Part number 550-142-085/0712
WM97+
gas
-
fired
water
boiler
—
Boiler Manual
– 42 –
Figure 46
WM97+70/110
Zone valve zoning — direct
connection (boiler circulator provides flow
for system — boiler primary/secondary
by-pass valve CLOSED) (See next page
for legend)
The WM97+70 or 110 boiler internal circulator can be used to circulate
many heating systems using the arrangement shown in Figure 46 and
in Figure 47, page 43.
Verify the application will work:
To determine if direct connection will provide enough flow for the system, use
Figure 48, page 43. Pay careful attention to the following .
•
MAIN LINE SIZING
— Use at least the size shown for mains.
•
BRANCH LINES
— Branch lines must be at least ¾ inch, as shown.
•
TOTAL FLOW
— This is the total flow to the system at a 20°F tempera-
ture drop.
•
CIRCULATOR HEAD AVAILABLE
— This is the head available to
overcome head loss through the piping. (This equals circulator capacity
minus boiler internal flow losses.)
INFORMATION APPLICABLE ONLY TO BASEBOARD SYSTEMS:
•
MINIMUM NUMBER OF CIRCUITS
— The system must be split
into no less than this number of circuits — to limit the flow to either the
maximum for ¾” piping or the maximum the circulator can handle with
its available head.
•
MAXIMUM FLOW PER CIRCUIT
— This is the highest flow acceptable
for any one circuit. If a circuit requires higher flow, split the circuit into
multiple circuits that all have flow within the limit. If this cannot be done,
the circuit must be piped as primary/secondary per Figure 49, page 44.
•
MAXIMUM LOAD OF ANY CIRCUIT
— This is determined from the
maximum flow for any circuit (BTUH = GPM x 500 x 20°F).
•
MAXIMUM FEET BASEBOARD
— This is determined from the maxi-
mum load, assuming baseboard output of 600 Btuh per foot).
•
MAXIMUM CIRCUIT LENGTH
— This is the maximum total length of
any circuit, measured along the piping, beginning at the boiler, along the
main line, through the heating branch and back to the boiler. DO NOT
use direct connection if any heating loop exceeds this value.
For systems other than finned tube or cast iron
baseboard —
Use the CIRCULATOR HEAD AVAILABLE to
determine whether the boiler circulator can provide the flow
needed. (See Figure 48, page 43.)
For systems requiring higher flow or head loss —
apply the suggested piping of Figure 49, page 44, NOT that of
Figure 46.
Balancing, if required
— Substitute a memory-stop valve
for one of the isolation valves in each zone to use the memory-
stop valve for balancing flow as well as isolation.
DHW tank as a zone
—
A DHW tank can be connected
in the system as a zone if NOT direct-connecting the boiler to
a DHW tank or CWH. If domestic priority is required, use a
Weil-WMZV zone controller to operate zones and activate the
boiler.
System piping
Wire all zone valve end switches to the
boiler’s ZONE 2 input. Provide isolation
relays if using 3-wire zone valves.
CWH unit installations
— refer to the
Weil-McLain CWH manual for piping and
installation requirements.
By-pass pressure regulator
— All zone
valve systems shown in this manual REC-
OMMEND the installation of a by-pass
pressure regulator (unless other provision
is made). This is common practice for
zone valve systems, but is mandatory for
the WM97+ applications. This is because
the WM97+ control can be set to continue
running the circulator after the call for heat
has ended (called post-pump). The by-pass
pressure regulator prevents dead-heading
the circulator if all zone valves are closed.
DHW refers to an indirect-fired domestic hot
water storage tank. CWH refers to a Weil-
McLain Companion Water Heater.
ZONE VALVE zoning — direct connection
Internal P/S by-pass valve CLOSED
WM97+70 or 110 only
Содержание WM97+110
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