Sometime within the next five years, you may find that you need to replace your HVAC split system air conditioner or heat pump. Whether you live in a single home, a condominium, or and independent living apartment, here are some of the questions that you will need to answer.

R22 refrigerant and its HFC replacement R410A are totally incompatible. Your existing condensing unit and cooling coil are not suited to the new higher pressure refrigerant. It is possible to reuse the copper tubing lineset between the two, but we will discuss that later.

The new condensing unit and coil will be physically larger than the old unit. If your condensing unit is on a midrise condominium rooftop with dozens of other condensing units, they may need to be remounted in such a way that provides the manufacturer’s recommended clearance between units. The coil will be taller than the old one, and will not fit in the metal coil enclosure at the air handling unit. This enclosure will have to be rebuilt, or you may have to buy a new air handler that provides a greater airflow required by the new coil.

Consider buying the highest efficiency model that you can afford. There is obviously a premium to pay for the most efficient models, but some level of higher efficiency may be affordable.

The conventional wisdom is that the copper lineset should always be replaced. While this is true, it is not always practical to do so. Generally, you will not save money by reusing your old lineset. It will have to be flushed with nitrogen and a solvent, then modified for reuse. The labor and materials needed to do this will equal the cost of replacing the lines. If your line routing is inaccessible (under a concrete slab) you may want to seriously consider reusing the tubing.

Not all linesets may be reused. Your contractor will perform a calculation to determine whether it is possible. Generally speaking, the coil must be within 25 to 50 feet of the condensing unit for line reuse to be possible. A larger line size will be needed beyond that distance.

If the condensing unit is close enough to the coil, the lines might be reused after flushing with nitrogen and a chemical flush such as RX11 Flush, Qwik System Flush, or Diversitech Pro Flush. Years ago, the line flush was done with R11 refrigerant. This is now banned by the EPA, so if your contractor suggests it – say no. You should also consider the age of the existing lines. You may not want to reuse 25-year-old lines, but if they are only 12 or 15 years old, it may be okay. I would always replace the lines if it is feasible. New or larger sizes may be required, in which case a new line set would need to be routed near the existing lineset. Drain and remove the old lineset.

For a good description of how to flush your lineset, visit Robert Scaringe’s article, http://contractingbusiness.com/refrigeration/cb_imp_77425

zumBrunnen, Inc.

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