Pipe Size Requirements; Circulating Pump - Lochinvar 399 Installation And Service Manual

potable water exceeding these specifications. Heating of high
hardness and/or high total dissolved solids water will 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. Water with a
hardness of less than 5 grains per gallon will usually have a
low 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.
COLD WATER
SUPPLY
MIXING VALVE
HOT WATER
SUPPLY
RELIEF
VALVE
LOCK-TEMP
STORAGE
TANK
DRAIN
FIG. 54 Typical Water Heater Piping with Storage Tank

Pipe Size Requirements

The pipe sizing chart provides minimum pipe size for common
manifold piping to ensure adequate flow.
EXPANSION TANK
(IF REQUIRED)
CIRCULATING
PUMP
RELIEF
VALVE
BUILDING
RETURN
Installation and
Service Manual
Number of Units
399,999 - 750,000 Btu/hr Models
1
2
3
4
5
6
Number of Units
990,000 - 2,070,000 Btu/hr Models
1
2
3
4
5
6

Circulating Pump

1. The water heater 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 pump correctly. See
on page 52.
3. The water heater is equipped with a factory-supplied pump
delay system in accordance with the requirements of the
latest edition of ASHRAE 90.1.
4. Lubricate pump to manufacturers recommendations. Pump
damage due to inadequate lubrication is non-warrantable.
5. Standard water heaters are furnished with the following
circulating pump. Mount pump on unit's inlet water
connection.
399,999 - 750,000 Btu/hr Models
1/4 HP , 120 VAC, 5.8 Amp
990,000 - 2,070,000 Btu/hr Models
1/2 HP , 120 VAC, 7.4 Amp
53
TABLE-X
Common Manifold
Size (Min.)
2"
3"
3 1/2"
4"
5"
5"
Common Manifold
Size (Min.)
2 1/2"
4"
4"
5"
6"
6"