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TANKLESS
WATER HEATERS
Models & Prices
Tankless Water Heater Product Guide
Description / Specification
Tankless Water Heater Applications
Residential / Commercial
Tankless Water Heater Electrical Guide
Service Calculations
Tankless Water Heater Installation
Plumbing / Electrical
Tankless Water Heater Cost Comparisons
Reports / Listings
Tankless Water Heaters Service Guide
Remove / Repair
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CHANGING THE CONTROL
BOARD
Required
Tools: Needle
nose pliers, Phillips and slotted screw drivers, heat sink compound (or
thermal grease) and a battery powered voltmeter.
WARNING:
To avoid electrical shock, make sure
that all of the power is off to the heater before attempting to remove
the old control board and while installing the new control board.
- Turn off all the power to the heater. Confirm
the power is off with a voltmeter, even if the status light (or
LED) on the control board is off. There may be multiple breakers powering
your model heater.
- You may want to label the incoming power wires
to make replacement easier and to avoid installing them out of phase
or out of sequence. With a slotted screw driver, remove the power
wires from the screw lugs on the right hand side of the board.Using
a pair of needle nose pliers, pull all of the control wires off
the spades on the circuit board. Be sure to pull on the connector, not
the wire.
Figure: Control
board power lugs (L1 & L2) and
the triacs attached with Phillips head
screws
- Using a Phillips head screw driver, unscrew the
triacs from the heat sink to the right of the board. Take care that
the screws are not lost, they will needed for the new board.
- Using a Phillips head screw driver, remove the four
mounting screws from the board, be ready to support the board as you
remove the screws. Be careful not to get the white heat sink compound
on your clothing, as it is difficult to wash out.
- Place heat sink compound on the triacs being careful
not to bend the leads. Be sure to get a thin coating covering the entire
back of the triacs, if you don’t, they will burn out as soon as
you power up the heater. To maximize thermal conduction, it is advisable
to clean the backs of the triacs with alcohol before applying the heat
sink compound.
- Loosely mount the board to the heater with at least two Phillip
head screws. Screw the triacs down to the heat sink; be sure they are
flat against the heat sink. Don’t twist the head off of the screw,
if you feel any resistance, back the screw out and try again.
- After the triacs are snug, tighten down the board screws (8
in.-lbs.). Don't tighten them so much that you bend the board.
- Replace the main power wires into the screw lugs and tighten.
If the wires are stranded, make sure all strands are in the lug to avoid
possible shorting of the control board.
- Replace the control and element wires (see schematic inside
the protective cover).
- Using the "Matching Procedure" above, match the control to
the thermistors and place the heater back in service.
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