Q: I have a client who is concerned about the possibility of rodent damage on a newly installed mini-split system. How can you critter-proof a heat pump condenser unit?

A: Eric Hartman, owner of Harvestar, a home performance contractor in Lincoln, Vt., responds: In winter, when the mini-split system is in heating mode, mice have a tendency to hang out in gaps between the round insulated refrigerant lines (which are warm) and the rectangular line cover concealing them. So, it’s important to close off the ends of the protective line cover.

We install Fortress line set covers to protect the refrigeration lines between the house and the outside condenser. Their end fittings are tapered and fit tightly to the refrigerant line’s insulation. But mice can squeeze through pretty much everything. If a customer complains about a rodent problem, we seal gaps with a combination of steel wool mixed with silicone to thwart mice; they chew into the silicone a little bit, then hit the steel wool and quickly find a different place to go.

One last note: If you have cold-climate heat pump, it should be mounted off the ground on a stand because of snow. A side benefit to a stand is it reduces the likelihood of mice intrusion.

Heat pump stands, commonly installed today for cold-climate heat pumps, also reduce the likelihood of rodent damage; mice have difficulty climbing the thin factory-finished legs.
Heat pump stands, commonly installed today for cold-climate heat pumps, also reduce the likelihood of rodent damage; mice have difficulty climbing the thin factory-finished legs.

Photo by Tim Healey

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