Off Duty Heating and A/C · Granite Shoals, TX · From the truck

Four Window Units and a Box Fan. The Cottage Deserves Better.

Plenty of houses on the Granite Shoals side of Lake LBJ began life as a fishing place. A room went on one decade, a porch got closed in the next, and somewhere along the way a window unit got wedged into nearly every new wall. Now the place is a real home, maybe a full-time one, cooled by a row of boxes that each hum at a different pitch.

Retiring those units is one of the better upgrades an old lake cottage can get. The hard part is choosing a replacement for a house that was never planned as one building, so this post covers how we size up a layered house before anybody mentions a brand.

Why Every Room Ended Up With Its Own Box

Window units are the honest record of how a cottage grew. The original core probably had one. When a bedroom wing went on, whoever built it cut a hole for another rather than stretching ductwork that did not exist. A great room added later might have picked up a small split system of its own, installed to cool that room and nothing else.

Each of those choices made sense on the day it was made. Put together, they leave a house with no single brain. One unit short cycles in a tiny bedroom, another cannot keep up with a sunroom, and none of them do much about the damp air that drifts in off the water on summer evenings.

Window units also leak air. It slips around the sash and the accordion side panels, and every gap lets humid outdoor air into the room. In a town this close to the lake, that moisture is a big part of why an old cottage can feel sticky even while the dial on the box says cool.

What Gets Mapped Before Equipment Comes Up

The first visit is mostly looking and measuring. We walk the house and note where each era starts and stops, because the seams between additions show where ducts could run and where they never will. The attic gets a look if there is one worth crawling into. Some cottage roofs sit low enough that a duct run is out of the question over half the house.

Every existing unit gets noted: what it serves and whether it keeps up. If an older split system is part of the mix, its ducts get checked for crushes and disconnections, and static pressure gets measured at its air handler, so we know whether that ductwork could carry more air or is already struggling with what it has.

Then comes the load calculation, room by room. A closed-in porch with old single-pane windows gains heat very differently from a newer bedroom wing with decent insulation. Sizing off square footage alone is how people end up with a big new system and back rooms that still run warm.

One Central System on Corrected Ducts

Sometimes the right answer is one right-sized central system. That usually works when the house has a usable attic or crawl space that reaches most rooms, and when the additions sit close enough together that supply runs do not have to snake around the entire building.

Going central in a layered house almost never means reusing the ducts already up there. Runs improvised across several renovations tend to be undersized, poorly supported, or tied into a return built for one room. So the plan includes the ductwork: a return large enough for the new airflow, trunk and branch runs laid out for the house as it stands today, and joints sealed.

The payoff is one thermostat, real filtration, and a system that pulls moisture out of the whole house at once. The cost is the attic work, and on some cottages that work simply is not practical. We would rather reach that conclusion at the kitchen table, before anyone opens the attic hatch.

Ductless Heads, One for Each Era

When the attic will not cooperate, ductless is often the cleaner path. An outdoor unit feeds indoor heads through a small line set, and each head gets its own control. The original cottage core can have one, the bedroom wing another, the great room a third. Nothing gets forced through a cramped attic, and no big openings get cut in walls that have already been patched a few times.

Off Duty is a Mitsubishi Diamond Contractor, so ductless is work we do all the time. The design still starts from the load calculation, because a head sized too big for a small bedroom will short cycle exactly the way the old window unit did, and leave the room just as clammy.

Ductless also suits the weekend houses around town. A room nobody is using can be set back on its own while the rest of the house stays comfortable, and a connected thermostat or controller lets owners check on the place before they make the drive out.

The Electrical Panel Gets a Look Too

Many cottage panels predate modern loads. They were set up for lights, a range, maybe a water heater, and then window units got plugged into whatever circuit was handy. Before a new system goes in, we look at what that panel already carries and what the new equipment will add.

Pulling window units frees some circuits, but a central system or a multi-head ductless setup needs its own properly sized circuit. If the panel has no room, or its condition raises questions, you hear about it during the assessment and the electrical side gets planned into the job before install day.

That quiet bit of homework keeps a new system from tripping a breaker during the first hot stretch of June.

Living With the Choice Afterward

Whichever way the house goes, the new system needs basic care. Filters on a central system deserve a monthly check through the first summer, since an older house tends to shed dust once air starts moving through it in new ways. Ductless heads have washable filters behind the front panel, and they need rinsing more often than most owners guess.

Lake air is hard on outdoor equipment, so keep plants and stored boats clear of the condenser and plan on a spring visit to wash the coil and clear the drain. A cottage that ran on window units for years never had a condensate line to think about, and new owners are sometimes surprised to learn they now have one.

Keep the paperwork together as well: model numbers, the load calculation, and the duct layout if you went central. For how a changeout day runs from start to finish, read our installation page, and the Granite Shoals page covers everything else we take on in town.

Can a ductless system handle the whole cottage?

Often, yes. A multi-head system can give each part of the house its own head, fed by one or more outdoor units. Whether it covers everything depends on the room-by-room load calculation and how the walls divide the space. Some layouts still do best with a central system plus a head for the rooms ducts cannot reach.

Can I keep one window unit around as a backup?

You can, though most owners pull them once the new system proves itself. A window unit left in the wall keeps leaking humid air around its edges all summer. If you want a backup for one room, a single ductless head there does the job without the draft.

Will new ductwork mean tearing up ceilings?

Usually not. Most duct work in a cottage goes in from the attic or crawl space, with registers cut in from above or below. The rooms where that cannot happen are exactly the rooms where a ductless head tends to make more sense, so the two approaches often end up working together.

Our old split system in the great room still runs. Should it stay?

Maybe. If it is sized right for the room it serves and its ducts test well, it can stay in the plan while the window units get replaced around it. If it is oversized, worn, or fed by crushed ducts, folding that room into the new system usually works out better over the years.

Do weekend owners need to be there for the assessment?

It helps to be there for the walk through, since you know which rooms run hot and at what time of day. The measuring and the attic crawl do not need anybody standing over them, so plenty of part-time owners show us around, answer a few questions, and head down to the water.