Rinnai REU-16 Service Manual page 36

Diagnostic Checks
O. 3 Amp Fuses
The unit has two 3 Amp fuses on the pcb and one in the moulded plug lead. Remove
the fuses and check for continuity through. If there is continuity the fuse is good, if not
replace it.
P. Transformer.
There is one transformer on the 16i located in the back above the cold water connection
with the flow sensor and servo. To access it remove the top and bottom screw holding in
the pcb and pull the pcb out. Let it hang from its wires, but be careful not to damage it or
pull on it.
Test the transformer in standby mode (unit on, water off.)
First check the voltage from the pcb. The white wires from the pcb connection H go
directly to the transformer, so if there is power from the pcb there is power to the
transformer (check for loose connections.) From the transformer come five wires. These
run back to the pcb connection D. Check the voltage from the transformer at this pcb
connection. With your meter check Voltage AC by putting your leads in to the connector
(while connected.)
White – White 200 – 240 Vac. If incorrect confirm power to pcb, then replace pcb.
11 -20 Ohms.
Conn D
Brown – Blue 12 – 14 Vac
Yellow – Blue 200 – 240 Vac
Orange – Orange 50 – 60 Vac
If any of these are incorrect replace the transformer – assuming the White – White
voltage is correct.
Q. Filter.
Below the water heater, on the cold water connection is a brown or black plug. Isolate
the water supply, open the pressure relief valve on the heater, and remove this brown
plug. It holds a small, 30 micron, basket strainer. The strainer becomes clogged easily,
especially after installation. When it is clogged sometimes water will travel through the
unit without triggering the flow sensor. Make sure you check any external Y-strainers as
well.
When finished cleaning the filter replace it and screw it in finger tight. Next open the cold
water valve slowly (do not close pressure relief valve before this.) There will be a bit of
water blown out of the pressure relief valve and then the air will be pushed through.
Once the air stops and water comes out of the valve tighten it up. Now open the hot
water valve and cold water valve fully. This will prevent air locks.
If incorrect replace transformer.
(0.7 – 1.3 Ohms)
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