Install water piping
Use two wrenches when tightening water piping
at boiler, using one of the wrenches to prevent
the boiler interior piping from turning. Failure to
support the boiler piping connections to prevent
them from turning could cause damage to boiler
components.
General piping information
Use piping unions near boiler
Install piping unions near boiler outlet and return
to facilitate future service requiring heat exchanger
removal.
Additional controls, if required
The control uses temperature sensors to provide both
high limit protection and modulating temperature
control.
The control’s high limit function requires
manual reset
. Some codes/jurisdictions may
require additional external controls for high limit
and/or low water cutoff protection.
Additional limit controls
Following standard industry practices, if installation is to comply
with ASME or Canadian requirements, an additional high
temperature limit may be needed. Consult local requirements for
other codes/standards to determine if needed.
1. Install a manual reset high temperature limit constructed to
prevent a temperature setting above 200°F in system supply
piping between boiler and isolation valve. (Note that the
control operating limit function shuts the boiler down at
195°F, or lower if set to a lower value.)
Multi-temperature systems
— If the heating
system includes circuits that require lower
temperature water (radiant slab circuits, for
example) as well as higher temperature circuits, it is
recommended to protect low-temperature circuits
with limit controls that are wired to the control
external limit circuit terminals.
Low temperature materials — If using temperature-
limited materials (such as PEX tubing) in system
piping, it is recommended to protect the system
with limit controls that are wired to the controls
external limit circuit.
2. See instructions beginning on page 60 for wiring information.
3. If using a manual reset limit control or wiring in the manual
reset circuit, set
ECO
control boiler limit at least 20°F less
than the external manual reset limit (i.e., set
ECO
control no
higher than 180°F for a 200°F external limit, for example).
Separate low water cutoff
1. A separate low water cutoff device is recommended when the
boiler is installed above piping level, and may be required by
certain state or local codes or insurance companies. Consult
local requirements to determine. See the NOTICE above
regarding the inherent protection provided by the Control
module.
2. The Control’s integral protection is accepted in many
jurisdictions as meeting the requirement for low water
protection. See page 63 for details.
3. When required, use a low water cutoff designed for water
installations. Electrode probe-type is recommended.
See Replacement parts section at the end of this manual for
the Weil-McLain low water cut-off kit.
4. Purchase low water cutoff and install in a tee in the supply
piping above boiler.
5. See field wiring instructions beginning on page 60 for wiring
additional limit controls.
Back flow preventer
1. Use back flow preventer in the cold water supply piping if
required by local codes.
System/zone pipe sizing
(Baseboard, convectors or cast iron radiators ONLY)
1. For residential space heating applications (other than
radiant heating or unit heaters) ONLY, you can use the sizing
suggestions in Figure 46.
Figure 46
Suggested pipe sizing for system headers and
zone piping — RESIDENTIAL with baseboard,
convectors or cast iron radiators ONLY (20°F
temperature rise)
ECO
Model
System header
70/110
1" or larger
155
1¼" or larger
Recommendations are based on a 20°F temperature drop
through the system.
Suggested maximum load per zone
Copper pipe and
baseboard size
Maximum recommended
feet of baseboard
¾"
67
1"
104
Size zone circulators to handle the required flow and head
loss for each zone.
System water piping methods
Direct connection piping to boiler
It is recommended, but not required, to use primary/
secondary piping to the boiler. Using primary/
secondary piping will provide the most efficient
and reliable operation of the boiler and the heating
system.
Installations using direct connection piping layout
should:
1. Read the NOTICES and guidelines beginning on to determine
if the system is eligible for this piping strategy.
2. If eligible, reference suggested piping layouts on pages 46
and 47.
3. Use primary/secondary piping if system ineligible.
Part number 550-142-190/1218
42
®
S
ERIES
2
G
AS
-
FIRED
WATER
BOILER
—
Boiler Manual
