How to Retap a Thread Heat Exchanger
A heat exchanger is an important part of your HVAC heating and cooling system. It takes cold air in the winter and converts it to warm air, then it takes warm air in the summer and converts it to cold air. If you completed maintenance on your heat exchanger and stripped out one of the threaded mounting holes on your HVAC unit, you can re-tap the hole so you can reattach the heat exchanger. Does this Spark an idea?
Instructions
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1
Select the next sized larger bolt for your application. For example if the original bolt size is 1/2-inch, select a 5/16-inch bolt that matches the same length as the original one.
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2
Select the proper drill bit for the size bolt you choose. When re-tapping a hole, you must use a drill bit that measures smaller than the tap size. For example, if you plan to use a 5/16- inch bolt, you will need a 5/16-inch tap and a 9/32-inch drill bit.
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Secure the drill bit to a hand drill. Center the drill bit over the existing hole, then drill out the hole until the bit reaches the bottom. Hold the drill bit perpendicular to the hole at all times, to ensure you drill straight down into the hole.
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4
Attach the tap to the T-handle. Hold the tap perpendicular to the hole. Apply downward pressure on the T-handle with one hand, while you turn the T-handle with the other. After two or three turns, back the tap out of the hole to clear out the chip. Continue doing this until you reach the bottom of the hole with the tap.
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Back the tap all the way out of the hole, then turn the tap in one more time to smooth out the threads.
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Tips & Warnings
Most drill taps have two numbers printed on them. The first is the size of the drill tap and the second is the size of the hole required for the drill tap.
