Filter
Top Products
AQUA PLUS indirect-fired water heaters — Product Manual
Recirculation
Massachusetts code applications require recircu-
lation 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 fix-
ture 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,
1998, for further information.
Time delay at fixtures
1. Figure 4, page 9 is from the ASPE Domestic Water Heating
Design Manual, 1998. It shows the time required for usable
hot water to arrive at a fixture based on the fixture flow rate
(available from industry and manufacturer’s data) and the
length and diameter of the dead-end branch pipe supplying
the fixture.
2. The time lag should generally not exceed 30 seconds.
3. For residential and office applications, the owner may prefer
a limit of 10 seconds.
4. You can use Figure 4 as a guide to determining the location
of circulation return lines relative to fixtures.
Balancing
1. When multiple branches are connected to the supply pip-
ing, each branch must be connected to the recirculation
system.
a. At each of these connections to the return piping, install
shutoff valves, a flow metering device, check valve and a
strainer as shown in Figure 5, page 9.
b. Check local codes for specific installation require-
ments.
2. These branches must be balanced to prevent pipe erosion
and unacceptable time delays at some fixtures.
3. Balancing options include circuit setters, memory stop valves
or factory preset devices (with flow metering provision in
the piping).
Components required
1. For residential applications, consult circulator manufacturer’s
data for circulator selection and additional components
required.
2. On most commercial systems, install the devices shown in
Figure 5, page 9, and any other devices or piping methods
required by local codes.
a. The check valves are required to prevent fixtures from
taking hot water through the return lines.
b. Shutoff valves are needed to allow cleaning and replacing
balancing devices.
c. Include strainers to remove sediment which could
damage the circulator and / or affect the flow balancing
devices.
3. Size the circulator and piping based on the temperature drop
allowed between the water available at the water heater and
the water delivered at the fixture.
a. The return piping will almost always be smaller than the
supply piping, but should never be smaller than ½” to
prevent problems with the circulator.
4. Make provision for removal of air in all return lines. Where
the returns cannot be vented by topmost fixtures in the
system, install automatic air venting at the top of the return
piping.
Connecting to the water heater
1. Install the domestic water components as shown in Fig-
ure 2, page 6.
2. See Figure 6, page 10 for the piping required to the water
heater.
— Continued on page 10 —
Part number GL-E223-ADOC 0311
8