| Overall
Design Considerations |
(
We recommend only Closed Loop System.)
The Thermomax Collector
transfers the heat to a copper pipe in the manifold via
thermal clamps. This eliminates collector contact with the
fluid (water), provides a double-walled heat exchanger and
allows the manifold to accept city water pressures. |
(All
weather conditions - Multiple application)
A closed loop system uses a transfer
fluid, usually non-toxic propylene glycol, to transfer the
heat from the collector to a heat exchanger through a
pressurized closed loop. As well as controller and pump this
system needs a heat exchanger or a tank with a coil, expansion
tank, pressure relief valve, air vents and possibly a check
valve to stop night time thermosyphoning. The glycol provides
excellent protection against freezing.
It is possible to power the pump directly by photo voltaic,
eliminating the need for a controller and making the system
truly independent. If the system can be designed with the
manifold below the heat exchanger, the system will
thermosyphon, and the pump can be eliminated as well.
A closed loop system is useful where more than one application
is to be heated, switching between heat exchangers using
simple valves and controls. In areas where extreme freezing
conditions are experienced it is sometimes the only option. |
Closed
Loop System |
| Commercial
and Industrial Systems |
(Large
volume of Hot Water Usage)
Thermomax Collectors are being used for
offices, apartment complexes, commercial buildings, hospitals,
airports, restaurants and hotels. This is a diverse list of
applications, but they all have one thing in common - they all
use a large volume of hot water. Our basic guide for the
Design of Commercial or Industrial Size Solar Heating Systems
must be verified and approved by a licensed engineer according
to local requirements. The responsibility rests by your
M&E engineers. |
(Moderate
weather - hard water - single or multiple applications)
A domestic hot water or multiple
application drain back system requires a heat exchanger, a
vented tank and a high lift pump. It is suitable for areas
with hard water.
Single application pool or spa systems, utilizing the existing
pump, are economical to install as the collector can accept
the pool or spa water directly. |
Drain
Back System |
| Drain
Down System |
(Moderate
weather - single application)
This system has a special drain
down valve that, when activated, allows potable water to fill
the collector at city pressure. A small pump circulates the
water from the bottom of the tank through the manifold,
returning it to the bottom of the tank where, being warmer, it
rises. When deactivated, the flow and return to the tank are
sealed and the water from the manifold drains away. This
protects the collector from freezing and eliminates night time
losses from either thermosyphoning or recirculation. |
(Mild/moderate
weather - single application)
The open loop system has
potable water at city pressure in the collector at all times.
Below 42°F the controller periodically cycles the pump and
the moving water prevents the piping from freezing - a
recirculation system. Additional freeze protection can be
provided by a temperature activated drip valve at the
collector, and plumbing the pipes to encourage
thermosyphoning.
Although some heat can be lost due to the recirculation
process, Thermomax keeps these losses to a minimum as it's
unique design prevents heat escaping from the collector. In
areas that do not freeze the recirculation feature can be
omitted.
For both drain down and open loop systems a special fitting
can be used to connect the flow and return through the drain
of a standard tank, or the drain and bottom element holes can
be used. |
Open
Loop System With Recirculation |
| Gas
Backup |
Traditionally
domestic hot water solar systems have had an electric backup.
It has been relatively easy to situate an electrical element
of sufficient power the correct distance from the top of the
tank to give adequate backup. With Natural Gas or LPG taking
over the nations water heaters, we need to look at how to get
the best efficiencies from solar systems using a gas backup. |
Traditionally
domestic hot water solar systems have electric, gas, or oil
backup. The combined Thermomax system with a wood burning
stove as backup offers the ultimate thermal energy
independency. |
Woodstove
Backup |
