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Part number 550-100-325/0419
37
AquaBalance
®
Series 2 Wall Mount Gas-fired Water Boiler – Boiler Manual
Model
67
104
Figure 47
17 Install water piping
(continued)
Recirculation (if used)
Massachusetts code applications require
recirculation piping or heat-traced piping if the
distance from the water heater to the furthest
fixture exceeds 100 feet.
Maintaining domestic water
temperature in the supply piping
1. Recirculation is used to reduce wait time for water use, to
minimize hot water and energy waste caused during the waiting
period, and to prevent degradation of the system supply water
temperature. ASPE recommends recirculation when the distance
from the water heater to the furthest fixture exceeds 100 feet or
the time lag for hot water to reach a fixture(s) exceeds 30 seconds.
2. Consult local codes and American Society of Plumbing Engineers
(ASPE) Domestic Water Heating Design Manual - latest edition,
for further information.
Recirculation pump (Figure 48, page 38, item 9)
1. Little flow is required to maintain a temperature in the piping.
2. Size of circulator depends on minimum flow requirements of the
tempering valve.
3. Minimum flow rates of the tempering valve must be main-
tained.
Aquastat (Figure 48, page 38, item 10)
1. Used to control the on-off position of the circulator. Aquastat
is set 5° to 10° lower than mixed water outlet of the mixing
valve (item 7).
2. The circulator cannot run continuously as bypass through
the mixing valve will eventually allow the temperature on
the piping to climb to the water heater temperature during
draw periods.
Check valves (Figure 48, page 38, item 8)
1. Assure the flow of water in one direction.
2. Each check valve functions as follows:
a. prevent bypass in the event of pressure drop.
b. prevents thermal siphoning of hot water to the cold water
supply.
c. prevents flow of cold water to the tempered water supply.
A draw of tempered water will not result in flow of cold
water into the return loop.
Controls
1. Aquastat to enable domestic recirculation pump.
2. When using a recirculation set-up, it cannot be constant
circulation (never go to heating) and the Control Parameter
P14 change from 0 to 1.
Domestic water supplied to fixtures that could
pose an injury hazard due to high temperature,
such as showers and faucets, should be equipped
with a temperature regulating device, such as an
anti-scald mixing valve.
Expansion tank (Figure 48, page 38, item 11)
THERMAL EXPANSION TANK — If a backflow
preventer, check valve, or pressure reducing valve is
piped on cold water inlet of water heater, you must
install an expansion tank on cold water supply line
to prevent normal thermal expansion from
repeatedly forcing open T&P relief valve.
The T&P relief valve is not intended for constant
duty, such as relief of pressure due to repeated
normal system expansion. Refer to expansion
tank manufacturer’s instructions for proper siz-
ing.
Failure to comply could result in severe personal
injury, death or substantial property damage.
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