Weil-McLain WM97+70 Specifications download pdf (Page 44)

Part number 550-142-120/0113

WM97+ gas-fired water boiler — Boiler Manual

– 44 –

Figure 50 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 50 and

in Figure 51, page 45.

Verify the application will work:

To determine if direct connection will provide enough ﬂow for the system, use

Figure 52, page 45. 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 53, page 46.

• 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 52, page 45.)

For systems requiring higher ﬂow or head loss —

apply the suggested piping of Figure 53, page 46, NOT that of

Figure 50.

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

1 2 ... 39 40 41 42 43 44 45 46 47 48 49 ... 135 136

Comments to this Manuals

No comments

Weil-McLain WM97+70 Specifications Page 44

Comments to this Manuals

Related products and manuals for Water heaters & boilers Weil-McLain WM97+70