Frequently Asked Questions
How does HVAC zoning work?
What if I have several
ducts per zone?
01 A - How does HVAC zoning work?
HVAC zoning systems use
motorized dampers or flex dampers to move forced air (heat and cool) to
the occupied areas or to areas of your home or office where you have a
temperature problem (i.e. upstairs or the west side of a home). An
example would be in the winter time, you can heat the living area after
work until time to go to bed. Then at bedtime you can close down the
dampers in the living areas and send the conditioned air to the bedrooms.
Therefore, you will not be wasting energy dollars heating areas that are
not being used. Another prime example is in two story homes. Most of the
heat moves upstairs so it is a challenge keeping the upstairs cool and the
downstairs warm. A RetroZone system will eliminate this issue as well.
Generally, each zoning system will include flexible or mechanical dampers (at least one in each zone), thermostats for each zone, control panel for control of dampers and HVAC equipment plus a bypass equipment if needed. See our Zoning Packages (under Catalog tab) for examples of systems.
There are generally three types of zoning systems, Complete HVAC Zoning Systems, Slave Zones and a combination of a Slave / Complete Zoning System.
Slave Zones are HVAC zones where a thermostat or a switch directly controls the damper to simply close off airflow to an area, without controlling the HVAC system. This zone type is used in rooms/areas where exact temperature is not vital (i.e. in seldom used basements).
A Complete HVAC zoning system allows you to control temperature in each area/room that is it’s own independent zone. This requires a Control Panel, thermostats for each zone and at least one flexible or mechanical damper per zone.
You could also have a combination of both the Slave and Complete HVAC Zoning systems.
03 A - What equipment do I need for a HVAC zoning system?
You would need a
thermostat for each zone (you can use your exiting thermostat or get
matching thermostats), a control panel, the dampers or damper system, a
24Vac transformer and possibly a by-pass damper. You would need a damper
on every duct coming off your plenum (the box at the end of your furnace
with all the ducts coming out) and/or a
damper going to all the ducts in all the separate zones.
You can do this by
checking your thermostat to see what wires are HOOKED UP. Simply
take the cover off your thermostat so you will see the soldering,
circuitry and terminal hookups. You want to look at the terminal
hookups. If yours is like most you will have R, C or X, G, Y or Y1,
W or W1. If you have a heat pump you would also have either the O or B
hooked up (NOTE: these letters are abbreviations for the colored
wire used, i.e. R = red, G = green, Y = yellow, W = white, B = brown or
blue, O = Orange, C is different it is common) . If you have a multi stage
unit you would have W2 and Y2 as well. There are others, but that is
basically it. You should also know what size HVAC unit you have.
It is measured in tonnage (AC) or BTUs (heat).
Some HVAC units have
multiple speeds to help satisfy heat/cool demand faster. Multi speed
units can go to a higher fan speed depending on how long an area takes to
reach the desired temperature or based on the outdoor temperature. Retrozone carries all equipment needed for multi stage equipment zoning.
You need to know how your ducts are laid out. Best case scenario would be you have one main duct leading to all the other ducts for the area that you want to be zone 1 (downstairs), then the same for zone 2 (upstairs), etc. This is usually not the case, but if you do, you would only need 2 dampers, one for each zone. If you do not have this set up it is not a problem as our Air zone/Flexdamper system often has 5 to 10 dampers per zone.
If you do have several ducts serving any one zone, you should search out what ducts go where and what size they are. You either have round or rectangular ductwork, if round, measure the diameter, if rectangular, measure W x H. This needs to be measured directly on the ductwork, under the insulation. You should draw out a plan of your ductwork, noting the sizes along the way and showing the rooms they go to.
Find the furthest
“upstream” you can go on the ductwork and still get all the ducts you must have in
one particular zone area (i.e. You may be able to get several of the bedroom
ducts on one damper, assuming you are going to make all the bedrooms one
zone). Mark all these areas on your plan. This will tell you what dampers
are needed to complete your zoning as desired.
We would always recommend
using a State Certified HVAC Technician, however we have sold thousands of
systems to DIYers. Our systems all use low voltage electricity and come
with very readable installation directions. Those installation
directions are available on this site under the "Technical Support" tab.
It is a challenge to find
HVAC zoning info on the internet, but the installation guide we send with
the award winning Flexdamper System is complete. You can find this manual
on our web site under the "Technical Support" tab.
A zoning system is
traditionally sold to increase comfort in a home or office. However, by
heating/cooling a smaller portion of your home, at any given time, you
will save on energy costs. Zoning systems will allow you to heat/cool
only the parts of your home that are occupied at any given time of the
night or day. Plus the zoned areas have a faster temperature recovery
time, as all conditioned air is going to that zone. It very well could be
significant energy savings without giving up comfort.
It depends on if you use
the HVAC zoning system for energy savings or comfort. If used for energy
savings only, then you could save 20-40% of energy costs.
This is one of the best
benefits of a zoning system. You get the comfortable air where you need
it AND cut down on your energy bill. Compare it to other utilities that
are zoned in your home: Lights – you only turn on where needed, not the
whole house. Water – again, only where you need it. And Heating and
Cooling is a much larger portion of your energy bill each month. By
closing off the areas that are not used and putting more of that once
wasted air in usable areas, you are satisfying your comfort needs and
cutting the unit off quicker, saving more energy costs. More comfort at a
lower energy cost.
If you have one duct per
zone, you could do either the mechanical dampers (spring return or power
open/power close) or the Flexdamper System. If the ducts are easily
accessed, the motorized damper would be the more economical choice.
You would want to go with
the Flexdamper System.
The Flexdamper System is
the ORIGINAL RETROFIT and award winning solution to zoning existing homes
and smaller commercial applications. Anything you can do with a
mechanical/motorized damper you can do with the Flexdamper System. The
advantage of the Flexdamper System is it can easily be installed in very
hard to get to locations. You can install directly through the register or
through the plenum - and there is no need for the perfect cut required on
metal dampers. The Flexdamper System is also much more economical when it
is necessary to install several dampers per zone.
Flexdampers insert into
your existing ducts, from the register, plenum, or inline in the duct.
Since they are freestanding in the duct, they may be maneuvered around
corners or into tight spots. Flexdampers are connected to a solenoid
panel and pumping unit. When a solenoid is de-energized, the solenoid
switches to pressure, causing inflation, and shutting off airflow in the
duct. Flexdampers are connected to vacuum, causing positive deflation
with little or no restriction to airflow in the duct. Therefore, the
Flexdamper acts the same as a Power Close / Spring Open damper. The
bladders are made of military grade, non-expandable (not like a balloon)
urethane. These bladders actually can outperform mechanical dampers.
Remove any insulation then
measure the outside of the duct’s width and height. You would order by
these two dimensions. For example: If duct measured 14” wide and 10”
tall, your duct would be 14x10. The stated order of each dimension is important
– it should always be W x H. Rectangular Flexdampers (RFD) are ordered in
5 different sizes then field adjusted to custom fit the dampers. RFD
sizes go from 6x6 to 24x12. See the Rectangular Flex Duct sizing chart in
the Airzone Installation manual.
We can make virtually any
size damper. Call the Factory for unlisted sizes.
If accessible, very easily. You cut a slot in the side of the duct the height of the damper from 2” to 3” wide (depending on type of damper ordered). Slide the damper in the slot. Secure with some sort of weather stripping (if necessary). Screw in 4 sheet metal screws. Wire it up.
Rectangular Flexdampers (RFD) are field cut to size (as detailed in Airzone Installation Manual - available in our Technical Support section) mounted to the ductwork and attached to the plenum rated tubing.
Copyright RetroZone 2010