Solar Consultants Drainback Solar User Manual

Drainback Solar Water Heater
Internal Heat Exchanger Solar/Gas Water Heater
This manual describes our drainback type solar water heater with the
following characteristics:
• Sealed solar fluid loop (no need to top up fluid seasonally as with systems that
are open to the air.)
• Self-protected from freezing or overheating with or without electric power
being on.
• Allows extra collectors for space heating.
• Backup is built in to the upper portion of the water heater.
• Uses industry-standard circulators (pumps). Other brands can be substituted
for replacement without system redesign.
1. Components
The solar loop of the system consists of a small (10-20 gallon) drainback
reservoir to store solar fluid, a pressure relief valve, a pump to lift the fluid and
move it through the collectors, one or more thermal collectors, and the heat
exchanger built into the Phoenix water heater. The solar fluid is either plain water,
water with a pink-tinted anti-corrosive buffer added (if the drainback reservoir is
not stainless steel), or a propylene glycol antifreeze mixture (if the reservoir is in
an unconditioned space.) A boiler drain, sight glass, and fill plug are provided for
maintenance.
The potable, or domestic hot water is stored in the 80- or 120-gallon water
heater and does not mix with the solar fluid. A separate set of fittings provides
domestic water for space heating, either into an open hydronic system or via an
external heat exchanger/pump system. The system may include a tempering
valve to manage the outgoing water temperature.
The solar pump is controlled by a differential temperature control, typically
a Steca TR0301. The control compares a temperature sensor at the top of the
using Phoenix "S" model Hybrid
User's Manual
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