Hubbell Electric Heater Company V15 - Manual (Page 20)

20
Faulty thermostat. Check thermostat adjustment.
Monitor thermostat as described
in Section III, Quarterly
Inspection. Replace if necessary.
Heating element not working on all
phases Check to see that heating
element is working on all
phases, by checking the
resistance (ohms) value for each
element and comparing with the
chart included in Section VI.
Blown fuse in element fuse block,
if installed. Replace fuse.
Water temperature below
settings at all times
Heater improperly sized Verify heater is properly sized
for the flow rate and temperature
rise of your system. See formulas
included in Section VI. Replace
elements with proper size as
necessary.
Relief valve discharges
continuously Excessive temperature or pressure
in tank Temperature and pressure relief
valves are made to operate if the
water temperature exceeds
210
°F or water pressure exceeds
the pressure rating of the safety
relief valve. If trouble is
excessive temperature, then
thermostat is not shutting off at
the right setting and thermostat
must be replaced.