You do not need a regional climate map to understand how this house sits in the valley. Walk the parcel. The last snow to melt, the first patch of drive to glaze, the eave that grows icicles, how far up the lot the dawn fog comes, and the wall that never dries will tell you more about where a ventilator can terminate — and how hard it will work in February — than any map of the village.
Furnace Direct installs licensed recovery ventilators in Marine on St. Croix and the river parcels above and below the village. No equipment is sold here. The lot read exists because on steep ground the route and the terminations are most of what makes an install good or bad.
Usually a north or northeast band against the house, often behind a shrub line or under a steep bank. It marks the coldest, least-sunned, slowest-drying ground on the parcel. Whatever wall faces that strip is the wall where frost will form at a termination hood, where an intake screen will ice first, and where exterior condensation will linger longest. On a river lot the strip is frequently also the narrowest, which is exactly why it keeps getting proposed as a termination wall and exactly why we would rather not use it.
Cold air drains downhill and pools at the bottom. On the lanes stepping toward the water, the low end of a drive can sit several degrees colder than the top on a still night, and that is where melt refreezes first. It tells you the parcel has genuine cold-air drainage, which affects where a low termination would sit in a pocket of the coldest air available and how much frost management the unit will be doing in deep winter.
This is the only record on the list that is reporting on the inside of the building. A repeating dam at the same stretch of eave means warm indoor air is reaching the roof deck there — an unsealed ceiling plane, a bath fan dumping into a soffit, or a chase that was never closed. That matters for ventilation because it is the same leak path that has been doing your air exchange by accident, and sealing it is usually a prerequisite rather than an alternative.
Valley fog settles in the low ground and sits. Parcels inside the fog line see more frequent high outdoor humidity in the shoulder seasons and heavier dew on everything that faces the water. That changes intake screen maintenance, hood selection, and how often you will be wiping something down. It is a real difference between a house on the flats and one up on the bluff shelf, and it is worth naming on a quote.
A wall that never dries is a wall with deep shade, poor air movement, and often a grade or gutter problem feeding it. We avoid putting intakes there, because the air at that wall is the dampest and dirtiest on the parcel, and because servicing a hood on a face you cannot easily reach with a ladder in February is a problem you inherit. On the National Register blocks it also tends to be the elevation with the least room to work.
Four of the five are measuring the same two variables in different units: how much sun and wind a given face gets, and where cold air collects when the air is still. Those two variables set the surface temperatures at your terminations, which sets how much frost the unit manages in deep winter, which sets where we want the intake and how we detail it. The fifth, the ice dam, is the odd one out — it is an indoor measurement that happens to be legible from the driveway, and it is often the most useful single observation on the parcel because it points at the leak that has been ventilating the house by accident.
| Loudest sign outside | What the house is doing inside | How we read the pair |
|---|---|---|
| Cold-air pooling at the bottom of the drive, long-lasting north snow strip | Glass clear even on the coldest mornings; floor seams opened this winter | Energy-recovery lean. The lot is telling us the exterior is harsh, and the house is telling us it cannot hold moisture. Keep what little vapor the household makes and terminate away from the cold pocket. |
| Repeating ice dam at the same eave, fog line above the house | Beaded or filmed glass on two different walls at dawn | Heat-recovery lean, with the ceiling plane sealed first. The dam and the wet glass are the same story: moist indoor air finding cold surfaces and leak paths. Air-sealing comes before any appliance is commissioned. |
| Green north wall, deep shade, parcel inside the fog line | Lower level damp in late summer, upper floor static in January | Two climates. This is the split-house pattern and it is common on stepped river lots. One cabinet can serve both, but the balance and damper design is the real work, and it gets decided on site. |
| Wind-scoured corner where snow never accumulates | Complaint changes from week to week with no pattern | Measure before deciding. A heavily wind-exposed elevation plus unstable indoor readings usually means infiltration is still doing a lot of uncontrolled work, and the honest next step is a blower-door number rather than an appliance. |
A parcel in the fog line with a cold-draining drive and a green north wall still gets whichever core its indoor winter behaviour calls for. If anyone tells you a river lot, a bluff shelf, or proximity to open water selects the technology, ask them which indoor reading they are relying on — because that reading is the whole decision. What the lot genuinely decides is where two hoods can live, how they are flashed and screened, how often you will clear debris from them, and whether a crew can safely work the elevation we would otherwise prefer.
Walked the parcel? One lot sign and one window reading is enough to start.
Turn the walk into a quoteStand at the top of the drive and look down at the house. Note how much the grade falls between the front door and the lowest corner, because that number tells us how far a wall that is reachable at the front has climbed by the time it reaches the back. Then note which elevation you could put a ladder on with snow on the ground and a hand on something solid — on the steepest parcels in the village there is exactly one, and it may not be the one closest to the mechanical room. That single fact sets the duct length, the number of framing bays we open, and the shape of the whole day. It is worth more to a scope than any other sentence you can send us.
Plain words beat labels. "North strip holds snow until April, drive glazes at the bottom, fog sits below the house most autumn mornings, ice ridge over the kitchen eave every January" is a complete lot record and it took one walk. Add the indoor reading — one window, one dawn, one outdoor temperature — and we can usually name a core lean, a preferred termination elevation, and the parts of the day likely to run long before anyone drives out.
No, and we would be suspicious of anyone who said it did. The lot record changes termination siting, frost management, screen maintenance, hood selection, and how a crew stages a steep driveway in February. The core is chosen from what the air inside the house does in deep winter. The point of reading the lot is that it makes the install right, and it tells you which indoor readings to trust.
Because the parcel is where the ventilator gets installed. Two houses on the same lane, one up on the shelf and one down in the low ground, will differ more from each other than either differs from a house across the river. Village-scale descriptions average exactly the detail that decides where a hood can go.
It can restrict what is visible from the street and how penetrations are detailed on a protected elevation, so we plan terminations on secondary faces wherever the mechanics allow. That is a routing and detailing conversation. Nothing about it changes the airflow the house needs or which core suits it.
Then that is the single most important line in your scope. Safe ladder footing and snow clearance determine which elevation can hold two terminations, and on the steepest parcels there is exactly one answer. Sometimes we run more interior duct to reach a wall we can service, and that trade belongs in the quote rather than in a surprise on install day.
Usually yes, and not only for the roof's sake. A repeating dam means warm moist indoor air is reaching the roof deck, which is simultaneously a moisture problem, an energy problem, and the accidental ventilation path the house has been relying on. Seal it, then ventilate deliberately. Doing it the other way around leaves the leak in place and the complaint half-solved.
The north and the sheltered elevations at grade, the drive from the top looking down, the eave where ice forms, and the mechanical room wide enough to show clearances. If the parcel has retaining walls or a bank close to the house, include those. That set lets us plan a route and a staging approach without guessing.
The loudest sign outside, one dawn observation inside, and how the grade falls. A core lean and a flat installed price come back.
These pages never go outside. They choose the core from matchups, materials, ownership history, and what the old cabinet is doing.