34-50 04/02/2010
29
Piping Schematic for Two PRIMERA® Water Heaters and Two Storage Tanks
Notes:
1. All piping to the storage tanks
must be balanced; this include cold inlet, hot outlet to
the building and the piping to and from the water heater main headers.
2. Piping shared by multiple PRIMERA heaters, must be sized for the total anticipated
flow of approximately 6 feet per second as required for type L copper.
3. Pump sizing must be confirmed for the required heater flow rate (gpm) against the
head loss of the water heater-to-tank piping, as well as the water heater itself.
4. Low temperature bypass from hot outlet to the cold inlet is required on each heater.
5. Operating probes are moved to storage tank after water heater flow rate setup.
3/4" fitting required and multiple-probe thermowell (part no. 102561).
6. Pipe all temperature and pressure relief valves to drain with no restrictions or valves.
7. Refer to heater installation manual (form 34-50) for more details.
Circulator (confirm proper sizing)
Full Port Isolation Ball Valve
Swing Check Valve
Union
Temperature and Pressure Relief Valve
Storage
Tank 1
Storage
Tank 2
PRIMERA
1
PRIMERA
2
Exp.
Tank
Hot Outlet
Cold Inlet
Building Return
Models Total GPM Min. Pipe Size
400W / 540W 60 2" dia.
750W 122 3" dia.
1000W 152 3.5" dia.
1200W 92 2.5" dia.
1600W 122 3" dia.
2000W 152 3.5" dia.
Main Header Sizing for Two Heaters
Operating Probes
Low Temperature
Bypass with Valve.
Size bypass piping and
valve for 2 inches
2.5" dia. for
models 1000W
and 2000W.
All other
models 2" dia.
Return temperature
to the water heater
must be = 130°F
Use the outlet
piping isolation
valve to set
water he at e r ΔT
and flow rate.
NOTE: Pipe size from this T
to each storage tank can be
reduced from the main header
size, but doing so limits the
number of heaters that can
operate if one of the tanks is
valved off for maintenance.
Size pipe for a velocity of 6
feet per second at the antici-
pated flow rate.
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