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Circulator does not
operate
Check aquastat setting
PROBLEM
CAUSE
SOLUTION
Boiler does not
operate
Refer to boiler installation
instructions
Check main service switch
Check fused disconnect
Peak use of hot water
is greater than tank
storage capacity
Determine peak usage,
compare to tank capacity,
and add additional storage
(storage tank) if necessary
Improper aquastat
setting
Turn tank aquastat to safe
temperature setting
Electrical problem
(relay, wiring, etc.)
Check fuse and replace
Check circuit breaker and
reset (if applicable)
Check power supply
Aquastat set too low Raise aquastat setting to
safe level. See Section III
Undersized boiler with
no priority to
domestic hot water
Rewire for priority
No hot water at faucet
Water at faucet too
hot
Aquastat set too high Lower aquastat setting to
safe level
Tempering valve not
properly set or
defective
Check manufacturers
instructions
Scale build-up
If boiler, circulator, and tank
are operating satisfactorily,
coil may have scale coating.
See Section VI for tank
flushing procedure.
Check power supply
Replace as necessary
Faulty tank aquastat
Replace aquastat
Boiler cycles more
than 5 times per day
during hotest months
Excessive demand
Reduce demand or consider
larger tank
Faulty aquastat
Replace aquastat
Boiler high limit set
too low
Increase boiler high limit
setting
Insufficient hot water
Rust staining; bad
taste and odor in
water
Iron/minerals in water
supply
Filtration
Scale, hard white
particles from faucets,
popping sound from
tank
Lime, water hardness
above 7 grains-
120ppm
Water treatment; softener;
etc.
Rotten egg odor
Hydrogen Sulfide
Flush tank with chlorine
solution and install
alumninum anode rod(s)
Air from hot water
fixture
Electrolysis or air
introduced by water
supply
Properly ground heater &
replace anode rod(s). Check
well pump system.
Reduction in recovery Dip tube broken or
compromised by high
chlorine in water
Replace dip tube
Inlet/Outlet fitting
corrosion
Galvanic corrosion of
dissimilar metals
Install dielectric unions
T&P gushing water
Excessive water temp.
(above 210 °F)
Adjust or replace aquastat
and T&P valve
T&P Valve dripping
water
Excessive water
pressure (above 150
psi)
Check incoming water
supply pressure; closed loop
system (System Plus)
requires expansion tank
SECTION VI: TROUBLESHOOTING
