Half the houses heat with electricity
Most Oak Grove calls start with two things: a baseboard heating bill and a Milwaukie mailing address. About half the homes here heat with electricity, in houses from the 1950s to the 1970s and an older stretch near the river.
Baseboards are where a heat pump changes the bill most. Firlands Portland Mini Splits starts with the living space, sizes each head to its room, and handles the Clackamas County permits that Oak Grove’s unincorporated status brings.
The mix of houses
- 1950s to 1970s ranches and split-levels on baseboards
- duplexes and small plexes, many with an owner on one side
- older homes along River Road and near the Trolley Trail, some with basements and upstairs rooms
Project
Inside an Oak Grove duplex, one system per side
The problem
Each side heats with baseboards, and the owner, who lives in one side and rents the other, pays for the bills on her side and hears about them on the other. Neither side has cooling.
The house
Each unit has its own meter and panel in the utility closet, an open living and dining room at the back, and two small bedrooms at the front. A shared attic runs over both, with a fire separation at the party wall. The address has a Milwaukie mailing address but sits in unincorporated Clackamas County, so the county issues both permits.
What we decide, and why
One shared multi-zone outdoor unit ties both households to one compressor and one meter, so each side gets its own system. A 12,000 BTU head goes high on the back wall of each living room, throwing air toward the bedroom hall. The bedrooms keep their baseboards. Each outdoor unit sits on its own pad behind its own unit, at opposite ends of the back wall, so neither one sits under a bedroom window.
The work
Two three-inch holes, one per side, each line set straight through the wall behind its head with a short cover to the pad. Each side gets a 20-amp, 240-volt circuit from its own panel, run through its own half of the attic without crossing the fire separation, and a disconnect beside its outdoor unit. The living-room baseboard circuits come off. Each line set holds a nitrogen pressure test and a vacuum below 500 microns, and both drains fall to the yard by gravity.
We schedule the rented side's day with the person living there a week ahead, contain dust around the wall opening, and finish that side in one day so their living room is back in use by evening.
What it changes
Each household controls its own heat and cooling on its own bill, the living-room baseboards come off on both sides, and because both systems replace electric resistance heat in a duplex's main living space, each side can qualify for Energy Trust's $1,800 incentive.
- Location
- Oak Grove, near Oak Grove Boulevard and the Trolley Trail (unincorporated Clackamas County)
- House
- 1966 side-by-side duplex, two 2-bedroom units of about 900 square feet, electric baseboards
- Equipment
- Two separate single-zone systems: one 12,000 BTU cold-climate head and outdoor unit per side
- Price
- $13,600 for both sides, permits included
- Time on site
- 2 days, then the county's final inspections
A Milwaukie address, a county permit
Oak Grove isn’t a city. It’s unincorporated Clackamas County, so the county issues every building permit here, mechanical and electrical.
Most Oak Grove addresses mail as Milwaukie, and the City of Milwaukie warns that a Milwaukie mailing address doesn’t put a home inside its limits. We check your parcel on the county’s map before applying.
| What we apply for | Who issues and inspects it |
|---|---|
| Mechanical permit: heat pump, heads, line sets | Clackamas County Building Codes |
| Electrical permit: new 240-volt circuit and disconnect | Clackamas County Building Codes |
The fees are in our price. Mini split permits explains what each permit covers.
Duplexes and the people living in them
Oak Grove has its share of duplexes, and where the owner lives on one side and rents the other, both sides need planning.
Two systems or one
With two meters and two panels, we put a separate system on each side. A shared multi-zone unit is cheaper by a little and costs more later, because both households lose heat when it needs service.
Scheduling around the rented side
We give the person living there a week’s notice, contain the dust around each wall opening, and finish their side in a day. Mini split for rental property covers access and notice in more detail.
The incentive, side by side
Oak Grove is PGE territory, so Energy Trust of Oregon’s ductless incentive applies when a ductless system replaces electric resistance heat in the main living space.
| Your home | Energy Trust’s ductless incentive |
|---|---|
| Owner-occupied single-family house | $800 |
| Owner-occupied duplex, triplex or fourplex | $1,800 per qualifying home |
| Any rental | $1,800 |
The heads need an HSPF2 of 8.10 or better, the contractor signs the application, and it goes in within 60 days of the install. Gas-heated homes don’t qualify for this offer. Mini split rebates in Oregon lists the conditions.
Older houses near the river
Along River Road and the streets toward the Willamette, Oak Grove has houses from the 1910s to the 1930s, about as many pre-1940 homes, as a share, as Milwaukie.
Those houses often have a basement, plaster walls and rooms under the roof with no ducts.
How the work changes
A head in an upstairs room usually runs its line set down the back wall; a basement head often needs a small condensate pump. Before 1978, paint and plaster may contain lead, so we set up dust containment before coring a wall. Basement mini split installation covers the lower floor.
Where the outdoor unit goes on an Oak Grove lot
Most Oak Grove lots have room behind the house, so the outdoor unit usually goes on a pad at the back, out of sight from the street.
What we look for
- a spot within the line-set limits of every head it serves
- at least a foot from the wall, and clear of a gutter outlet or roof valley that drops water on it
- away from a bedroom window, yours or the neighbor’s
- a stand above the ground where the yard holds water in winter
On a narrow lot or a duplex with a shared back yard, a wall bracket keeps the unit off the lawn and out of the way. Mini split placement shows the options.
An old mini split that’s quitting
Some Oak Grove houses already have a mini split from 10 or 15 years ago. When it starts failing, the first question is whether the line set can stay.
We pressure-test the old line set with nitrogen and pull a vacuum. If it holds and the new unit’s refrigerant and pipe sizes match, a like-for-like swap is the simpler job; Firlands’ typical range for that is $4,000 to $8,000. If it fails, the lines are replaced too. Mini split replacement covers the choice.
Which rooms get heads first
In a baseboard house we start where the heat costs most and work outward from there.
- The living space. It runs its baseboards longest, and replacing them there is what qualifies the incentive.
- The bedroom used most. Often the hottest room in July as well.
- Small rooms later. They keep their baseboards; an outdoor unit sized with spare capacity can take another head without being replaced.
Baseboard to mini split covers the conversion step by step.
Winter and summer on the river
Clackamas County’s heating design temperature is 24°F, and its summer design high is 88°F. The 2021 heat dome blew past both, with Portland’s airport at 116°F.
We size each head for both ends: enough heat at the design low, checked below it on a cold-climate unit, and enough cooling for a west-facing room on an 88°F afternoon.
Not sized for the record
An oversized head handles the heat wave and then short-cycles the rest of the year, so we don’t size for the record. Do mini splits work in cold weather? explains the winter side.
What goes into an Oak Grove price
Firlands’ typical range runs $4,000 to $8,500 for one head, $6,500 to $12,000 for two on one outdoor unit, and $9,000 to $18,000 and up for three or four.
A duplex with two separate single-zone systems is priced as two single-zone jobs on one estimate. Taking baseboard circuits off often frees enough breaker space to avoid a panel upgrade. Mini split installation cost in Portland has the full list of drivers.