Primera 400B Installation & Maintenance Manual page 25

Circulator (confirm proper sizing)
Full Port Isolation Ball Valve
Swing Check Valve
Union
Pressure relief valve. Pipe to drain with
no restrictions or valves.
Return
PRIMERA
temperature 3
to the boiler
must be = 130°F
Low
Temperature
Bypass
with Valve.
(see note 3)
Minimum static pressure of 15 psi required
in the primary boiler loop at all times.
Piping Schematic for Multiple PRIMERA® Boilers - Primary-Secondary
When low temperature bypass is used,
boiler flow rate is adjusted using the
valve upstream of the bypass.
PRIMERA
2
Notes:
1. Piping shared by multiple PRIMERA boilers, must be sized for the total anticipated flow at
a maximum of velocity recommended for the piping material used.
2. Pump sizing must be confirmed for the required boiler flow rate (gpm) against the head loss
of the boiler and the boiler piping circuit to and from the building loop connection point.
3. Low temperature bypass from hot outlet of boiler to cold inlet is required if return water to
the boiler is expected to drop below 130°F. A thermostatic mixing valve (part no.104348)
is recommended if the bypass is installed. Pipe diameter of bypass is 2 inch.
A multiple boiler lead-lag control is recommended on all multiple boiler installations. If
4.
multiple boiler control is not used, operating probe from each boiler must be relocated to
the indicated loop sensor location after initial boiler delta T and flow rate setup.
5. Refer to individual boiler installation manuals for more details.
PRIMERA
1
Multiple
Loop Sensor
Boiler
Control
25
Air Separator
Exp.
Tank
Makeup Line
Primary-secondary piping interface.
Maximum of 4 pipe diameters
B
from point A to B is recommended.
IMPORTANT:
A
Flow through the building loop must always be
125% of the flow required by all boilers firing at
any given time. Special attention to boiler
sequencing is required if VFD is used on the
building loop.
Building Return
Building Supply
Continuous flow is
required. Use a
continuous loop or
employ 3-way valves
adequate to maintain
minimum flow
34-50 04/02/2010