Water Heating Systems

Seisco Tankless Heaters

Electric Water Heaters

Heat Sink Replacement

The heat sink is a metallic bar (aluminum or copper) located to the right of the heating chamber and it covers part of the inlet tube. It will be necessary to remove the control board as it is attached to the heat sink.

Required Tools:

• Large & small Phillips screw drivers
• battery powered volt meter
• rag, bucket
• two pipe wrenches
• needle nose pliers
• heat sink compound an
• Teflon tape pipe sealer

Warning: To avoid electrical shock, make sure that all of the power is off to the heater before attempting to remove the old heat sink and while installing the new heat sink.

1. 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.
2. Open a hot water faucet nearby. While the water is running, turn off the water supply to the heater. This will help siphon some of the water out of the heater.
3. Using a large Phillips screw driver, remove the six screws from the right bottom clean out plate on the under side of the heating chamber (there is only one clean out plate on a two chamber heater) to drain the remaining water from the heater into a bucket. Replace the plate after draining.
4. Remove the control board according to procedure A. Changing The Control Board.
5. Using two pipe wrenches, disconnect the incoming water line threaded onto the top of the inlet fitting. Use the rag to prevent any water dripping or spraying, which should be very little if any.
6. Remove the two screws from the top of the heat sink and the two screws from the bottom. This will require rotating the heat sink to gain access to the screws. Also, there are holes through the right side of the metal casing to allow the screw driver to fit through.
7. Slide the top inlet tube up and out of the heat sink. There are two o-ring seals on the inlet tube.
8. Slide the heat sink up and off the lower inlet adapter tube and remove the heat sink. At this point, if necessary, the lower inlet adapter tube can be removed for replacement.
9. Replace the heat sink and re-assemble in the reverse order
10. Wrap the Teflon tape pipe sealer around the threads of the inlet fitting and reconnect the incoming water line. Do not use Plumber’s Putty or Pipe Dope on the threads of the inlet and outlet fitting connections. If using CPVC or PVC primer and glue, avoid contact of these substances with the inlet and outlet fittings on the heater. These substances are highly corrosive and can damage the inlet and outlet fittings. Leaks may occur as a result and cause severe damage to the heater.
11. Turn on the water and check for leaks.
12. Re-install the control board and turn on the power to the heater. Make sure that all of the circuits are on to power the heater.

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