Why does my kitchen get cold when the hood is on in winter?

Because the hood is pulling a great deal of air out of the building, and that air is replaced as fast as it leaves. If the make-up air unit is delivering it warm, nobody notices. If it is not keeping up, the replacement comes in cold, either through the supply or through every door and gap in the building. Which of those is happening, and why, is something we establish with readings at the unit and in the building rather than guess at from the kitchen.

Can I turn the make-up air unit off in winter to stop the cold draft?

We would rather you did not. The exhaust keeps pulling air out whether the make-up air unit runs or not, so switching it off does not stop cold air coming in. It moves the cold air to the doors and gaps instead, and leaves the building straining against its own hood and against anything that vents through a flue. If the supply is blowing cold, that is the thing to have looked at.

What is the difference between a direct-fired and an indirect-fired make-up air unit?

In a direct-fired unit the gas burner sits in the airstream and heats the air directly, so the products of combustion go into the building with the supply air. That is why those units carry safeties tied to airflow and are used where the codes in force allow them. In an indirect-fired unit the burner fires into a heat exchanger and vents through a flue, much like a furnace, so the supply air never touches the flame. Your unit’s nameplate says which it is.

How often should a make-up air unit be serviced?

At least once a year, timed before the heating season, and more often where the exhaust runs long hours. We work on quarterly, semi-annual and annual schedules, and the right one depends on the building — how hard the hood or extraction runs, what the unit is serving, and what a cold or out-of-balance building costs you on a busy day.

Does hood cleaning cover the make-up air unit?

Usually not. Hood cleaning is about the exhaust side: the hood, its filters, the duct and the exhaust fan. The make-up air unit is the supply side, and on most kitchens it is a gas-fired heating appliance with its own burner, controls and safeties. It is serviced as a separate piece of equipment, and it is worth asking who looks after it if nobody has.

Do you work on make-up air units you did not install?

Yes. We work on all makes and models, on kitchens, shops, paint booths and anything else running serious exhaust across Wichita and South Central Kansas. If yours has stopped keeping the building comfortable, we find out why before recommending anything.

Make-Up Air

Make-Up Air Units in Winter: What Wichita Kitchens and Shops Should Know

Every cubic foot of air a hood or an extraction fan pulls out of a building comes back in somewhere, and in a Kansas January the only question is whether it comes back heated, through the make-up air unit, or cold, through every door and gap in the place.

Published: October 4, 2026
Reading time: 12 min read
Category: Make-Up Air

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A make-up air unit in winter has a harder job than at any other time of year. In July it only has to put back the air your hood, your welding extraction or your paint booth is pulling out. In January it has to put that air back warm, and the gap between the air outside and the room it is going into is the widest it will be all year.

Most owners never think about the unit until it falls behind. The line gets cold every time the hood comes on, the back door fights you, or somebody finds the switch that stops the cold blast and leaves it off — which feels like a fix and is not one.

This is written for Wichita-area restaurant owners, kitchen managers and shop owners heading into the cold months. It covers what the unit is doing, what a building out of balance feels like, why South Central Kansas weather is hard on the heating side, what you can check yourself, and what a technician measures.

What a make-up air unit does in winter

A building can only push out as much air as it lets in. A kitchen hood, a welding fume extractor or a paint booth exhaust fan moves a great deal of air outdoors, far more than ordinary heating and cooling equipment is built to replace. The make-up air unit is the machine that brings that air back: a fan, a filter, a set of dampers and, in a cold climate, a heater, usually on the roof or on a stand beside the building.

In winter the heater is the whole story. Outdoor air drawn into a kitchen in January is the coldest air the building will see, and the unit’s job is to warm it on the way in so the people standing under the supply never notice it arriving. Most heated units are gas-fired; some run a hot-water coil off a boiler, and some use electric heat.

The unit is also tied to the exhaust it serves. In most installations the two are interlocked, so turning the hood on calls the make-up air unit on with it. That pairing is the reason a make-up air unit gets blamed for a cold kitchen and switched off, and the reason switching it off makes a different problem.

A make-up air unit on a steel stand outside a commercial building, its sloped intake hood on one end and galvanized supply duct running into the wall — A make-up air unit on a stand outside a building: intake hood at one end, supply duct into the wall at the other. In winter, everything that comes through that hood has to be warmed before it reaches the room.

What a building does when the make-up air falls behind

The exhaust does not stop pulling because the make-up air unit has stopped keeping up. The air it removes is replaced anyway, through whatever opening is easiest: under doors, around windows, down a flue, through the gap above the ceiling. The building goes negative, and in winter every one of those openings is letting in outdoor air nobody has warmed.

What that looks like depends on what the building is for.

In a commercial kitchen

The cooks feel it first: a cold draft along the line whenever the hood runs, or a blast of cold air from the supply when the heat is not keeping pace. Front-of-house feels it next, at the entrance door that whistles or pulls hard against the people trying to open it.

