What Is a Manual J Load Calculation, and Why Should an HVAC Quote Include One?
A Manual J load calculation works out how much heating and cooling your house needs. What goes into it, why the old nameplate oversizes and what to ask.
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Heating & Cooling in Stillwater, MN
Stillwater's North Hill and South Hill are lined with houses from the 1800s lumber boom, while newer neighborhoods such as Croixwood and Liberty on the Lake fill in the rest of the city.
HVAC service in Stillwater, MN
We repair and replace furnaces, air conditioners, heat pumps, boilers and ductless mini-splits in Stillwater and across Washington County. Every visit starts with a $79 trip charge and a written price before any work, and the $79 is waived when you go ahead with the repair.
- County
- Washington County
- ZIP code
- 55082
- Natural gas
- Xcel Energy
- Electric
- Xcel Energy
- From downtown Minneapolis
- about 23 miles
Updated September 23, 2026
What HVAC problems do we see most in Stillwater?
- Boiler replacements and radiator repairs in 1800s homes on the North and South Hills
- Small-duct high-velocity or ductless cooling for plaster-walled houses that can't take full-size ducts
- Chimney liner and combustion-air corrections found when old flues are inspected during a furnace swap
- Builder-grade furnace and AC replacements in the west-side subdivisions
Around town: Stillwater Lift Bridge · St. Croix River · Historic Washington County Courthouse · Stillwater Commercial Historic District · St. Croix Crossing. Neighborhoods: North Hill · South Hill · Croixwood · Liberty on the Lake
Book in StillwaterWhat are Stillwater homes like to heat and cool?
Stillwater's housing reads like a timeline climbing out of the river valley. The North and South Hill houses from the lumber decades are often balloon-framed, with wall cavities that run from basement to attic, stone foundations, and basements never meant to hold a furnace and its ductwork. After World War II, better roads put Stillwater within commuting range of the Twin Cities, and newer houses began filling the edges of the old town.
The first planned subdivisions came in the 1970s west of downtown, led by Croixwood, laid out along the east side of Long Lake with winding streets and lots of a quarter acre or more. Houses there have ordinary basements and ductwork, and most are on their second or third furnace. Annexation from 1996 on added the city's youngest neighborhoods on the west side. So a furnace or boiler question in Stillwater starts with which of those three eras the house belongs to.
Winter in Stillwater
The St. Croix valley holds cold air on still winter nights, and downtown and the lower streets can sit colder than the hilltops. The old houses feel it most. Balloon-framed walls without fire blocking let cold air move from basement to attic, and radiators under tall windows fight a constant downdraft. Chimneys on these houses are tall and exposed, which helps them draft but lets the masonry deteriorate where flue gas condenses inside. A liner inspection belongs in any boiler or furnace swap.
Summer in Stillwater
Summer humidity along the St. Croix can be heavy, and the valley traps it on still evenings. The old houses on the hills get cooled in pieces: window units, ductless heads, or a small-duct system in the attic serving the top floor. Croixwood's 1970s houses usually have ductwork that can carry central air, though the original returns tend to be small for modern equipment. In the newer west-side homes, the question is mostly whether a builder-grade AC was sized right in the first place.
Which utilities and rebates apply in Stillwater?
Stillwater homes buy gas and electricity from Xcel Energy, which keeps the rebate picture simple. On the North and South Hills, the Xcel rebate that matters most is the one for high-efficiency gas boilers; on the west side it's usually a furnace, central AC or heat pump. Mini-split and cold-climate mini-split heat pumps, a common way to cool radiator homes, have their own Xcel rebates. Some Xcel rebates require a registered contractor, so ask before you choose equipment.
Rebate programs change every year; check the utility's current terms before you buy. Our guides: Xcel and CenterPoint rebates, heat pump rebates, what happened to the federal credits.
Most-requested in Stillwater
Furnace repair in Stillwater Stillwater furnace repair with us begins at a $79 trip charge, which is waived when you approve the repair. Furnace replacement in Stillwater Furnaces we install in Stillwater cost $4,500–$9,500: roughly $4,500–$6,000 for 80% AFUE and $6,500–$9,500 for 96–98%. AC repair in Stillwater Humid July air along the St. Croix keeps drain lines and condensate pumps working hard in Stillwater. AC replacement in Stillwater West-side two-stories in Stillwater usually get a new condenser and matched coil, while plaster-walled houses on the hills without ducts suit small-duct high-velocity or ductless equipment.
