We have a problem. Specifically a 5 ton Trane Heat Pump unit (residential) is emitting a high pitched noise from the air intake/exhaust when operating in the heating mode. Currently, ther system has a single double cased pipe penetrating to the outside. In an attempt to solve this problem this single intake/exhaust was relaced with two sepatare lines. This had no effect on the noise, and have since returned to the single double piping.
Has anyone run into this before? And if so, any ideas on how to fix it?