The hood itself can stop clearing smoke and steam the way it used to, because it is now competing with the building for air. And gas cooking equipment, water heaters and other appliances that vent through a flue are designed to do so in a building that is not straining against them. When any of that starts, it is worth a call rather than a workaround.

In a shop, a welding bay or a paint booth

In a fabrication shop the extraction that keeps fumes off the floor is the same fan pulling cold air in at the overhead door. A unit that is not heating turns the bay nearest the supply into the coldest place in the building, and people start propping doors and unplugging things to make it bearable.

A heated paint booth is a make-up air system in its own right: the booth’s supply heats the air it brings in so the finish goes on and cures the way it should. When that heat falls behind in January, the booth shows it in production before anybody has looked at the burner.

Paint booth maintenance programs and repairs

Why South Central Kansas winters are hard on a make-up air unit

Wichita does not have one kind of winter day, and a make-up air unit feels every kind.

Mild autumns, then the first hard morning

Most of the autumn, the heating section of a make-up air unit barely runs. Then the first genuinely cold morning arrives and it is asked for everything at once, with the hood on high and a full kitchen behind it. A burner, an igniter or a control that has been idle since March gets its first real test on the busiest day of the week. That is the argument for looking at it in October rather than in December.

Big swings inside one day

A South Central Kansas day can start well below freezing and finish mild. The heating side of the unit has to follow that the whole way, giving a lot of heat at seven in the morning and very little by three. How well it tracks depends on how the controls read the air and how the burner adjusts, both of which drift with time and both of which are checked with instruments.

Wind, ice and snow at the intake

The intake hood faces the weather. Wind finds it, drifting snow and freezing rain can build up on it, and the cottonwood fluff of early summer and the leaves of autumn are often still sitting in the filters when winter arrives. An intake that cannot breathe is a unit that cannot keep up, however well the rest of it works.

A pre-winter make-up air checklist for owners

You do not need to open the unit to learn a good deal about it. Most of what is worth knowing before winter can be seen, heard or felt from the kitchen floor, the shop floor or a safe roof access.

Before the cold: what to look for

All of these are worth writing down and mentioning when you call:

The make-up air unit comes on when the hood or the extraction comes on, and goes off when it does.
The air from the supply feels warm on a cold morning once the unit has been running a little while — not just moving.
Exterior doors open and close normally with the exhaust running, and do not whistle, slam or stand open on their own.
The hood still clears smoke and steam the way it did last winter.
Nobody has turned the unit off, unplugged it, or taped over a supply diffuser to stop a draft.
The intake hood is clear of leaves, debris and anything stored against it, and nothing is blocking the louvres.
The filters, if you can see them safely, are not visibly caked or collapsed.
No new squeal, rattle, rumble or burning smell from the unit when it starts.
Pilot lights and burners on cooking equipment behave normally with the hood on, and do not flicker or lift.
Nothing has changed on the exhaust side — a new hood section, a bigger fan, a new piece of cooking or welding equipment — since the unit was last looked at.

Every one of those has more than one possible explanation, and which one applies is measured, not guessed. Tell us what the building is doing and when it started.

If you ever smell gas near the unit or the cooking line, none of this applies. Leave the building and call the gas utility from outside.

What a make-up air unit service visit covers before winter

A pre-season visit is mostly about the heating section, because that is the part that has sat unused all summer and the part the building depends on in January. The fan and filter side gets its share too, because a heater that cannot move air cannot deliver heat.

On a make-up air unit before winter, we are working through:

The burner, the ignition and the flame safeguard — that it lights, proves flame and shuts down when it should.
Gas supply and manifold pressure against the unit’s nameplate.
Combustion and venting on an indirect-fired unit, where the heat exchanger and flue are part of the job.
The discharge temperature control and its sensors, and whether the unit is actually delivering the temperature it is set to.
The interlock with the exhaust: that the hood or extraction calls the unit, and that the unit proves airflow before it fires.
Low-limit and freeze protection, the safeties that keep a unit from blowing untempered air into the building.
Blower, belts, bearings and the motor’s draw against its nameplate.
Filters, intake dampers and their actuators.
How the supply compares with the exhaust it is meant to replace, where the building shows signs of running out of balance.

You hear what we found and what it means before any work starts, including the times the answer is a filter and an adjustment rather than a part.

Make-up air unit maintenance in Wichita

Where it fits in a building’s maintenance year

A make-up air unit is easiest to forget of anything on the roof, because it does its job quietly and nobody sees it. It earns a place on the same schedule as the rest of the building’s equipment, timed so that the heating side is looked at in the autumn, before it carries the winter.

We work on quarterly, semi-annual and annual schedules, and what sets the interval is how hard the exhaust runs and what a cold or out-of-balance building costs the operation. A kitchen running a hood twelve hours a day is a different machine from a shop that welds a few afternoons a week, even if the two units carry the same nameplate.

If the building also has rooftop units, a boiler or walk-in refrigeration, it is worth planning them together. One visit can cover the whole roof, and the same readings that tell us about the make-up air tell us about the equipment working beside it.

