LAARS Rheos+ RHHV - Install and Operating Manual - Manual (Page 17)

LAARS Heating Systems Page 16
4B.3 Water Flow Requirements —
Water Heater
In a water heating application (an open system),
new water is constantly being introduced. With the
new water comes a fresh supply of minerals that can
be deposited on the unit’s heat exchanger. This is
commonly known as scaling. The amount of minerals
will depend upon the hardness of the water. Water can
also be aggressive, and can erode metals, including
copper, if the water is moved too quickly. Pump sizing
for the Rheos+ water heater is based upon the hardness
of the water. The water flow is kept high enough
to prevent scaling, but low enough to prevent tube
erosion. For extremely soft or hard water, cupro-nickel
tubes are available. Contact a LAARS Representative
if you have questions or concerns about water quality.
The Rheos+ water heater has an internal mixing
system that ensures that the condensation does not
occur on the finned copper heat exchanger, with
heater return temperature down to 50°F (10°C). This
system, that consists of automatically actuated
and linked valves, is set up at the factory, and is
non-adjustable. The return water goes through the
stainless steel heat exchanger, then to the mixing
system. (see Figure 7).
Figure 4 - Hydronic Piping - Multiple Boilers
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