GBT A2-035, Инструкция по установке и эксплуатации

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Page 11
When the system requires water for space heating at temperatures higher than 140
o
F (60
o
C), use a mixing
valve or similar means to reduce the potable water supply temperature to avoid scald injuries. The operating
thermostat should be set at the lowest possible temperature that provides useful service for the application. For
potable water uses, 120 – 125
o
F (49 – 51
o
C) is recommended (use a tank mounted Operating Aquastat).
This heater/boiler requires forced water circulation when the burner is operating. Pump selection and sizing
depends upon the type of system in which the heater/boiler will be used. Pressure loss through the A2000 heat
exchanger is provided below.
The maximum flow rate through the A2000 heat exchanger is 56 gpm due to
velocity induced tube erosion.
The A2000 models are designed to operate with a return water temperature of 120
o
F (49
o
C) or greater.
Condensation of the flue gasses may result if the inlet water temperature is under 120° F. This appliance and
the venting connected to it are not designed to withstand repeated condensation. Low operating temperatures
and frequent cold start-ups must be prevented. Frequent operation below 120°F return water temperature will
damage the heat exchanger and
void the warranty . If low operating temperatures cannot be avoided, a
feedback loop (by-pass) must be installed as shown in the DIAGRAMS section.
Do not operate your A2000 heater/boiler with inlet water temperatures lower than
120
o
F (49
o
C). Consistent operation below these temperatures will cause heat
exchanger corrosion and void the warranty. A By-Pass piping arrangement is
required when inlet water temperatures are consistently below 120
o
F.
Water temperature thermometers should be obtained and field installed as shown in the DIAGRAMS section.
Water Chemistry:
Water that is very soft, very hard, having a high total dissolved solids (TDS), or an acidic or
alkaline pH will shorten the life of the heat exchanger. The water should be between 5 and 15 grains per gallon
hardness. Water with a hardness exceeding 15 grains or a TDS exceeding 2500 ppm should be softened or
treated to prevent scaling of the heat exchanger, which reduces efficiency and ultimately may cause premature
failure of the heat exchanger due to overheating. Water softer than 5 grains may be corrosive, causing
premature heat exchanger failure, and must be treated with a suitable buffer. The ideal pH for water used in a
storage tank or copper heating system is 7.2 to 7.8. Corrosion of the heat exchanger may result when the pH is
lower than 6 or higher than 8.
Scaling of the heat exchanger is aggravated with low water flow rates and high water temperatures. To
minimize scaling, use the highest water flow rate and lowest water temperature set-point suitable for the
application.
FAILURE TO PROPERLY OBSERVE THE ABOVE WATER CHEMISTRY
RECOMMENDATIONS WILL VOID THE WARRANTY AND MAY RESULT IN A VERY
SHORT LIFE OF YOUR BOILER/HEATER.
Leak Testing: The A2000 heater/boiler does not require hydrostatic pressure testing, as the heat exchanger
was factory tested for 160 psig operating pressure. However, the water piping connections to the heater, and
the balance of the water system should be leak tested prior to putting the system into operation. Leaks must be
immediately repaired to prevent damage to the heater or property.
Flow
(gpm) A2-035 A2-050 A2-070 A2-097 A2-120 A2-140
10
1.5 2.0 2.5 4.5 4.5 4.5
20 4 6 8 12 12 12
30 9 13 15 21 21 21
40 17 22.5 26 35 35 35
50 36 46 52 52 52
56 57 64 64 64
Head Loss (ft hd) Vs. Water Flow Rate Through Heat Exchanger (Approximate)
A2000 Model
psi = (ft hd) x 0.434