Pentair MiniMax Plus Service Manual page 31

Troubleshooting
When the pilot will not light or stay lit, there are five pos-
sible causes:
1. A weak or defective pilot generator.
2. A plugged or partially plugged pilot orifice.
3. A short in the control wiring.
4. A defective pilot safety in the gas valve.
5. Not enough gas.
NOTE
Before any testing is started; (1) Clean out the pilot
orifice. (2) Install a new pilot generator. (3) Clean
all wire connections and make sure they are
attached to the correct controls and terminals. (4)
Turn the gas on.
On the Honeywell Millivolt gas valve there are three
screw terminals located on top of the valve. One
terminal will be marked TH/PP. On this terminal, one
pilot generator wire and one wire from the control
wiring in attached. The other two terminals will be
marked T.H. and P.P. separately. The other pilot
generator wire should be attached to the terminal
marked P.P. The other heater control wire will be
attached to the remaining terminal marked T.H.
Attach your millivolt meter leads to the two pilot
generator terminals. Turn gas valve knob to "PILOT"
and push down. Light the pilot. If the millivolt meter
reading drops below zero, simply reverse your
millivolt meter leads. The meter should read at least
500 M.V. (millivolts) and in some instances, go as
high as 650 M.V. (pilot only). With a new generator
and clean pilot orifice installed, if you release the gas
valve knob and the pilot goes out, the gas valve is
defective.
Before you replace gas valve, disconnect the 2-TH
wires so that the gas valve won't be receiving any false
signals from any of the controls or wiring causing the
pilot flame to go out. Now, if the pilot won't stay lit,
replace the valve. If the pilot stays lit, with control
wires removed, there is a short in the wiring.
Rev. C 12-1-00
MINIMAX MILLIVOLT HEATER TESTING
PILOT WON'T LIGHT
PILOT LIT - BURNERS WON'T FIRE
Before This Test
1. Is the pump running and primed?
2. Is the filter clean? Are you sure?
3. Are all switches on?
4. Are the thermostats turned up?
5. Are there any valves that would prevent water
from reaching heater?
6. Clean main burner orifices.
Attach a jumper wire to the two TH terminals on the
gas valve. If the valve opens and the burners fire, the
gas valve is "OK". If the burners "do not" fire, gas
valve is defective.
This test bypasses all the other heater controls. So you
instantly know if the problem is in the gas valve or
the controls.
If the heater fires, remove the jumper wire from the
gas valve and attach it to each individual control to
find out which one is keeping the heater off.
3 1
P/N 38033