Lochinvar 000 - 500 User Manual

The required temperature rise and the standard pump
sizing are based on the heating of potable water with
chemistry within the specified limits.  Caution should
be used when heating water softened to less than 5
grains per gallon.  Many commercial water softeners
reduce hardness to 0 grains which may result in long
term problems in the system.  Softened water will
usually have a lower pH which can be aggressive and
corrosive causing non-warrantable damage to the
heater, pump, and associated piping.  

Corrosion due to water chemistry generally shows up
first in the hot water system because heated water
increases the rate of corrosive chemical reactions.
Follow the temperature rise recommendations when
heating soft water.  Unsoftened water with a hardness of
8 to 25 grains per gallon and/or total dissolved solids
not exceeding 350 ppm requires a higher velocity and
lower temperature rise.  As water is heated it becomes
less soluble.  The dissolved minerals and solids will
precipitate and collect as scale if water velocity is not
properly controlled.  Follow the temperature rise
requirements for unsoftened water.  Consult the
manufacturer when heating potable water with hardness
or total dissolved solids exceeding these specifications.
Heating of high hardness and/or high total dissolved
solids water may require a larger circulating pump, an
optional cupro-nickel heat exchanger and a revised
temperature rise specification based on the water
chemistry of the water to be heated.  

Decreasing the flow rate will reduce the erosion
process, however the heat exchanger should be
monitored to ensure the scale/liming process is not
made worse.  The unit should be placed on a
comprehensive inspection schedule until optimum flow
rates can be established.  Problematic water areas may
require heat exchanger inspection every two weeks.
The total scale accumulation should never exceed the
thickness of a piece of paper.  Should scale
accumulation exceed this thickness the flow rate will

need to be increased.  The tubes should not have a
bright shiny copper look.  This would indicate that the
erosion process has begun and the flow rate will need to
be decreased.  Once the proper flow rates have been
established the inspection intervals can be increased to
every 30 days, once a quarter, or to a bi-annual
inspection.  This procedure should ensure proper
operation of the unit as long as the water quality stays
consistent.

1.  The water heater/hot water supply boiler must be

connected to a properly sized pump  that circulates
water between the heater and storage tank.

2.   Pump is sized to heater input and water hard ness.

Care should be taken to size the pump
correctly.  See “Water Chemistry”, this page.

HOT WATER SUPPLY

COLD WATER SUPPLY

RELIEF
VALVE

LOCK-TEMP
STORAGE
TANK

DRAIN

RELIEF
VALVE

CIRCULATING PUMP

EXPANSION TANK (IF REQUIRED)

BUILDING
RETURN

Pipe sizing chart provides minimum pipe size for
com mon manifold piping and tank tappings to in -
sure  ad e quate  flow.

Number of Units     Common Manifold Size (Min)

1                                 2"

2                                  2"

3                                  2 1/2"

4                                  3"

5                                  3 1/2"

6                                  3 1/2"

Lower flows with soft water mean a higher
temperature rise.  A higher temperature rise may
cause nuisance tripping of a high limit or opening
of a relief valve when providing very hot water.  If
this presents a problem, increase the flow to the
temperature rise specified for 8 to 25 grains
hardness water.