Technician’s Guide and Workbook for Zoning Section 9: Zoning System Options

Adding Zones to Existing Systems

EXISTING HOME CONDITIONS EX 1 A homeowner, wants to know if a zone can be added for his master bedroom and for the office in the basement. Complaint: home is drafty and has hot and cold spots, the master bedroom is not comfortable, and the basement office is always uncomfortable. The technician’s brief and basic survey reveals the following:

Home 1 Conditions (1) Two single-stage HVAC systems, one for the upstairs bedrooms located in the unconditioned attic, and one for the basement and first floor located in the basement. First floor thermostat does not control basement temperatures well. Second floor windows are east and west facing in some rooms so, the solar gain loads are not compatible. Especially since the controlling thermostat is in a center hall. The duct work is sealed, and the attic has R-6 insulation. There is room for adding dampers and for working on or changing the duct sizing.

Home 1 Conditions (2) Returns or transfer grills are not present in every room. No branch dampers were installed in the system for air balancing (a telltale sign there was no air balancing done). No design record for: Manual J load calculation, Manual D duct design, Manual S equipment selection. No record of duct leakage testing. No startup data for the equipment. No maintenance records other than outdated initialed filter change sheets.

Home 1 Recommendation At this point the technician can recommend starting with a standard maintenance service on the two HVAC systems so the equipment’s basic condition can be documented. However, unless the homeowner wants to hire the company to do the design calculations, duct leakage testing and to balance the existing system (if the duct is sized correctly), simply adding zone dampers to the system as is without a complete airflow analysis is not advisable.

EXISTING HOME CONDITIONS EX 2 A homeowner, wants to know if a zone can be added for his bonus room and if auxiliary heat can be added for the office in the basement. Complaint: Bonus room was finished over the garage without adding a HVAC system or ducting. Basement office is always too cold and has no supply air duct. The technician’s brief and basic survey reveals the following:

HOME 2 CONDITIONS (1) A homeowner, wants to know if a zone can be added for his bonus room and if auxiliary heat can be added for the office in the basement. Complaint: Bonus room was finished over the garage without adding a HVAC system or ducting. Basement office is always too cold and has no supply air duct. The technician’s brief and basic survey reveals the following:

HOME 2 CONDITIONS (1) Two single-stage HVAC systems, one for the upstairs bedrooms located in the unconditioned attic, and one for the basement and first floor located in the basement. No heating or cooling in the basement. The whole basement is a below grade, with uninsulated concrete walls and with an uninsulated slab floor. It also has with two south facing double pane windows in window wells.

HOME 2 CONDITIONS (2) The bonus room is over the garage and was insulated with R-11 in the walls, and R-21 in the cathedral ceiling and under the floor in the garage ceiling. As reported by the owner there is no heating or cooling in the room. It has one double window on a north facing wall. No design record for: Manual J load calculation, Manual D duct design, Manual S equipment selection. Regular maintenance records for the existing equipment are on site.

HOME 2 Recommendations At this point the technician can let the home owner know that a load calculation will need to be done for the two areas, so the equipment options can be provided.

Equipment Based Zoning Options Ductless Mini-Split Single Package Equipment Convective and Radiant Heat Central Chillers

Ductless Mini-Split

Mini-Split Zone Piping (1) Basic Heating or Cooling Piping Diagram

Mini-Split Zone Piping (2) Two Pipe With a Pipe Header Distribution Box

Mini-Split Zone Piping (3) Three Pipe System with individual Mode/Distribution Boxes.

Single Package Equipment Packaged terminal air conditioners (PTAC) and packaged terminal heat pumps (PTHP) include through the wall and window units.

Convective and Radiant Heat Convective and radiant heat can be provided by water, steam or electric resistance systems.

Chillers Chillers are getting smaller, and some are now available for residential use. Radiant, panels, fan coils, and hydronic wall, ceiling and floor applications may be included in zoning designs. For radiant heat transfer applications, humidity control must be included in the system’s design. Balancing hydronic systems and additives to prevent freezing are covered in Manual B.

Hydronic System Basics The previous two power point slides have, hydronic distribution systems included as part of the design package.

Selecting Grilles and Registers (1) Grilles and registers are usually one of the least expensive parts of the HVAC system. Grilles, registers and diffusers are a very small but vital portion of the HVAC system, and should be selected and examined with the same scrutiny as the other portions of the system.

Selecting Grilles and Registers (2) For more information on diffusers, see Manual T Air Distribution Basics for Residential & Small Commercial Buildings or, The Technician’s Guide & Workbook for Quality Installations, covers the grille, and diffuser selection basics.

Field Notes The homeowner’s complaint is simple, the play room and guest bedroom located in the walkout basement were always cold. After noting the location of the electrical panel in the corner of the basement, and noting there was room for a few more breakers in the 200 amp panel, the technician recommended creating two new zones by putting in electric baseboard heaters.