Troubleshooting guide

Power VT
®
Plus WATER HEATER
31
PV500-44 12/13
14 TROUBLESHOOTING GUIDE
Problem Probable Cause Corrective Action
Starting or Pre-purge
Failure
Power Supply
Check fuse and/or circuit breaker. Check voltage at
120/24V step-down transformer.
On-Off Switch Check if On-Off switch is lighted.
Temperature Control
Check that the operating temperature control is set
higher than the temperature of the water heater.
Flame Safeguard Control
Check for bad ground or bad control. Replace if
necessary.
Remote enable/disable open
Enable water heater or place jumper between
terminals R1-R2.
Combustion Air blower
Check if fan connection terminals on flame control
is closed.
Check for 24V at field access terminal C2. Remote
interlock may be open.
Fan VFD may be defective. Verify proper voltage.
Air-proving Switch
Check switch contacts are closed.
Check for 24V at the N.O. side of air switch.
Check for 24V at the common side of air switch.
Check for proper blower pressure setting – adjust if
required. Air switch may be defective.
Blocked Filter Switch
(if equipped)
Check for 24V at the N.C. side of the blocked filter
switch. Replace filter or switch as required.
Flame Control Pressure Switch Check for 24V at the pressure switch terminal.
Loose Wire Connections Check connections to all components.
Flame Failure
Power Supply
Check fuse and/or circuit breaker. Check voltage at
120/24V step-down transformer.
Flame Safeguard Control
Check for bad ground or bad control. Replace if
necessary.
Hot Surface Igniter
Check resistance at room temperature and then the
amperage draw during heat-up. Replace if the
measured amperage is not within 3.5 to 5.0 Amps
or if measured resistance is not within 40-100 ohms
(at room temperature). Also, check for overheating
condition due to damaged refractory around igniter.
Air-proving Switch Check if switch is bouncing. Adjust or replace.
Gas Pressure
Check for proper inlet static and dynamic gas
pressure.
Combustion
Inadequate flame signal may result from improper
combustion. Adjust to proper CO2 levels at low fire.
Grounding
Check for proper ground from flame control to
burner housing.
Safety Limits
Check all safety limits for fault condition and correct
as required.