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Table 6 - Troubleshooting - *See scald warning below.
If draining of the water heater is necessary, open the T&P valve or
a hot water tap to prevent vacuum buildup in the tank and piping.
The risk of scald injury increases as you increase water temperature.
Use a water tempering or mixing valve and extreme caution when
using hot water to avoid scald injury. Consult codes for conformance.
Failure to follow the instructions in this warning statement could
result in serious personal injury or death from scalds.
Problem
Reason
Remedy
No Hot Water
Zone Valve Not Opening
Open manually or replace
Circulator Not Operating
Check or replace
Tank Control Set Too Low
Raise tank temperature*
Boiler Control Set Too Low
Raise boiler temperature
Wiring Incorrect
Check wiring
Tank Control Failure
Replace control
Zone Valve Failure
Replace Valve
Circulator Failure
Replace Circulator
Air Trap in Loop
Purge Air
Not Enough Hot
Water
Zone valve restriction
1” full bore replace zone valve
Circulator arrow reversed
Reverse circulator
Tank temperature too low
Raise tank temperature*
Boiler temperature too low
Raise boiler temperature
Boiler sized too small
Check sizing chart
Tank sized too small
Demand flow rate too high
Install mixing valve. Raise tank temperature
Air trap in loop
Purge air
Install flow regulator
Heat and tank come on together
Check wiring or set indirect as priority over heating
Draw tank down and lower thermostat. Recheck.
T&P Valve
Discharges
Tank Temperature Too High
Lower tank temperature
Water Expands When Heated
Install expansion tank
Water Pressure Too High
Install pressure reducing valve
Hot Tubs, Spas,
Multiple Showers,
High Demand
Pressure Too Low
Check line pressure for restriction
Tank recovery slow
Slow startup boiler. See chart
Not enough hot water
Boiler sized too small. See chart
Check flow rate. Compare to chart
Demand too great. Check flow rates and compare to chart. Install mixing
valve and/or flow restricting valve and raise tank and boiler temperature.*
