lp-181 Rev. 3.3.15
9
Troubleshooting
No Hot Water
Not Enough Hot Water
Problem
Possible Solution
Problem
Possible Solution
Zone valve not opening
Open manually to replace
Zone valve restriction
1” full bore replace zone valve
Circulator not operating
Check or replace
Circulator arrow reversed
Reverse circulator
Tank control set too low
Raise tank temperature*
Tank temperature too low
Raise tank temperature*
Control set too low
Raise control temperature
Boiler temperature too low
Raise boiler temperature
Wiring incorrect
Check wiring
Boiler sized too small
Check sizing chart
Tank control failure
Replace control
Tank sized too small
Check sizing chart
Zone valve failure
Replace valve
Demand flow rate too high
Install mixing valve. Raise tank
temperature
Circulator failure
Replace circulator
Air trap in loop
Purge air
Install flow regulator
Air trap in loop
Purge air
Heat and tank come on
together
Check wiring or set indirect as
priority over heating
Draw tank down and lower
thermostat. Recheck.
Not enough space heat
Boiler sized too small.
Consult chart.
Slow recovery
Circulator head capacity too
low
T&P Valve Discharges
Hot Tubs, Spas, Multiple Showers, High Demand
Problem
Possible Solution
Problem
Possible Solution
Tank temperature too high
Lower tank temperature
Pressure too low
Check line pressure for
restriction
Water expands when heated
Install expansion tank
Tank recovery slow
Slow startup boiler. See chart
Water pressure too high
Install pressure reducing
valve
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.*
Table 3 - Troubleshooting - *See scald warning below.
If draining of the storage tank 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.
