John Wood Envirosense Power Vent - Manual (Page 12)

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Water supply systems may, because of such events as high line
pressure, frequent cut-offs, the effects of water hammer among others,
have installed devices such as pressure reducing valves, check valves,
back flow preventers, etc. to control these types of problems. When
these devices are not equipped with an internal by-pass, and no other
measures are taken, the devices cause the water system to be closed.
As water is heated, it expands (thermal expansion) and closed systems
do not allow for the expansion of heated water.
The water within the water heater tank expands as it is heated and
increases the pressure of the water system. If the relieving point of the
water heater’s temperature-pressure relief valve is reached, the valve will
relieve the excess pressure. the temperature-pressure relief valve
is not intended for the constant relief of thermal expansion. This is
an unacceptable condition and must be corrected.
It is recommended that any devices installed which could create a
closed system have a by-pass and/or the system have an expansion
tank to relieve the pressure built by thermal expansion in the water
system. Expansion tanks are available for ordering through a local
plumbing contractor. Contact the local water supplier and/or a service
agency for assistance in controlling these situations.
note: to protect against untimely corrosion of hot and cold
water fittings, it is strongly recommended that di-electric unions
or couplings be installed on this water heater when connected
to copper pipe.
All gas piping must comply with local codes and ordinances or with the
Natural Gas and Propane Installation Code (CAN/CSA B149.1) whichever
applies. Copper and brass tubing and fittings (except tin lined copper tubing)
should not be used.
fIGure 10.
CHEMICAL VAPOR CORROSION
CORROSION OF THE FLUEWAYS AND VENT SYSTEM MAY OCCUR IF
AIR FOR COMBUSTION CONTAINS CERTAIN CHEMICAL VAPORS. SUCH
CORROSION MAY RESULT IN FAILURE AND RISK OF ASPHYXIATION.
Spray can propellants, cleaning solvents, refrigerator and air
conditioning refrigerants, swimming pool chemicals, calcium and
sodium chloride (water softener salt), waxes, and process chemicals
are typical compounds which are potentially corrosive.
Do not store products of this sort near the heater. Also, air which is
brought in contact with the heater should not contain any of these
chemicals. If necessary, uncontaminated air should be obtained from
remote or outside sources. The limited warranty is voided when failure
of water heater is due to a corrosive atmosphere. (See limited warranty
for complete terms and conditions).
water pIpInG
HOTTER WATER CAN SCALD:
Water heaters are intended to produce hot water. Water heated to
a temperature which will satisfy space heating, clothes washing,
dish washing, cleaning and other sanitizing needs can scald and
permanently injure you upon contact. Some people are more likely
to be permanently injured by hot water than others. These include
the elderly, children, the infirm, or physically/mentally handicapped.
If anyone using hot water in your home fits into one of these groups
or if there is a local code or state law requiring a certain temperature
water at the hot water tap, then you must take special precautions. In
addition to using the lowest possible temperature setting that satisfies
your hot water needs, a means such as a *mixing valve should be used
at the hot water taps used by these people or at the water heater, see
Figure 2. Valves for reducing point of use temperature by mixing cold
and hot water are also available:
Consult a Qualified Installer or Service Agency. Follow manufacturer’s
instructions for installation of the valves. Before changing the factory setting on
the thermostat, read the “Temperature Regulation” section in this manual.
This water heater should not be connected to any heating systems or
component(s) used with a non-potable water heating appliance.
All piping components connected to this unit for space heating
applications should be suitable for use with potable water.
Toxic chemicals, such as those used for boiler treatment should not be
introduced into this system.
When the system requires water for space heating at temperatures
higher than required for domestic water purposes, a mixing valve must be
installed. Please refer to Figure 2 for suggested piping arrangement.
InstallInG the new water heater