How to Replace a TXV

James Hill gives a step-by-step description of how to replace a residential indoor TXV on a heat pump system. He also removes the liquid line filter-drier from the outdoor unit and moves it outside the outdoor unit.

When replacing a TXV, you must recover the refrigerant. (As a best practice for quick recoveries, try to keep the tank as cool as possible. James uses a fan, but you may also use a hose with cool water or an ice bucket.)

First, James removes the line drier from the outdoor unit and brazes in a copper stem to fill in the empty space. He does a quick leak detection on the condenser before moving on to the air handler. There wasn’t enough room to fit the filter-drier indoors, so James installs it outside the condensing unit for ease of serviceability.

The TXV bolts onto the unit, so there’s no need to braze in the new TXV. While replacing the TXV, James also had to replace the washers and strap the new sensing bulb to the suction line. Insulating the bulb may also be a recommended practice per the manufacturer, but James does it anyway because it won’t hurt anything.

After the new TXV is installed, James pulls a deep vacuum with the TruBlu evacuation kit, including the large TruBlu vacuum hoses. He also removes the Schrader cores for a fast and deep vacuum. After the decay test finishes, James charges the system to factory specs. Then, the charge equalizes as the unit runs, and James’s readings allow him to be confident that he’s done the job right.

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