CLICK: Access the author’s past SOLAR TODAY articles detailing how to
install a sand-bed solar radiant system and a case study of his own solar-heated net-zero-energy home: solartoday.org/ramlow
In high-mass solar heating systems, a sand bed typically 2 feet ( 61 cm) deep covers the building’s
entire footprint. A gridwork of pex tubing is installed in the sand bed, with solar-heated fluid pumped
through. A concrete slab is poured over the compacted sand, and heat radiates through the floor and
into the building.
(30- by 61-cm) aluminum plate with two strips
of three-eighths-inch-thick plywood attached to
the top side, covering the whole aluminum plate
except for a three-eighths-inch-wide groove running the length of the piece. The track plates are
attached to the top of the floor and aligned so the
grooves create a long channel. The room’s entire
floor is covered with the track plates, creating a
parallel grid of grooves. You’ll snap pex tubing
the same depth as the plywood into the grooves,
creating a flat surface that can be covered with
tile or hardwood. In a retrofit, installing track
plates will require all doors and trim to be cut to
accommodate the new floor height.
Radiant wall panels are another excellent way
to distribute solar heat in a building, with many
fashionable, affordable products on the market.
These panels come in countless sizes. When sizing the panel for a room, calculate the heating
needs of the room on the coldest day of the year
and match the British thermal unit (Btu) output
of a panel or panels to meet the calculated load.
Be aware that the Btu output of a panel is directly
related to the temperature of the heat-transfer
fluid passing through it. For solar heating systems, figure that the average fluid temperature
coming out of a solar storage tank during the
winter in northern climates will be around 120°F
( 49°C). For places outside the northern states, a
good winter benchmark is 140°F ( 60°C).
Installing panel radiators in a retrofit situation is remarkably easy. Most hang on brackets
attached to the studs in the wall. Running the
piping is a little more difficult, but note that these
panels can be mounted either on interior or exterior walls. Much of the hidden piping can be pex,
which is easy to run.
designing for new construction
In new construction or major renovations,
we have all the retrofit options detailed above,
along with concrete-based floors, walls and
Get more Info
Solar Water Heating, A Comprehensive Guide
to Solar Water & Space Heating Systems,
by Bob Ramlow & Benjamin Nusz, New Society Publishers: arthaonline.com
Solar Hot Water Systems, Lessons Learned
1977 to Today, by Tom Lane, ECS Solar:
ecs-solar.com
Radiant Panel Association: radiantpanel
association.org
ceilings. We also have the option of using a sand
bed for heat storage with the concrete floor.
When it comes to water storage systems, the
most familiar radiant floor heating has pex tubing embedded in concrete floors. The tubing can
be embedded in a traditional on-grade slab or in
a lightweight concrete or gypcrete slab poured
over wooden subfloors. Concrete-based systems
are slower to heat up or cool down compared to
heat-emission-plate systems, but they retain heat
longer, making temperatures more stable in the
buildings they serve. Note that floor coverings
over radiant floor systems significantly impede
the systems’ heating ability. Any sort of covering
other than ceramic tile will act like insulation,
inhibiting the radiant waves.
Radiant walls and radiant ceilings are easy to
incorporate into new construction or in major
remodeling projects where walls or ceilings are
opened up. To create a radiant wall or ceiling,
track plates are installed directly into the studs of
an insulated wall or ceiling, and drywall is applied
over the track-plate system. Normally the track
plates are located in the middle section of the
wall, below where pictures hang. You do not want
to puncture the pex tubing that will be in the wall
when hanging pictures. Of course this is not an
issue if the radiant track plates are in the ceiling.
As a side note, we have two radiant walls
in our new home, which was featured in SOLAR
TODAY’s March/April 2008 issue (see “Warmed
by the Sun in Wisconsin” at solar today.org/
ramlow). These radiant walls are simply amazing. They’re completely undetectable and do a
fantastic job of heating the rooms in which
they’re installed.
I have saved the sand-bed system, my favorite
solar heating system, for last. High-mass solar
heating systems are great for new construction
and some retrofits. In these systems, a sand bed
typically 2 feet ( 61 cm) deep covers the building’s entire footprint. A gridwork of pex tubing is
installed in the sand bed, with solar-heated fluid
pumped through. A concrete slab is poured over
the compacted sand, and heat radiates through
the floor and into the building.
I’ve described sand-bed systems in both my
previous SOLAR TODA Y articles, as well as in my
book. Since 18 months ago, when I last reported
in these pages, a winter has passed and we continue to be impressed with the performance of
our sytem. We’re so impressed, in fact, that we’re
now retrofitting our 100-year-old farmhouse/
bed and breakfast with a sand bed. ST
