Install Instructions
21
A. Design and install boiler and system piping to
prevent oxygen contamination of boiler water and
frequent water additions.
1. There are many possible causes of oxygen
contamination such as:
a. Addition of excessive make-up water as a result
of system leaks.
b. Absorption through open tanks and ttings.
c. Oxygen permeable materials in the distribution
system.
2. In order to insure long product life, oxygen sources
must be eliminated. This can be accomplished by
taking the following measures:
a. Repairing system leaks to eliminate the need for
addition of make-up water.
b. Eliminating open tanks from the system.
c. Eliminating and/or repairing ttings which allow
oxygen absorption.
d. Use of non-permeable materials in the
distribution system.
e. Isolating the boiler from the system water by
installing a heat exchanger.
f. Use properly designed and operating air
elimination devices in water piping.
IV. WATER PIPING AND TRIM
B. Optional Probe LWCO Installation
WARNING
DO NOT ATTEMPT to cut factory wires to
install an aftermarket Low Water Cut Off
In all cases, follow the Low Water Cut Off
(LWCO) manufacturer’s instructions.
WARNING
Failure to properly pipe boiler may result in improper operation and damage to boiler or structure.
Oxygen contamination of boiler water will cause corrosion of iron and steel boiler components, and
can lead to boiler failure. U.S. Boiler’s Standard Warranty does not cover problems caused by oxygen
1. A low water cutoff is required to protect
a gas-red hot water boiler when any
connected heat distributor (radiation) is
installed below the top of the hot water
boiler (i.e. baseboard on the same oor
level as the boiler). In addition, some
jurisdictions require the use of a LWCO
with a hot water boiler as a redundant safety
control.
It is recommended that the LWCO control
is installed above the boiler to provide
the highest level of protection. However,
where the LWCO control is approved by the
LWCO control manufacturer for installation
in a high boiler tapping of a water boiler, the
use of the listed LWCO control is permitted
when it is installed according to the LWCO
manufacturer’s instructions.
2. The recommended location for a LWCO on
gas hot water boilers is above the boiler, in
the supply piping. The minimum safe water
level of a water boiler is at the uppermost
top of the boiler; that is, it must be full of
water to operate safely.
3. Typically, in residential applications, a probe
type LWCO is used instead of a oat type,
due to their relative costs and the simplicity
of piping for a probe LWCO.
4. Piping and ttings required to install LWCO
are eld supplied.
Figure 10: Recommended Probe LWCO Location