Mighty Therm Lo-Nox
Page 13
to the heat exchanger. Specifications in Table 4
include allowance for 30 feet of piping and 6
elbows between heater and tank.
IMPORTANT: Check oil level in pump before
starting. Oil pump every three (3) months. Fill
bearing assembly to lower level of overflow
vent. Add five (5) or six (6) drops of oil to front
and rear of motor. Use 20W non-detergent oil.
Pumps located in excessively hot or dusty
locations should be oiled once a month. Self
lubricating pumps do not require oiling.
4.
The pump should be accessible for lubrication,
inspection and service.
3.3.5 Water Pressure
It is very important that water pressure in the
system be maintained above 30 psi. If the system
pressure should drop below this, the vapor pressure of
water in the suction side of the pump can cause
hammer and cavitation in the pump and damage the
heater through lack of water circulation.
For protection against excessive pressure the
water heater is equipped with a pressure relief valve.
When the water heater is connected to a separate
storage vessel, a temperature and pressure relief valve
must be installed on the storage vessel. The
temperature and pressure relief valve must be design-
Figure 14. Hot Water Supply System Using Dual Tanks.
NOTES:
1. Heavy line
indicates Heater to Tank Circulating Loop.
2. When a very large volume of water is circulated in the building
loop with the use of a separate pump, tee building loop into cold
water supply and return to storage tank.
Flow Head* Temp. Rise
Water Rate Loss Across
Model Category (GPM) (ft.) Heater, (°F)
Soft
45
5.0
17
500
Normal
68
9.9
11
Hard
90
15.7
8
Soft
45
5.3
24
715
Normal
68
11.0
16
Hard
90
17.8
12
Soft
45
3.9
35
1010
Normal
68
7.5
23
Hard
90
11.7
18
Soft**
68
8.1
32
1430
Normal
68
8.1
32
Hard
90
12.6
24
Soft**
90
13.5
30
1825
Normal**
90
13.5
30
Hard
90
13.5
30
Water Category Grain Hardness per Gal.
Soft
1 through 7.5
Normal 7.6 through 17
Hard
Over 17
* Pressure drop includes loss through 30 feet of pipe and normal fittings when
heater is installed with storage tank. Pipe and fittings are assumed to be 2" on
Models (500-715) and 2 1/2" on Models (1010-1825)
** To prevent erosion, these models must be ordered with cupro-nickel heat
exchanger tubes.
Table 4. Pump Performance Requirements.
