The upstairs runs hotter than the rest of the house
Lake Oswego’s median home dates from 1982, and many houses here have a gas furnace on the lowest floor and ducts throughout. Most of them work well, except upstairs.
The bedroom wing sits at the end of the shortest branches and shares one return downstairs, so it lags the rest of the house in every season.
What we do about it
Firlands Portland Mini Splits gives those rooms a system of their own, with wall heads or a slim ducted unit hidden in the attic, and leaves the furnace with the floors it already heats well.
Why the bedrooms lag
- small supply branches sized for heat, not cooling
- one return at the bottom of the stairs, so warm air upstairs never gets pulled back
- a thermostat on the main floor that doesn’t know the bedrooms exist
Project
Inside a Mountain Park bedroom wing, ducted from the attic
The problem
The three upstairs bedrooms run 6 to 8 degrees warmer than the main floor in summer and lag behind it in winter. The owners don't want three wall heads on the bedroom walls, and they don't want to replace a furnace that's only eight years old.
The house
The furnace sits in the lower level with its trunk in the floor joists; the upstairs gets three small branches and shares one return at the bottom of the stairs. Above the bedrooms is a walkable attic with about five feet of clearance at the ridge. The City of Lake Oswego issues both the mechanical and the electrical permit.
What we decide, and why
A slim ducted air handler in the attic serves all three bedrooms through short insulated ducts and one ceiling grille per room, with a return grille in the upstairs hall. The bedrooms get their own system and thermostat, the furnace keeps the two lower floors, and nothing hangs on a bedroom wall. Three wall heads were the alternative: cheaper, but the owners preferred grilles.
The work
We set the air handler on a platform over the hall, with a secondary drain pan and a float switch under it, and run R-8 flex duct to three 10-inch supply grilles and one return. The line set leaves through the gable end and drops down the back wall in one cover to a pad. The primary drain falls through the attic to an outside downspout. A 25-amp, 240-volt circuit runs from the garage panel to the outdoor unit's disconnect, and a separate feed powers the air handler. The line set holds a nitrogen test and a vacuum below 500 microns, and both drain paths are tested with water.
The secondary pan and float switch shut the system off if the primary drain ever clogs, so a blocked drain can't drip through the bedroom ceiling.
What it changes
Three bedrooms that hold the same temperature as the rest of the house, no indoor units on the walls, and a furnace left to do the job it was sized for.
- Location
- Mountain Park, Lake Oswego
- House
- 1978 two-story, about 2,400 square feet, gas furnace with ducts in the lower level
- Equipment
- One slim ducted air handler (18,000 BTU) in the attic serving three bedrooms, on one 18,000 BTU cold-climate outdoor unit
- Price
- $13,250, permits included
- Time on site
- 2 days, then the City of Lake Oswego's final inspections
Wall heads, ceiling grilles or a cassette
Lake Oswego owners often ask for something that doesn’t hang on the bedroom wall. There are three ways to do it, and each one needs something different from the house.
| Option | What you see in the room | What the house needs |
|---|---|---|
| Wall head | A unit high on one wall | A stretch of outside wall, or a route to one |
| Ducted unit | One small grille per room | Attic or crawlspace room for the air handler and ducts |
| Ceiling cassette | A flush square panel | Joist space above and a condensate pump |
A ducted unit costs more than wall heads for the same rooms and is quieter in the room, because the fan sits in the attic. Ducted mini split installation covers the layout, and cassette vs wall mount compares the indoor units.
One office for both permits
Lake Oswego does its own plan review and inspection for both the mechanical and the electrical side of a mini split. That’s simpler than its neighbors.
| City | Mechanical | Electrical |
|---|---|---|
| Lake Oswego | City | City |
| West Linn, Oregon City, Happy Valley | City | Clackamas County |
| Unincorporated areas nearby | Clackamas County | Clackamas County |
We apply for both permits, include the fees in the price, schedule the inspections and close the job with the finals. We confirm your parcel is inside city limits before applying.
Keeping the furnace, or replacing it
Most Lake Oswego callers have a gas furnace that works. The question is whether to add a mini split beside it or replace the whole system.
When to add beside it
If the furnace is reasonably new and the main floors are comfortable, a system for the bedroom wing or one problem room fixes the complaint for less than a new central system.
When to look at the whole house
If the furnace is near the end and the ducts reach every room, a ducted central heat pump may be the better buy. On PGE’s rates it matches a 95% gas furnace on running cost once it averages a COP of about 2.8. Mini split vs a central heat pump compares them.
Electric heat in about four in ten homes
About 41% of Lake Oswego homes heat with electricity, often baseboards or wall heaters in houses and condos from the 1960s and 1970s.
In those homes a mini split changes the bill most, and Energy Trust of Oregon’s ductless incentive applies when the system replaces electric resistance heat in the main living space. Lake Oswego is PGE territory, so it’s $800 for a single-family home and $1,800 for condos, townhouses and rentals. Multi-zone installation covers two or more heads on one outdoor unit.
Condos and townhouses near the lake
About 8% of Lake Oswego’s homes are in buildings of 50 units or more, many of them condos.
What the association decides
- where the outdoor unit can sit: a balcony, a roof stand or a ground pad
- the route the line set takes, often a shared chase or an approved exterior cover
- the cover color and any screening
We prepare the drawings and equipment details for the board before scheduling the install. Condo mini split installation covers the approval process.
Smoke summers and closed windows
Late-summer wildfire smoke drifts over the metro in some years, and that’s when cooling matters most: you want the windows shut.
A mini split lets you keep the house cool with everything closed.
What the filters catch
Its filters catch dust and coarse particles, but they aren’t HEPA filters, so for heavy smoke a portable air cleaner in the bedroom does more. Do mini splits filter wildfire smoke? explains the difference. After a smoky summer, a deep cleaning of the heads typically runs $200 to $450 each; see cleaning and maintenance.
Steep lots, trees and the outdoor unit
Lake Oswego’s hills, its trees and the lake itself all affect where the outdoor unit can go.
- Slopes. A wall bracket or a stand near the house beats a pad at the bottom of the yard, where line sets get long and cold air pools.
- Trees. We keep the unit out from under trees that drop needles and leaves into the coil, and away from a roof valley.
- Neighbors. On close lots, the unit goes away from bedroom windows, yours and theirs.
Sizing a system for the bedroom wing
A bedroom wing gets sized from the rooms’ combined load, not from the square footage of the upstairs.
We take each bedroom’s windows and which way they face, the attic insulation above it and the ceiling height, and work out its load. Three bedrooms of about 150 square feet each often come out between 15,000 and 18,000 BTU together.
Why that matters at night
A ducted unit or a multi-zone outdoor unit sized to that total turns down quietly at night, when only one or two rooms are calling. Mini split sizing explains the method.
Lake Oswego prices
Firlands’ typical range for one head is $4,000 to $8,500, for two heads on one outdoor unit $6,500 to $12,000, and for three or four $9,000 to $18,000 and up.
A concealed ducted system typically runs $8,500 to $16,000 and up, and a ceiling cassette sits between a wall head and a ducted unit in cost. Mini split installation cost in Portland breaks down what’s inside each number.
From First Addition to Mountain Park
Across town, the age of the house and the slope of the lot set the job.
- First Addition and Evergreen. The older houses near downtown, where an upstairs without ducts calls for wall heads or a ducted unit in the attic.
- Lake Grove, Westlake and Palisades. 1960s to 1980s houses with a bedroom wing that lags the furnace.
- Mountain Park and Forest Highlands. Hillside houses and condos, with attics and steep lots that suit ducted units and brackets.