Direct Connect System Piping - Single Boiler System; Verify The Application Will Work; Expansion Tank Location; Diaphragm- Or Bladder-Type Tank - Weil-McLain Evergreen EVG 70 Manual

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Direct Connect System Piping
Primary/secondary piping to boiler
Using primary/secondary piping will provide the most effi cient
and reliable operation of the boiler and the heating system.
1. Use information beginning on page 45 to size pump for
proper fl ow through the
2. Reference suggested piping layouts on pages 45 - 51 .
Some installations can be piped in numerous other ways
that will work equally as well as the suggestions here.

Verify the application will work:

For systems requiring a higher flow than that
recommended in Figure 44 − DO NOT use a
direct connect piping layout. Design system using
a primary/secondary piping layout using guidelines
starting on page 45 .
Systems zoning with circulators must use primary/
secondary piping layout using guidelines starting
on page 45 .
Check system fl ow rate
To determine whether direct connection will provide suitable
fl ow for the intended application, refer to Figure 44 .
1. The minimum temperature drop across the heat exchanger
is 20°F. Using fl ow rates higher than the maximum listed in
Figure 44 is NOT RECOMMENDED.
2. Design zoning to ensure minimum fl ow rate is maintained
under any call for heat condition that could see full input
rate (High Fire).
Systems using a modulating pump may operate
below the minimum fl ow rates listed in Figure 44
only if the boiler is operating at a reduced fi ring rate
(low fi re) when doing so. A pump that modulates
based on the system Delta T (¨T) would provide such
operation assurance by varying fl ow with fi ring rate.
Use a primary/secondary piping layout if the total fl ow through
the heat exchanger will be higher than the maximum listed in
Figure 44 .
Check system pipe design
Only systems with a single system pump zoned with zone valves
may use the direct connect system piping methods shown here.
Any system zoned with zone valves must include a
by-pass pressure regulator. Failure to comply may
reduce pump life.
Circulators
The boiler circulator (Taco 007e for Evergreen 70 and 110; Taco
0015e for Evergreen 155) is shipped loose. Locate it in the boiler
outlet, as shown in the appropriate piping diagram in this manual.
DO NOT use the boiler circulator in any location
other than the ones shown in this manual. The
boiler circulator is selected to ensure adequate fl ow
through the boiler.
Failure to comply could result in unreliable performance
and nuisance shut downs from insufficient flow.
Part number 550-100-191/0917
as-fired water boiler —
Evergreen ®
boiler.
Boiler Manual
70/110/155
-
Single Boiler System
If replacing included circulator with replacement
Taco 00e model, replace only with Taco Model
VR1816 circulator. Set VR1816 to match boiler
size below:
EVG 70:
EVG 110:
EVG 155:
You may use standard Taco 007 and 0015
circulators in place of respective 007e and 0015e
models.

Expansion tank location

Figure 45 and Figure 47 show typical installation of the system
expansion tank. It is highly recommended that you locate the air
separator and expansion tank as shown in the suggested piping
drawings on page 42 and page 43 .
Ensure that the expansion tank size will handle boiler and
system water volume and temperature. See tank manufacturer's
instructions and ratings for details. Additional tanks may be added
to the system if needed to handle the expansion. These tanks may
be installed by connecting to tees in the system piping.
Undersized expansion tanks cause system water to
be lost from the relief valve and makeup water to be
added through the fi ll valve. Eventual boiler failure
can result due to excessive make-up water addition.
Always locate the cold-water fi ll connection at the
expansion tank. Never locate this elsewhere.

Diaphragm- or bladder-type tank:

Refer to Figure 45 for suggested piping when using a diaphragm-
or bladder-type expansion tank.
Install an automatic air vent on top of the air separator, per
separator manufacturer's instructions.
Diaphragm- or bladder-type expansion tank—
Control fill pressure with the tank air charge
pressure. Always check pressure and charge tank
with tank removed from system to be sure reading
is accurate. Boiler relief valve is set for 30 PSIG.
Operating pressure of system, after temperature
expansion above cold fill pressure, should not
exceed 24 PSIG to avoid weeping of relief valve.
Figure 44 Maximum and minimum fl ow rates through
boiler heat exchanger
EVG MAXIMUM
Model
70 6.5 GPM
110 10.0 GPM
155 14.5 GPM
Constant Pressure 10
Constant Pressure 10
Max
MINIMUM
fl ow rate fl ow rate
through through
boiler boiler
3.0 GPM
5.0 GPM
7.0 GPM
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