FloAire FAV-M - Manual (Page 38)

38
Maxitrol Series 44 Troubleshooting
Symptom Possible Cause Field Test Remedy
No gas flow Modulating valve installed
improperly Arrow in side of valve should
point in direction of gas flow. Install properly
Continuous low fire
(electronics problem) No voltage to amplifier
Short in modulator coil circuit
Short in TS144 circuit
Defective amplifier Check for 24-v ac at amplifier
terminals 8 and 9
Remove wires connected to
amplifier terminals 6 and 7;
measure resistance
MR212: 60 – 80 ohms
M611 & M511: 45 to 55 ohms
Remove wires connected to
amplifier terminals 1, 2, and
3. Measure resistance across
wires 1 and 3, then across 2
and 3. Meter should read
greater than 2500 ohms.
Follow procedures in the
preliminary circuit analysis
section Provide 24-v ac to
amplifier
If proper resistance
values are not observed;
replace modulator head
or repair wiring.
If readings are incorrect,
replace the TS114 or
repair wiring.
After following the
preliminary circuit
analysis test without
satisfactory results, the
amplifier can be
assumed defective.
Install replacement.
Continuous low fire
(electronics OK) Open in modulator coil circuit
Plunger missing, jammed or
improperly installed
Remove wires connected to
amplifier terminals 6 and 7
measure resistance
MR212: 60 – 80 ohms
M611 & M511: 45 to 55 ohms
Inspect: plunger should
operate freely in solenoid
sleeve. If proper resistance
values are not observed,
replace modulator head
or repair wiring
Clean or replace plunger
if necessary
Incorrect minimum fire Incorrect by-pass metering
valve adjustment
Excessive negative burner
pressure Re-set low fire (see start-up
instructions)
Close main-gas supply and
measure manifold pressure
with blower opening. Reading
should be less than 1.5-in wc
negative pressure. Adjust to proper low fire
If reading is greater than
1.5-in wc negative
pressure, check for
clogged filters or other
inlet air restrictions.
Continuous minimum
discharge temperature Defective amplifier
Short in T244 or TS244/TD244
circuit
Refer to the preliminary circuit
analysis section
Remove wires to amplifier
terminals 4 and 5. Set T244
or TD244 to maximum setting.
Measure resistance across
wires. Meter should read
6000 ohms +- 1000 ohms. If
TS244/TD244 are used, meter
should read 4500 ohms +-
1000 (TS244) and 2100 ohms
+- 150 (TD2440) If amplifier is proven
defective, install
replacement
If reading is incorrect,
replace T244,
TS244/TD244 or repair
wiring