By Bob Baker

The past two issues we have been following the planning and install of a zone control system in a 3,000 square residence in West Central Florida. This issue, we will review the startup and initial results.

Initial Startup

Once everything was in place, I restored the power to the system and turned on the switch on the zone control panel. It was a warm day and the family room zone called for cooling. The first thing I noticed was a lot of noise. Only the damper to the family room was open and I had a lot of air noise. I quickly realized that all of the individual supply grill dampers were still balanced for 2,000 CFM distributed throughout the entire home. I quickly grabbed a ladder and opened all the grills to maximum (including a couple that were completely closed?). Things immediately quieted down nicely.

I then went around the house setting each thermostat. Everything seemed to be working well and the system cycled on and off as expected. Comfort was good and temperatures even throughout the home for the first time ever.

Trouble at Changeover

The next morning, things had turned cold, as they will at this time of year in Florida. The place was freezing and the system was running. A quick glance at the indicator lights on the control panel revealed that the upstairs zone was on and the heat pump was energized in cooling mode. After bypassing the control panel to get some heat going, I called Carl Peterson at Zonex. After listening to my problem, Carl replied, "Your forgot to remove the cooling anticipation resistors and the electronics in the control panel are getting false signals." I responded that I have removed the ones in three of the thermostats but the fourth didn't have one. He advised me to check again. On closer inspection, it did have one which was cleverly hidden and which I proceeded to cut out.

I hooked the system back up and things were off and running. After a couple of days, it was apparent that comfort in the home was better than ever before but the zone that consisted of the two upstairs bedrooms and adjoining bath and hallway was still not holding a consistent temperature.

The Importance of Adequate Return

These two bedrooms did not have ducted returns and relied on door undercuts for air return to the return grill located at the top of the stairs. When the air flows in that zone were checked, it was found that less than half of the air that should be delivered to that zone was actually returning to the air-handler. The door undercuts were simply inadequate to provide the needed air return.

In addition, the thermostat controlling that zone was the former thermostat for the entire system located above the return air grill in the hallway. Given the limited return from the bedrooms in the zone, it was sensing air temperature from the floor below as well as from the served zone. When the doors to the two bedrooms were left open, everything worked fine but closing even one of the doors led to significant temperature swings in that zone.

The obvious solution was to install ducted returns from the two bedrooms, which was not possible without major building modifications. As a compromise, it was decided to install return grills in the ceiling of each of the bedrooms and duct them to a grill in the hall ceiling that would serve as a pressure relief. The fact that that grill was located above the zone thermostat would assure that the temperature of the air from the bedrooms would provide the major input to the zone thermostat. This option has worked very well. This illustrates the vital importance of good air return from each zone to the success of a zoned system.

Economy of Operation

Normally, it is recommended that all zone thermostats be set at the desired temperature and left alone. Wide swings in individual zone temperatures such as turning the bedroom zone off during the day then on prior to bedtime do not really save any appreciable amount of energy because the heat load that has built up in the area requires so much to overcome. In this case, we decided to leave the thermostat serving the living/dining area off except when the rooms are actually being used. This area has relatively little exposure to the exterior as it is between the master bedroom and rest of the home. It was felt that it would experience little heat gain from outside and because of the limited use of the area, considerable savings of energy may be available. In the heat of mid summer, this may not be possible but so far is not noticeable.

After two full months of operation consisting of unusually cold weather and several weeks of typically warm days, the results are impressive. During the first month records for cold were set in the area yet power consumption was on a par with the prior year. The second month, power consumption was about 60% of the prior year. These numbers are rough as there has been no adjustment for degree-days or other factors.

We will continue to monitor temperatures, airflows and power usage and do a follow up report after the system has been through all seasons and conditions. Based on the experience to date, however, we encourage any contractor who has not yet offered zone control to investigate the technology and begin to offer these systems. Your customers will thank you and it can be a source of excellent profit margin.

Mr. Baker's field of expertise is the control of contamination in air-conditioning and ventilating systems by mold, mildew and bacteria. He writes and speaks frequently about the efficacy, legal risks, and regulatory issues involved in various control strategies. He serves on ASHRAE Technical Committee TC 2.3, TC 2.4, TC 9.8, and Sampling of Airborne Particulate Concentration in Commercial and Residential Buildings GPC 17P. He also serves as a member of ASTM D22.06 (Indoor Air Quality) and is on the Board of Directors of the Indoor Air Quality Association and the Florida Public Health Foundation. Because HVAC applications encompass new uses from an U.S. EPA regulatory standpoint, Mr. Baker works closely with the EPA and industry groups, including serving as the chair of the IAQ committee of the Consumer Specialty Products Association, to help formulate policy in this area.

Bob Baker is Chairman and CEO of BBJ Environmental Solutions, Inc., a company specializing in providing clean air through environmentally responsible products, such as BBJ MicroBiocide , BBJ Micro Coil Clean , "FreshDuct Odor Eliminator ", and BBJ Mold and Mildew Remover™ as well as the revolutionary new Power Coil Clean™. For additional information, Mr. Baker can be reached at (800) 889-2251 or through the company web site at http://www.bbjenviro.com.