Primary/Secondary System Piping - Single Boiler System; Expansion Tank Location; Diaphragm- Or Bladder-Type Tank; Closed-Type Expansion Tank - Weil-McLain Eco Tec 2 Series Manual

ECO ® Tec series 2 gas-fired water boiler – boiler manual
Primary/Secondary System Piping -

Expansion tank location

Figure 60 and Figure 61 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 pages 54-56.
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 fill valve. Eventual boiler
failure can result due to excessive make-up
water addition. Always locate the cold-
water fill connection at the expansion
tank. Never locate this elsewhere.

Diaphragm- or bladder-type tank:

Refer to Figure 60 for suggested piping when using a
diaphragm- or bladder-type expansion tank.
Diaphragm- or bladder-type expansion
tank—Calculated cold fill pressure
should equal 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.
Install an automatic air vent on top of the air separator,
per separator manufacturer's instructions.
Part number 550-100-270/0122
Figure 60 Piping to diaphragm (or bladder) expansion tank

Closed-type expansion tank

DO NOT use a closed-type tank if connecting to a water
heater that is equipped with an automatic air vent or if an
automatic air vent is incorporated into the system piping.
Figure 61, page 52 shows suggested piping when using a closed-type
expansion tank, in which the air is directly in contact with tank water.
Connect piping (½" or ¾") from the air separator outlet to the tank fitting.
Slope any horizontal piping a minimum of 1 inch per 5 feet of horizontal pipe.
Always use a tank fitting such as the B&G Tank-trol or Taco Taco-trol.
The fitting reduces gravity flow of water in the piping to the tank, avoids
air bubbling through the tank water, and provides the proper fill height in
the tank. Continued on next page.
Single Boiler System
51