Instruction manual
Page 14
C
irculator does not 
operate
Check aquastat setting
PROBLEM CAUSE SOLUTION
Boiler does not 
operate
Refer to boiler installation 
instructions
Check main service switch
C
heck 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
T
empering valve not 
properly set or 
defective
C
heck manufacturers 
instructions
S
cale 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
R
eplace 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