Planning a commercial maintenance year in Wichita

Common questions

Why does my kitchen get cold when the hood is on in winter?: Because the hood is pulling a great deal of air out of the building, and that air is replaced as fast as it leaves. If the make-up air unit is delivering it warm, nobody notices. If it is not keeping up, the replacement comes in cold, either through the supply or through every door and gap in the building. Which of those is happening, and why, is something we establish with readings at the unit and in the building rather than guess at from the kitchen.
Can I turn the make-up air unit off in winter to stop the cold draft?: We would rather you did not. The exhaust keeps pulling air out whether the make-up air unit runs or not, so switching it off does not stop cold air coming in. It moves the cold air to the doors and gaps instead, and leaves the building straining against its own hood and against anything that vents through a flue. If the supply is blowing cold, that is the thing to have looked at.
What is the difference between a direct-fired and an indirect-fired make-up air unit?: In a direct-fired unit the gas burner sits in the airstream and heats the air directly, so the products of combustion go into the building with the supply air. That is why those units carry safeties tied to airflow and are used where the codes in force allow them. In an indirect-fired unit the burner fires into a heat exchanger and vents through a flue, much like a furnace, so the supply air never touches the flame. Your unit’s nameplate says which it is.
How often should a make-up air unit be serviced?: At least once a year, timed before the heating season, and more often where the exhaust runs long hours. We work on quarterly, semi-annual and annual schedules, and the right one depends on the building — how hard the hood or extraction runs, what the unit is serving, and what a cold or out-of-balance building costs you on a busy day.
Does hood cleaning cover the make-up air unit?: Usually not. Hood cleaning is about the exhaust side: the hood, its filters, the duct and the exhaust fan. The make-up air unit is the supply side, and on most kitchens it is a gas-fired heating appliance with its own burner, controls and safeties. It is serviced as a separate piece of equipment, and it is worth asking who looks after it if nobody has.
Do you work on make-up air units you did not install?: Yes. We work on all makes and models, on kitchens, shops, paint booths and anything else running serious exhaust across Wichita and South Central Kansas. If yours has stopped keeping the building comfortable, we find out why before recommending anything.

Side by side

Untempered, Direct-Fired or Indirect-Fired?

There are three ways a make-up air unit can deal with winter air, and the first useful thing to know about your own is which one it is. It is written on the nameplate. This is how the three differ in a Kansas winter.

Untempered, Direct-Fired or Indirect-Fired?: Untempered, Direct-fired, Indirect-fired compared on How the incoming air is heated, Where the combustion goes, What a Kansas January feels like with it, Where it is usually found, What a pre-winter visit concentrates on.
Compared on	UntemperedA fan, filters and dampers. No heater.	Direct-firedA gas burner in the airstream heats the air on its way in.	Indirect-firedA burner fires into a heat exchanger; the supply air passes over it.
How the incoming air is heated	UntemperedIt is not. Outdoor air comes in at outdoor temperature.	Direct-firedDirectly, by a burner the supply air passes through.	Indirect-firedIndirectly, across a heat exchanger, the way a furnace heats a house.
Where the combustion goes	UntemperedNowhere. There is no burner.	Direct-firedInto the supply air, which is why these units prove airflow before they fire and carry safeties around it.	Indirect-firedOut through a flue. The supply air never touches the flame.
What a Kansas January feels like with it	UntemperedCold at the supply whenever the exhaust runs, unless something else in the building is heating that air.	Direct-firedWarm supply air whenever the burner is keeping pace, and quick to respond as the weather swings.	Indirect-firedWarm supply air like a direct-fired unit, with a heat exchanger and a flue that both need looking after.
Where it is usually found	UntemperedSpaces where the exhaust runs lightly or briefly, or where the room’s own heating is sized to absorb the incoming air.	Direct-firedKitchens, shops and warehouses replacing large volumes of air, where the codes in force allow it.	Indirect-firedSpaces where combustion products should not go into the supply air.
What a pre-winter visit concentrates on	UntemperedThe fan, belts, filters, dampers and the interlock with the exhaust.	Direct-firedBurner, ignition and flame safeguard, gas pressure, airflow proving, and the discharge temperature control.	Indirect-firedBurner, heat exchanger, flue and venting, combustion, and the controls.

Some heated units use a hot-water coil off a boiler or electric heat instead of a burner. Same job, different equipment, and the same reason to look at it before winter.

Your first and last call

Have the Heat Side Looked At Before the Cold Arrives

A make-up air unit that is going to struggle in January is usually giving something away in October, if anybody is listening for it. If your kitchen or shop anywhere in the Wichita area goes cold, drafty or smoky when the exhaust runs, or you simply do not know when the unit on the roof was last looked at, ring us. The order is the same as on every job of ours: find out what is happening first, then talk about what it needs.

More than twenty years installing and servicing heating and cooling across Wichita and South Central Kansas, residential and commercial, on all makes and models — make-up air units, paint booths, rooftop units, boilers, chillers and walk-in refrigeration among them. Fairly priced, and you know what is involved before any work starts.

Call 316-807-1713 before the first cold morning, not after it.

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