Weil-McLain PLUS LINE PLUS-E017-A/1206 - Manual (Page 23)

Part Number PLUS-E017-A/1206 2
Manual
• Installation • Start-Up • Usage • Maintenance • Parts
Figure 10 Recirculation connection at water heater
Figure 9
Recirculation components
Components
1 Circulator — Little flow is required to maintain a temperature in the piping. Size of
circulator depends on minimum flow requirements of the tempering valve. Minimum
flow rates of the tempering valve must be maintained.
2 Aquastat — 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 (#7). 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.
3 – 6 Check valves — Assure the flow of water in one direction. Each check valve func-
tions as follows: #3 and #4 prevent bypass in the event of pressure drop, #5 prevents
thermal siphoning of hot water to the cold water supply, #6 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.
Operation
• During period of normal use (fixtures on) — Circulator is off. There is no flow through
#6, there is flow through #5 equal to the flow at the fixtures, there is flow through #3
and/or #4 equal to flow at fixture.
• When all fixtures are off — Circulator is off. There is no flow through #3, #4, #5 or #6.
Water temperature in piping is cooling.
• When temperature at aquastat #2 falls 10° below temperature to be maintained
— Circulator is on. There is flow through #6 equal to the minimum required by the
mixing valve, flow through #3 and #4 equals the flow of the circulator. There is no flow
through #5.
• Aquastat reaches temperature — Circulator is off. There is no flow through #3, #4, #5
or #6.
Problems
• Missing check valves #3 or #4 — Extreme pressure drop can cause reverse flow of
water; hot to cold supply or cold to hot supply.
• Missing check valve #5 — Hot water can migrate from the water heater back through
the cold water supply.
• Missing check valve #6 — Cold water can be forced back through the tempered water
supply when a fixture is opened.
• No aquastat #2 — Pump runs continuously. Small amount of water will pass through
mixing valve. Eventually all hot water is flowing through valve. Recirculated water
through cold port, hot water through hot port.
• Circulator too small — Mixing valve performance erratic.