Repair or replace · Hoods
Replacing With a Bigger Hood: The Make-Up Air Question
Short answer
A larger Viking hood takes more air out, and the house has to let that air back in. Washington's residential code asks for make-up air on a hood able to exhaust more than 400 CFM only where a fuel-burning appliance inside the air barrier is neither direct-vent nor mechanically vented. Viking Repair Sammamish repairs the hood you have; the swap is the installer's. Call (425) 610-8986.
- Baffle filter — grease collects on the channels and drains to the bottom
- Blower (ventilator) — the only moving part pulling the air
- Backdraft damper — opens under airflow, falls shut when the fan stops
- Metal duct — smooth and straight is best; every elbow costs draw
- Roof or wall cap — where the air finally leaves the house
- Lights and controls — the lamps and the fan and light switches on the canopy
On the bench
-
We measure draw from the hood you have, on each speed, with clean filters
It tells us whether it is genuinely weak or only choked
So we say whether a repair gives back what you feel is missing.
-
We measure the duct size and run behind the current hood
It tells us what a larger ventilator would have to push against
So we flag a small duct before a bigger hood is ordered.
-
We measure the model of the hood and ventilator now fitted
It tells us what airflow the kitchen already lives with
So we compare like with like when a larger unit is on the table.
Every cubic foot out comes back in
Air a hood sends outside is replaced by air drawn in from somewhere else in the house. Viking’s installation guide for its professional wall hoods warns that fuel-burning equipment needs enough air to burn and to clear its flue without back drafting, and it tells installers to check local codes for any make-up air requirement. The larger the hood, the more that warning matters.
What Washington’s code asks
Section M1503.6 of the Washington State Residential Code, 2021 edition, turns on one condition: a gas, oil or solid-fuel appliance inside the dwelling’s air barrier that is neither direct-vent nor vented by a fan. Where one exists, each exhaust able to move more than 400 CFM needs make-up air at roughly the same rate, delivered to the kitchen or a space openly connected to it, through a damper that opens by itself whenever the hood runs. How that reads for a particular house is for the City of Sammamish permit desk to decide.
Viking’s accessories, and where we stop
Viking lists 6-inch and 8-inch universal make-up air dampers, the G6MD and G8MD, among the optional accessories for its 5 Series wall hoods, with separate instructions for an air damper and pressure switch. Choosing and fitting one belongs to the installer and the permit. Our part comes first: telling you whether the hood you have is short on capacity or only short on repair.
Repair or replace: the signs
Repair it when
- The hood you have is weak because of loaded filters, a sticking damper or a tired ventilator
- The canopy and the duct are sound and the only complaint is performance
Replace it when
- The cooking top below is gaining a gas char-grill, which Viking pairs with a 1,200 CFM ventilator
- The hood is damaged past repair and a larger one is planned anyway
Verdict Restore the hood you have if it can do the job. If a bigger one is coming, settle make-up air with the installer and the permit desk before it is ordered.
What it costs here
- Diagnosis visit $89
- Repair of the hood you have now quoted after the diagnosis
$89 buys the visit and the full diagnosis. Go ahead with the repair and that $89 is taken off its price. The replacement side is not priced on this page: it depends on the unit you choose and who installs it.
Asked about this
Does every Viking hood over 400 CFM need make-up air in Sammamish?
Not automatically. Washington's code ties the 400 CFM figure to a condition: a fuel-burning appliance inside the air barrier that is neither direct-vent nor mechanically vented. The City of Sammamish permit desk decides how that applies. Viking Repair Sammamish can check how your present hood performs, (425) 610-8986.
