Lochinvar CP-5M-4/08, 45 Water Chemistry, Softened Water Systems, Table - Q, Pump Operation

NOTE:

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.

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.

WATER CHEMISTRY

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.

SOFTENED WATER SYSTEMS

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

COLD WATER SUPPLY

HOT WATER SUPPLY

EXPANSION TANK (IF REQUIRED)

RELIEF

VALVE

CIRCULATING PUMP

RELIEF

LOCK-TEMPVALVE

STORAGE

TANK

DRAIN

BUILDING

RETURN

FIG. 49 Typical Water Heater Piping with Storage Tank

TABLE - Q

COMMON WATER MANIFOLD SIZE FOR MULTIPLE HOT WATER SUPPLY BOILER INSTALLATIONS

Pipe sizing chart provides minimum pipe size for common manifold piping and tank tappings to in- sure adequate 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"

PUMP OPERATION

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

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