Hydronics
HYDRO-AIR SYSTEMS HAVE BEEN AROUND
for a long time…even hydro steam.
I remember the first time I saw a radiator
mounted inside of a plenum and I thought
“what the heck is this?” Back in the day,
when fresh air was deemed a necessity
(unlike today in our tight energy efficient
homes - ha!), ductwork would draw air
from the outside and heat it with these
duct-mounted radiators before delivering it
to the living space.
Not very efficient, but fuel was a lot less
costly back then, and the owners of these
homes weren’t shy of a few pennies. Times
have changed, however. Today when we
say hydro-air, we think of air handlers with
internal coils for heating and/or cooling.
VARIETY PACK
For the most part, hydro-air is a product
of the electric conversion market, when
electricity prices started to rise. Replacing
that old electric furnace and installing a
boiler with an air handler allowed versa-
tility when it came to zoning and potable
hot water.
Indeed, the ability to run additional
emitters off the boiler often led to systems
with multiple heat delivery schemes such
as warm air, convection and radiant. Entire
sections of the home could be heated by a
different medium, e.g. warm air upstairs;
radiant downstairs; baseboard in the base-
ment. And all of this with air conditioning
and endless hot water as well. The more
recent decades have seen an increased
demand for air conditioning, and for homes
heated with water, hydro-air is a very con-
venient solution.
One of the major differences between
air handlers and direct fired furnaces is the
quality of the air delivered to the home.
The heat exchangers in fuel-fired furnaces
are subjected to extremely high surface
temperatures, which tend to dry out the
delivered air. Whereas, with an air handler,
the heat exchanger never sees temperatures
above 180°F resulting in a much more
comfortable living environment.
INTRODUCING VARIABLE SPEEDS
The implementation of ECM technology
inHVACmotors has had a significant impact
on the efficiency of the equipment. We first
began to see ECM motors in air handlers
and condensing furnaces, which resulted
not just in increased motor efficiency but
also enhanced the performance of the
blower by compensating somewhat for
inadequate duct design. ECM motors make
a lot of sense for air handling equipment
because of the larger size motors needed to
move large volumes of air.
And more recently, we have seen the
introduction of ECM motors into the wet
side of the equation. All of the leading
pump manufacturers boast ECM circulators
- which begs the question of how best to use
this technology in a hydro-air application.
High-Performance
Hydro-Air
Variable Speed Motors Improve
Delivery of Conditioned Air
By Bruce Marshall, Emerson-Swan
22 • OIL
&
ENERGY
The Taco BumbleBee (Model
HEC2) is a programmable
circulator that uses Delta T
to increase efficiency and
improve comfort.
A Suntherm air
handler with heating
and cooling coils.
