Radiant Heating and Cooling:
Questions? . . . and Answers!
- How does radiant heating and cooling work?
A radiant ceiling panel is used. It is placed behind
the ceiling drywall, plaster or paneling.
Warmed water circulates through panel piping in the ceiling, radiating warmth
to the space for
heating, and cool water circulates through the same panel in the ceiling, absorbing
heat from the space for cooling.
- What Equipment is used to heat and cool the building?
The most common arrangement is to use a dual function packaged boiler
for heating and domestic hot water production. A packaged chiller is used to
chill the water for cooling. In some cases it makes sense to use a reversing
air source chiller.
- Can I use a geothermal heat pump to heat and cool my
radiant building?
Yes. Geothermal heat pump systems work very well with radiant panel heating
and cooling systems. The low temperature heating and high temperature
cooling design of the radiant panel system helps the geothermal heat pump to
operate efficiently.
- Is a radiant heating and cooling system efficient?
A radiant heating and cooling system can be more efficient
than a forced air system. The mechanical equipment is very similar, but the
cost to operate a pump instead of a blower motor to distribute the
conditioning energy is less, and duct losses are generally less than back
losses from the radiant panel. In addition, a radiant heated room can be comfortable at a lower temperature, and a radiant
cooled room may be comfortable at a higher temperature when compared to a forced air conditioned space.
A well designed radiant panel heating and cooling system can use less energy
than a forced air system for the same space. However many people choose to
operate their home for optimum comfort and therefore the operating cost may
not be much different. A badly designed radiant system can use more energy than a well designed forced air
system.
- Are radiant ceiling panels only for new construction?
Radiant heating and cooling can be installed in new
construction or retrofitted into existing buildings. In some cases it may easier to
condition an existing building with a radiant heating and cooling system
rather than a ducted forced air system. In most cases the ceiling is not a
decorative element in the building design. For new construction the ceiling
is lowered 5/8" and in a retrofit, the ceiling is lowered a 1 1/8"
and sheet rocked. The architectural
impact on the building design is minimal in most cases.
- Do radiant ceiling panels need to be horizontal?
Radiant ceiling panels can follow any ceiling contour the building designer
desires. Radiant heat (and cold) travels in straight lines at the speed of
light. An object which cannot "see" , or is "shaded"
from the radiant panel will be cooler in the heating season (and warmer in
the cooling season) than objects in line of sight of the radiant panel. For
instance a canopy on a four poster bed would shade anyone sleeping on the
bed from radiant heating (or cooling).
- Is radiant conditioning more comfortable
than a forced air system?
Most people are more comfortable in a radiant conditioned space. There are
no drafts in a radiant system. There is no noise from a properly designed
radiant system. Heating and cooling system
design and individual preference can make a big difference in perceived
comfort.
- Is a radiant ceiling conditioned building responsive?
A radiant ceiling conditioned building responds very quickly to thermostat
inputs and begins to achieve comfort in a few minutes. There is not much need to anticipate
occupancy, to pre-condition a building before it is to be used. This is not
true for a radiant slab building where it may take several hours to achieve
comfort. An air conditioned building may take 30 minutes or more to reach
comfort depending on the difference at the start of the pre-conditioning
cycle.
- Is heating from the ceiling uncomfortable?
Heating from the ceiling resembles the way the sun heats the earth. However
the ceiling surface temperature is barely warm, and the furniture and other
surfaces approach the ceiling temperature in a few minutes. If you notice that
the ceiling is uncomfortably warm, then the supply water temperature is too
high, and should be set a little lower. This lower temperature will result in
a longer on cycle and fewer starts for the boiler, resulting in greater
economy as well as greater comfort. I heard from a bald man that his scalp can
get chapped in a ceiling heated room.
- Is Humidity a problem?
It all depends on your location. Radiant panel systems shall never be
operated to dehumidify the
indoor air. In a hot humid climate, a forced air dehumidification system
will be required. In a hot dry climate dehumidification will not be
required. In moderate humidity climates, controlled ventilation, or
mechanical dehumidification will be used.
- What about mold?
Mold grows in damp locations. Dampness is created when
water leaks or condenses on surfaces. Condensation is a concern in radiant
cooling systems. Cooling system design and controls prevent operating conditions which produce condensation. Mold problems will be the same as or less
than in traditional air conditioned buildings. A properly designed and
operated radiant panel cooling system will not promote mold growth.
- How will I know that my radiant heating and cooling system is working?
Radiant heating and cooling systems are silent, and do not create drafts.
You might be able to hear the boiler or chiller if you listen closely, but
they not in the inhabited space and operate intermittently. The best way to
understand it is, if you are not uncomfortable, it is working.