LAARS Mighty Therm LO-NOx VW (Sizes 250/400) - Installation, Operation and Maintenance Instructions - Manual (Page 25)

Mighty Therm LO-NOx Volume Water Heater Page 25
2. Voltage outside of the required range may be due
to poor wiring connections, to other loads (e.g.,
air conditioners, compressors) on the circuit, to
high pump load, or to an electrical utility
company problem.
5.2.4 Testing the Manual Reset
Hi-Limit Switch
To test the manual reset hi-limit switch (see
Figure 38):
the short must be found and repaired. Do not
jumper or bypass the fuse.
6. Make sure the electrical circuit to the heater is
on.
7. Make sure the toggle switch on the right side of
the heater is on.
8. Make sure the temperature control is set high
enough to call for heat.
9. Make sure the manual reset on the safety controls
(e.g., low water cutoff, hi-limit switch, etc.) has
not tripped. If it has, reset it.
If the pump is circulating water, and the rest of
these items check out all right, the trouble could be in
the heater control system.
Caution
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after
servicing.
Attention
Au moment de l’entretien des commandes,
étiquetez tous les fils avant de les débrancher. Les
erreurs de câblage peuvent nuire au bon
fonctionnement et être dangereuses. S’assurer que
l’appareil fonctionne adéquatement une fois
l’entretien terminé.
5.2.2 Testing the Transformer
NOTE: Keep the pump running.
Testing the transformer requires an AC voltmeter
with a 50 volt (V) range. Test the transformer using the
following procedures:
1.
Clip a lead from the voltmeter to the yellow wire
terminal on the transformer (this lead stays
connected to this terminal for all tests).
2. Touch the other lead to the red wire terminal (see
Figure 37). The voltmeter should read 20 to 28VAC.
3. If the voltmeter does not show voltage, check the
electrical power supply.
4. If the voltage is less than 20VAC, the electrical
circuit to the heater may be supplying less than
103VAC. This could be due to high pump load or
air conditioners or other appliances on the circuit.
5.2.3 Testing the Electrical Power Supply
The electrical components of the VW and PW
heaters operate with supply voltage ranging from 103
to 126VAC at 60 Hertz (Hz). To test the electrical
power supply:
1. Measure the voltage at the hot and neutral
connections inside the heater electrical junction
box.
Figure 37. Testing the Transformer.
Figure 38. Testing the Manual Reset Hi-limit Switch.
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