Solar

Radco DBHX 6000 Series Drainback Heat Exchange Modules

Operate a solar water heating system by transferring solar energy to a storage water tank.

The Radco DBHX 6000 series drainback systems have these strengths:

• Allows most any solar collector and water storage tank to become a drainback system.
• Modular design translates to lower labor costs for installation and less space requirements for installation.
• Provides automatic and fail-safe freeze protection.
• Works well in most climates.
• Power is not required for the drainback freeze protection to work.
• Does not need propylene-glycol to protect from freezing temperatures.
• Low maintenance - No need for propylene-glycol or rust-inhibitor fluids translates to less maintenance requirements
• The closed-loop to solar panels protect the collector's fluid passages from mineral build up caused by "hard" water --where water contains an excessive amount of dissolved minerals.
• SRCC approved designs.

Radco has developed a mechanical-control package for drain-back systems. This Drainback Heat eXchange module (DBHX) is a factory-assembled unit which provides:

• a single-walled heat exchanger,
• collector fluid reservoir,
• solar collector fluid circulator pump,
• hot water booster circulator pump and
• a differential temperature controller unit

..assembled into one attractive module. Most any solar collector and any water storage tank can be combined to form a drainback system!

Principle of Operation

A drainback system works on the "drain back" principle. When inclement weather or nightfall shuts down the system, the water in the solar-collector loop drains back into an indoor fluid reservoir by the force of gravity. The water is pumped into the collector piping whenever the system is reactivated. Heat energy is not wasted in heating the solar collector (as in recirculating systems). Cycling on partly cloudy days does not dump energy (as in draindown systems) since the collector fluid is stored in an insulated reservoir. Drainback removes all water from the solar collector and piping whenever the solar energy collection process is not active. Freeze protection is automatic and fail-safe.

DBHX system schematic:

Components

• Accumulator Tank 8 and 12 gallon capacity, 14 gauge steel, constructed to ASME standards, fiberglass insulated, internal drainback orifice, filling and draining provisions.
• Heat Exchange Coil All-copper, single wall
• Differential Temperature Controller Solid-state, 115VAC, plug-in line cord, U.L. listed, adjustable high temperature shut-off, includes one sensor, 20°F on, 5°F off differential.
• Circulator Pumps 8 and 12 gallon DBHX Modules use identical pumps and are water lubricated, field repairable, low power consuming, U.L. listed, bronze or stainless steel body in potable water loop.

Engineering Data

Performance Data

Note: Single-wall heat-exchanger test data and results may differ due to varying temperature and flow conditions.

E.W.T = Entering Water Temperature
L.W.T = Leaving Water Temperature
Log = Logarithmic

SRCC Certified configurations

Radco makes solar water heating systems that meet specific industry certifications and compliances. These configurations use the Radco DBHX drainback module -- EDX 6002 or EDX 6005 depending on the specific parameters of each certified configuration.

SRCC Certified OG-300 systems with electric auxiliary heating

Drainback Heat Exchanger (Indirect Pumped Circulation) models:

• R-DBHX-8-65-D-40P
• R-DBHX-8-80-D-64P
• R-DBHX-12-120-D-80P
• R-DBHX-8-65S-40P
• R-DBHX-8-80S-64P
• R-DBHX-8-120S-80P
• R-DBHX-8-80S-40P
• R-DBHX-8-80S-40C

SRRC Certified OG-300 systems with gas auxiliary heating

Drainback Heat Exchanger (Indirect Pumped Circulation) models:

• R-DBHX-8-65-GD-40P
• R-DBHX-8-80-GD-64P
• R-DBHX-12-120-GD-80p
• R-DBHX-8-40-GS-32P