
lp-770 Rev. 000 Rel. 000 Date 6.21.21
17
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*
Boiler control set too low
Raise boiler 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 ther-
mostat. 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.*
Hot Water Has Rotten Egg Odor
Problem
Possible Solution
Supply water has high sulfate or
mineral content
Check with water quality
specialist in your area. Have
water supply analyzed.
Address water quality issues
according to specialist’s
recommendations.
Table 14 - 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.