Troubleshooting guide

Power VT
®
Plus WATER HEATER
21
PV500-44 12/13
9 OPERATING AND SAFETY CONTROLS
WARNING: Turn off all electrical service to the appliance when accessing the limit or other controls located
inside the control cabinet. This cabinet contains High Voltage wiring and terminals. If the electrical service is
not turned off and these terminals are touched, a dangerous shock causing personal injury or loss of life
could occur. Close and fasten the control cabinet cover before restoring electrical service to the appliance.
9.1 Temperature and Pressure Relief Valve(s)
A Temperature and Pressure Relief Valve(s) sized in accordance with the ASME Boiler and Pressure Vessel Code is
installed in the tank.
WARNING: Secure the relief valve pipe to a suitable floor drain such that very hot water does not openly
splash during a significant relief valve discharge. If the relief valve pipe is not routed and secured to a
suitable drain, hot water discharge can result in property damage, scalding and personal injury or loss of
life.
 The drain pipe may not be smaller than the relief valve opening and must be secured to prevent it from lifting out
of the drain under discharge pressure.
 CAUTION: Do not install a reducing coupling, valve or other restriction in the T&P relief valve(s)
discharge line. The discharge line shall allow complete drainage of the valve and line. Relief valves should be
manually operated at least once a year.
 Thermal Expansion - A relief valve that periodically discharges may result from thermal expansion, if the water
heater is installed in a system closed by components, such as a backflow preventer or check valve in the cold
water supply. These systems must be provided with means to control expansion. Contact a water heater or
plumbing professional to resolve this situation.
 CAUTION: Do not plug the relief valve, as this will eliminate the critical water temperature and pressure
protection it provides.
9.2 Operating Temperature Control
An adjustable digital operating control is located in the front control panel. The control is factory pre-set at
approximately 120
º
F. To adjust the setpoint to deliver the desired water temperature, press and release the Set 1 key
on the face of the control. When setpoint adjustment is enabled, use the arrow keys to adjust the set point to the
desired system temperature. See TempTrac Electronic Controller Panel in this manual for more information.

9.3 High Water Temperature Limit Control
Appliances are equipped with adjustable limit and high limit controls to control the maximum discharge water
temperature. These controls are located inside the control cabinet and are accessed by removing the bottom cover.
The high limit control is optionally available as the manual reset type and may be reset by pressing the limit reset
button accessible through the control panel cover. Pressing the reset on the High Limit Control will not cause the
control to reset until the water temperature has dropped below the set point of the manual reset High Limit Control.
The Lower Limit is of the auto reset type and can be dial adjusted to operate just above the set point of the main
Operating Temperature Control.
9.4 Cathodic Protection
PVI water heaters do not utilize cathodic protection. However, in hot water systems utilizing cathodic protection,
hydrogen gas can be produced when the hot water system has not been used for a long period of time (generally
two weeks or more). Hydrogen gas is extremely flammable. To prevent the possibility of injury under these
conditions, one of the hot water system faucets should be opened for several minutes before using any electrical
device connected to the hot water system. If hydrogen is present, there will be an unusual sound such as air
escaping through the pipe as the hot water begins to flow. Do not smoke, have open flames or turn electrical
switches on or off near the faucet at the time it is open.
9.5 Electronic Low Water Cut-Off (Optional)
When the water level is above the electrode position in the tank, the reset pushbutton will energize the control (LED
will be lit). The control remains energized until the water level recedes below the electrode position (LED will not be
lit). Unless otherwise specified, there is a three-second time delay on decreasing level. Water level must be below
tank probe location for full three seconds before control de-energizes.