name of the nearest distributor.  XCI stocks for the distributor and the distributor stocks for you. 

 

SmartZone-4TM a Zone Control System for the 21st Century

 

Yesterday’s Technology is Being Replaced by New Ideas

It used to be that zone control was as crude as turning off individual radiators or installing window air conditioners for each room.  Those methods were costly, unsightly, and largely impractical.   Modern buildings require modern zone control systems that will work invisibly to provide clean, healthy, and comfortable heating and cooling exactly where the customer wishes.  New technologies and ideas available today enable zone control systems to offer more features and better comfort than ever before.  Zone control manufacturers who have kept up with technological advances are offering systems that include an array of new solutions that weren’t available even a year ago.

 

Supply Air Temperature Adjustments

When only a few zones are open, excess conditioned air called bypassed air should be re-circulated into the return plenum instead of being routed to a dump zone.  It is inefficient and often ineffective for an HVAC system to dump as much as 70 per cent of cold or warm air into another part of the building – the practice when using a dump zone.  For maximum efficiency the air should be re-circulated through the system.  Using this re-circulated bypassed air as entering air can cause extreme supply air plenum temperatures if the bypassed air is not monitored and accurately controlled.  Older systems use temperature sensors in the supply air plenum that have only one or two predetermined set points for supply plenum temperature management and do not allow appropriate run times in locales with humidity extremes.  “We solved the problem by including electronic limit controls in the sensors in our SmartZone control systems,” said Greg Talley, vice president and national sales manager at XCI Controls.  “It works with push button adjustable set points in one degree increments.  This type of sensor monitors and delivers accurate supply air temperature regardless of relative humidity.” 

An added benefit of electronic limit control is intelligent second stage operation.  It allows for staging based on supply air temperature rather than using a simple timer to activate the second stage.  Equipment staging should be based on supply air temperature over time, not just a predetermined time period.

 

The Control Panel – The Heart of the System

Most of the technological advances in leading edge zone control systems are found in the control panel.  Control panels should be evaluated in four categories: Installation, Operation, Service, and Ease of use.

 

Installation

Modern control systems are designed with the installation/service contractor in mind.  They include such features as quick-connect screwless terminals to eliminate the tedium and wasted time involved in  making connections with a screw driver.  Panels and cases are designed for easy installation, as well.           

In addition to easy connections, our SmartZone systems are designed to operate with gas, electric, or heat pump system, allowing for considerably fewer products to inventory and keep track of.  The controller configures easily to virtually any system.  This flexibility carries over to the thermostats because modern systems accept all four- and five-wire thermostats, giving the contractor a large choice of products to choose from.

 

Operation

Modern second stage operation has already been discussed but other features of today’s zone control systems also contribute to efficient and cost-effective operation.  Fresh air damper control from 0 to 60 minutes per hour is built in, eliminating the need for a separate piece of hardware.  Modern zone panels monitor and control all of the functions of the system – heating, air conditioning, supply air temperature, thermostats, two-stage operation, and fresh air and supply.  The correct purging strategy in modern systems starts immediately after all calls are completed.  After finishing the last call, the system should close all dampers and purge strictly through the bypass duct.  Non-calling zones should never receive conditioned/purged air.  Since no cooling or heating equipment is running during the purge, the supply air temperature will move to a neutral temperature during a purge cycle.

 

Service

One of the most impressive differences between old zone control designs and those of the leading edge systems of today is the ease of service.  Today’s systems eliminate the need for the technician to wander around the building looking for problems.  “We tried to include everything we thought would make the contractors job easier,” said Talley.  “They have full displays for diagnostics right on the control panel.  The panels show what zone thermostats are calling and what equipment mode is running.  They feature LED indicators for every thermostat terminal. The controllers also indicate when dampers are being powered and in what direction and they show if the controller is receiving the call correctly.”  The end result is considerably easier and more efficient service.

 

Ease of Use

The one who ultimately benefits from these leading edge advantages is the customer.  With a modern zone control system, all the customer needs to do is set the thermostats.  Everything else is invisible and automatic.  The only one who needs to look at the control panel is the technician.  Companion products to the newest zone control systems offer even more advantages to the customer – as an example, the ability to set all thermostats from a personal computer.  By incorporating network thermostats into the zone control system, the customer gains complete flexibility through a Windows® based program.  They can monitor and make changes from a remote location. Today’s zoning systems have reached a level of technology that includes electronic limit control for supply air, a second stage that activates when demand dictates, ease of installation, ease of operation, and comprehensive diagnostics.  Put together, these new ideas offer numerous benefits for both the HVAC contractor and the customer.

 

What is a Residential Zoning System?
A zoning system is made up of a controller that receives information from Zone Thermostats in multiple locations.  The controller then gives commands to HVAC equipment and specific Motorized Zone Dampers in order to control temperature in each of the thermostat locations.
 
