Closing Up Your Grand Lake House for Winter: The Complete HVAC Checklist
Whether you head south for the winter or just visit the lake house less often from November through March, these steps will protect your home's HVAC system, prevent frozen pipes, and keep mold at bay until you return in the spring.
Grand Lake O' the Cherokees has thousands of seasonal homes — families from Tulsa, Dallas, Kansas City, and beyond who spend Memorial Day through Labor Day at the lake, then close up shop for winter. We have seen what happens when homes are not properly winterized: burst pipes, mold blooms, rodent infestations in ductwork, and HVAC systems that will not start come spring. All of it is preventable with this checklist.
The HVAC Winter Checklist
✅ Before You Leave (The HVAC Must-Do List)
- 1
Set the thermostat to 55-60°F — Never turn heat off completely. This prevents pipe freezing while keeping utility costs minimal. A smart thermostat lets you monitor from your phone and alerts you if temps drop dangerously.
- 2
Replace the air filter — Install a fresh filter so the system runs efficiently all winter. A clogged filter makes the furnace work harder and can cause it to overheat and shut down — exactly what you don't want in an empty house.
- 3
Schedule a fall tune-up — Have your heating system inspected before you leave. A technician can catch a cracked heat exchanger, failing ignitor, or low refrigerant BEFORE it fails mid-January with nobody home to notice.
- 4
Set the fan to CIRCULATE — Many thermostats have a circulate mode that runs the fan 15-20 minutes per hour. This prevents stagnant air pockets and distributes heat evenly, which is critical in lakefront homes where one side often faces cold north winds.
- 5
Cover but don't seal the outdoor unit — A breathable condenser cover keeps debris and ice off the unit without trapping moisture (which causes rust). Do NOT wrap it in a tarp or plastic — that creates a rodent condo.
✅ Plumbing Protection (HVAC-Adjacent but Critical)
- 6
Open cabinet doors under sinks — Especially on exterior walls. This lets warm air from your heating system reach the pipes. It sounds simple. It prevents 90% of pipe-freeze calls we get for occupied homes.
- 7
Insulate exposed pipes — Especially in crawlspaces and under pier-foundation homes common around Monkey Island and Ketchum. Pipe insulation foam is cheap and takes minutes to install.
- 8
Consider shutting off the main water supply — If you won't visit for months, this is the safest approach. Drain the lines by opening faucets after shutting off the main. If you visit occasionally, leave water on with heat running.
✅ Pest Prevention (They Love Your Ductwork)
- 9
Seal duct penetrations — Mice, squirrels, and raccoons enter ductwork through gaps where ducts pass through floors and walls. Steel wool + caulk at every penetration point keeps them out.
- 10
Check the condenser for nests in spring — Before you fire up the AC in April or May, visually inspect the outdoor unit for rodent nests, wasp nests, and snake habitation. We find them all at Grand Lake. Do NOT turn on a unit with a nest inside.
🔴 The #1 Winter Disaster We See
Every winter, we get calls from Grand Lake homeowners who arrive to find water damage from burst pipes. The story is almost always the same: the power went out during an ice storm, the heat stopped, and pipes froze before power was restored. If you have a smart thermostat with cellular backup, you'll get an alert. If not, consider having a neighbor or property manager check on the house after any major winter storm. Better yet — a freeze sensor (available at any hardware store) texts you when indoor temps drop below 40°F.
We'll Help You Close Up Right
Cozy Llama offers fall winterization tune-ups specifically designed for Grand Lake seasonal homes. We inspect the heating system, check ductwork for pest entry points, verify thermostat programming, and confirm everything is ready for an unattended winter. Llama Loyalty Club members get priority scheduling and discounted rates.