All services in Stillwater
Stillwater HVAC questions
Who repairs furnaces and air conditioners in Stillwater, MN?
Central Minnesota Heating and Cooling serves Stillwater and the rest of Washington County, about 23 miles from downtown Minneapolis. We repair and replace furnaces, central air, heat pumps, boilers and ductless mini-splits, and we're open 7 days, 7am–9pm. Call 612-429-3465.
How much does an HVAC service call cost in Stillwater?
A flat $79 trip charge, waived when you approve the repair. Written price before any work; same prices in every town we serve. Installed prices are on our pricing page.
Can you put central air in a North Hill house without wrecking the plaster?
Usually, yes. Small-duct high-velocity systems run flexible two-inch tubing through closets, attic space and floor cavities to small round outlets, so the plaster stays mostly intact. Ductless mini-splits are the other route when only a few rooms need cooling. In three-story houses we often put an air handler in the attic for the upper floors and treat the main floor separately.
Does my historic Stillwater house need approval for a new vent or condenser?
It can. Stillwater has a Heritage Preservation Commission, and changes to the outside of a designated property may need review before work starts. A high-efficiency furnace needs two PVC pipes through an exterior wall, and a condenser needs a pad and clearance around it. We look for the least visible spots the code and the manufacturer allow, and if your house is designated, we check with the city before scheduling.
Can a condensing boiler in our historic Stillwater house vent without new pipes on the front?
Usually. Many condensing boilers can vent up through the old chimney using a liner kit the manufacturer approves, which keeps new pipes off the outside walls entirely. Where a sidewall vent is simpler, we look for a side or rear wall where the pipes are less visible, and check with the city first if the house is designated. The old chimney still needs inspecting either way.
Can our Stillwater boiler heat a new addition?
Usually, if it has spare capacity. A new zone with its own circulator or zone valve and thermostat can feed panel radiators, baseboard or radiant floor tubing in the addition. We run a heat-loss calculation on the whole house to confirm the boiler can carry it; old boilers are often oversized, so there's room. Cooling the addition is a separate question, and a ductless head is the usual answer.
Also serving near Stillwater
- Oak Park Heights, MN 2 mi
- Bayport, MN 3 mi
- Grant, MN 5 mi
- Hudson, WI 6 mi
- Lake Elmo, MN 6 mi
- Mahtomedi, MN 7 mi
- White Bear Lake, MN 9 mi
- North St. Paul, MN 10 mi
Guides for Stillwater homeowners
Aux Heat vs Emergency Heat on a Heat Pump Thermostat
Aux heat comes on by itself to help a heat pump; emergency heat is a manual switch for a failed heat pump. When each is normal in Minnesota and what it costs.
Read the guideTurning the Furnace On for the First Time This Fall
Turning the furnace on for the first time this fall? What to do first, which smells and sounds are normal, and the filter, humidifier and CO alarm steps.
Read the guide- Integrated HVAC Smoke Detection: How Duct Detectors and Fan Shutdown WorkAir Quality
- Where to Put Carbon Monoxide Alarms in a Minnesota HomeAir Quality
- Furnace Won't Ignite: Find Where the Startup StopsHeating
Brands we service in Stillwater: AirEase · Amana · American Standard · Ameristar · Aprilaire · Arcoaire · Armstrong Air · Bosch · Broan-NuTone · Bryant · Buderus · Burnham · Carrier · Champion · Coleman · Comfortmaker · Concord · Daikin · Day & Night · Ducane · ecobee · Frigidaire · Fujitsu · Gibson · Goodman · Google Nest · Gree · Heil · Honeywell Home · Lennox · LG · Lifebreath · Lochinvar · Luxaire · Maytag · Midea · Mitsubishi Electric · MrCool · Navien · NTI · Payne · Peerless · Rheem · Rinnai · RunTru · Ruud · Samsung · Santa Fe · Tempstar · Trane · Triangle Tube · Utica Boilers · Viessmann · Weil-McLain · Westinghouse · York
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Heat out in Stillwater? Call or send a request.