Why do I need a Zoning System?
  • Based on the comfort temperature of the occupant… individual people are comfortable at different temperatures for different reasons.
  • Orientation to exterior loads… on a cool morning the east sun will shine on rooms that can cause cooling to be required, yet in rooms on the west side, no cooling or even heating might be required to maintain the same temperature in both spaces.
  • Upstairs vs. downstairs… heat rises.  Any heat that is gained throughout the building will try to accumulate in the upstairs area.  This fact means that cool air remains in lower areas.  The stairwell in some town homes with as many as four small floors will thermodynamically operate similar to a chimney.  As the outside temperature becomes more extreme, this temperature differential will increase.  A zoning system operated by a thermostat on each floor will maintain the correct temperature on each floor.
  • Usage of a room… some rooms have a specific use that requires more conditioning than others.  An example is an exercise room.  When this room is in use, the occupant may require cooler temperatures than normal because exercise makes the room seem hotter than normal.
  • Appliances in a room… modern kitchens may have large heat producing cook-tops, ovens, bread warmers, dish washers, etc.  These appliances can overheat the kitchen, while the occupant may be doing work such as stirring, mixing and cleaning.  A zoning system with a thermostat in the kitchen will keep the kitchen comfortable, yet not overcool other areas
  • Exhaust equipment… again, modern kitchens are a good example.  Some exhaust systems over a large gas range can exhaust the conditioned air in a matter of minutes.  Without a makeup air system, the exhausted air gets replaced with outside air that may not be fully conditioned.  A zoning system will allow these specific areas to be reconditioned to the comfort temperature required by the thermostat in that area.
 
What is a Zone Thermostat?
Multiple thermostats are placed in specific areas that need control based on temperature variations throughout the building.  Each SmartZone system can have 2, 3 or even 4 thermostats that control different areas in the building.
 
What is a Zone Damper?
Supply Air Motorized Dampers are air stopping devices placed in the duct system that open to allow air into a specific area or close when that area does not require conditioned air or ventilation.
Bypass Damper is also an air stopping device that is placed in a duct that is usually directly between the supply side and the return air side of an HVAC duct system.  The bypass damper is designed to allow any excess air pressure to escape from the supply side of the system to the return air side.  This pressure, if not controlled, can cause air noise from the supply air outlets.
 
Can I use a zoning system without a bypass damper?
Any zoning system larger than two equally sized zones should have a bypass damper.  The bypass air should be applied into the return air plenum.  This allows a normal duct system to be applied and the use of the excess air to precondition the return air.  Any time air is bypassed into the return air plenum, the system must include a supply air sensor.  There are certain specific 2-Zone applications where a bypass might not be necessary.
 
What is a Supply Air Sensor?
The supply air sensor (SAS)- is a probe placed in the supply plenum that monitors the supply air temperature.  The temperature of bypassed air used as air that is reentering the equipment can cause extreme supply air temperatures.  The SAS, in conjunction with other electronics on the controller does not allow temperature to become too extreme so that the equipment can run safely and reliably.
 
Does a zoning system control humidity?
A zoning system will control humidity as a byproduct of controlling the sensible temperature in each zone.  In a single zone system that may even be equipped with a humidity-sensing thermostat, the system still only has one point of control.  With a zoning system the building has several points of control.  Any time even one zone is calling as a result of a sensible call, humidity is also being removed in that area because in the cooling mode dehumidified air is being applied or in the heating mode, the air temperature is being raised without adding moisture to the air, thus decreasing relative humidity in the zone.
 
Can a zoning system save money on utility bills?
  • Certain buildings use less power when a zoning system is installed.  If all or most of the thermostats are set in an unoccupied temperature, only the thermostats that call will require conditioning.  This allows air to be applied only where necessary to maintain temperature in the specific calling zone.  Excess air is bypassed through the bypass damper back to the return air plenum.  This air is mixed with the return air as it enters the apparatus.  The bypassed air effects the entering air so that air supplied from the apparatus is cooler or warmer than it normally would be if return air only were being conditioned.  The supply air is able to condition the calling zones with cooler or warmer air than normal, thus changing the zone’s temperature relatively quickly.  The zone is then satisfied and the system is turned off, saving energy.
  • In other instances there will be no appreciable difference in energy savings because if all zones are set at a comfort temperature the system may be opening and closing zones based on the thermostats’ demands.  This may amount to about the same run time, however, comfort is much more achievable as there are thermostats in each space monitoring that space temperature.
 
What is a dump zone?
Some zoning manufacturers advocate a dump zone… WE DO NOT.  A dump zone is an area in the building where the bypassed air may be applied instead of applying bypassed air back into the return air plenum.  This can be a large quantity of very cool or warm air that is completely uncontrolled.  Since the bypassed air is a function of supply air dampers that are closed, thus causing excess air to be available, there are no conditioned areas where this excess air should be dumped in order to get rid of the excess pressure in the system.  This is largely a waste of energy and in most cases will effect zones that are satisfied so that they become unsatisfied and call for either heating or cooling.  Uncontrolled dump zones will also cause equipment to run longer because the wasted energy should be used to precondition the entering air so that the zoning system is as efficient as it can be.
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