Cooking Through a Smoke Week: Why a 900-CFM Wolf Hood and a Sealed Seattle House Cannot Both Have Their Way

The call we take most often here

Late every summer the same call arrives: the hood barely pulls, it is louder than it used to be, and the kitchen smells of outside. Owners assume the blower is dying. Usually the blower is fine, and the house has changed the rules on it.

Two things are being asked of the building at once. The kitchen wants a large volume of air removed. The household, quite correctly, wants nothing coming in. Those are not compatible demands, and the hood is where the conflict shows up.

Why this address produces it

Puget Sound now has a recurring late-summer smoke season. In September 2020 wildfire smoke gave Seattle, for several days, some of the worst air quality recorded anywhere in the world, and smoke episodes have returned in later summers often enough that they are a planning assumption rather than a freak year.

The physical conflict is straightforward. A large hood has to take the air it removes back from somewhere, and the only somewhere available is outdoors — through a purpose-built makeup-air path, or through whatever gaps the building envelope still has. The model residential code that Washington adopts asks for makeup air once a hood can exhaust more than 400 CFM.

Now add the housing. Wallingford grew up in the streetcar era, and the craftsman bungalow is still its defining house. Those houses were never built with a dedicated exhaust chase, and for most of their lives their makeup air was simply their own leakage. Ballard’s remodelled craftsman kitchens sit in the same stock, often with the range against an exterior wall. Capitol Hill’s older buildings and tight galley kitchens add a constrained duct route on top. West Seattle’s Alki and Admiral view homes get the wind exposure as well.

The chain, from cause to complaint

Air-seal and insulate one of those bungalows, as many owners have, and the leakage that was quietly feeding the kitchen disappears. Run a large hood in the resulting tight house and it stops exhausting and starts contending with the building. It depressurises the space, airflow collapses, and the motor labours at a duty it cannot satisfy.

That produces the exact complaints on this site’s list. The blower hums but barely pulls smoke off the cooking surface, because it is moving against a house that will not give the air up. The fan trips out partway through a long session, because a labouring motor gets hot and its thermal protection does its job. It rattles and vibrates at the top setting, because a wheel working against high static pressure runs rough.

The smoke-week twist is what happens when the house does give the air up. It arrives through the leakiest remaining paths — a crawlspace hatch, an unused chimney, a bathroom vent — and during an episode those paths are drawing in exactly what you sealed the house against. Worse, if the house depressurises far enough, an atmospherically vented gas appliance can spill combustion products back indoors. That is the reason makeup air is a code requirement rather than a comfort feature.

Ruling out the obvious first

Pull the baffles and wash them. Always first, always free.

Then run the single most informative test there is: crack a window near the kitchen while the hood is on high. If capture suddenly improves and the noise settles, the fault is the house, not the appliance, and no motor replacement will fix it. That one test separates most smoke-season calls into their correct pile within a minute.

If your kitchen has a makeup-air damper, find it and confirm it opens when the hood starts. Interlocks fail quietly, and a closed damper produces symptoms identical to a failing blower.

Then go outside and check the exterior termination and its damper for grease and for a blade that only opens part-way. Then the blower wheel for loading, the run capacitor if the motor hums without moving air, and the speed control if the fan will not stop without pulling the breaker — which is a control fault, not a motor fault.

During an actual smoke episode there is one practical habit worth adopting: run the hood only while you are actively cooking, at the lowest speed that genuinely captures, and prefer cooking methods that produce less smoke and grease. It is not a satisfying answer, but a lower speed that captures beats a high speed that fights the house and pulls outdoor air in behind it.

When it stops being a homeowner job

Makeup air is the line. Sizing and interlocking a makeup-air path in a finished bungalow, or routing a duct through an old wall that has no chase, is design work with a code requirement attached, and it needs to be done properly rather than approximated.

The same goes for anything electrical in the hood. Hood work has no published price band, because blowers, controls and duct runs differ too much between installations; how a hood repair is quoted explains what the $89 visit settles instead. The long roof-ducted hoods over the wide ranges of Laurelhurst are where the path, not the motor, is so often the answer.

Ring (206) 339-4211 if you would rather describe it than type it, and mention whether opening a window changes anything: that one observation usually tells us which half of the problem we are being called to.

Still asked on the phone

Should I use my range hood during a Seattle smoke episode?

Use it while you are actively cooking, at the lowest speed that actually captures. A hood has to replace the air it removes, so running a large one flat out in a sealed house draws outdoor air in through whatever gaps remain. Cooking in a way that produces less smoke and grease, and shutting the hood off promptly afterwards, keeps the kitchen clear without pulling a smoke-season atmosphere through the building.

Why did my hood get worse after we insulated and air-sealed the house?

Because its makeup air was your leakage. Older Seattle bungalows fed a kitchen hood through the gaps in the envelope, and sealing those removes the supply. The hood then works against the house instead of exhausting it: airflow collapses, the motor labours and it gets louder without getting more effective. The residential code Washington builds on sets a threshold, 400 CFM, above which a kitchen hood needs a makeup-air supply for exactly this reason.

Is it dangerous to run a big hood in a tight house?

It can be, which is why the code addresses it. If a house depressurises far enough, an atmospherically vented gas appliance can spill combustion products back indoors instead of up its flue. That risk rises in a tightly sealed home with a high-output hood and no makeup-air path. If you notice odours or backdrafting when the hood runs, stop using it at that speed and have the makeup-air arrangement assessed.

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