Commercial Ventilation
Make-Up Air Unit Service
Grande Prairie
A make-up air unit replaces the air your exhaust system pulls out of the building. Kitchen hoods, vehicle exhaust fans, welding extraction and dust collection can move thousands of CFM out through the roof, and every cubic foot has to come back in from somewhere. When the MUA stops delivering tempered air, the building goes negative and everything downstream starts to misbehave.
We repair, maintain, replace and install make-up air units for commercial and industrial buildings across the Peace Country.
How It Works
Building Pressurization And Tempered Outdoor Air
Every exhaust fan in a building is a pump moving air outdoors. A commercial kitchen hood, a vehicle exhaust reel in a truck shop, a paint booth, a welding extraction arm or a dust collector can each move hundreds to thousands of CFM. Air is not compressible in any useful way at building pressures, so whatever leaves has to be replaced. A make-up air unit is the piece of equipment that replaces it on purpose, drawing in 100% outdoor air, heating it to a controlled discharge temperature, and delivering it near the exhaust so the building stays close to neutral.
Without that supply, the building finds its own make-up air through whatever leaks it can find. That is when the familiar symptoms show up: exterior doors that are hard to pull open, wind whistling through the seals, cold air sheeting across the floor at the entrance, a furnace or water heater backdrafting down its flue, and a kitchen hood that stops capturing smoke because it is starved. Matching supply CFM to exhaust CFM is the whole job, and it is why ASHRAE 62.1 and the ventilation requirements of the Alberta Building Code treat make-up air as part of the exhaust design rather than an accessory to it.
A make-up air unit is not the same equipment as a rooftop packaged unit. An RTU mostly recirculates and conditions building air with a modest outdoor-air fraction, while an MUA heats 100% outdoor air on its way in. Many Grande Prairie buildings run both, and if the packaged units on your roof also need attention our rooftop unit service covers those. Make-up air service sits inside our broader commercial HVAC work, which matters here because at -40 °C an MUA may be raising incoming air by 55 °C or more before it ever reaches the space.
Why Choose Us
Why Choose Indoor Elements For Make-Up Air Unit Repair
Make-up air units sit at the intersection of gas, airflow, controls and code, and plenty of contractors would rather not open one. We have been working on them in restaurants, shops and plants across the region since 1991, alongside the rest of the heating and ventilation equipment in those buildings.
What We Handle
Make-Up Air Problems We Fix
These are the faults we are called out for most often on MUA units in Grande Prairie, and what is usually behind them.
Unit Won't Fire Or Locks Out On Flame Failure
A make-up air unit that will not light is usually being stopped by a safety, not by the burner itself. Air-proving switches that never make, high or low gas pressure switches that have tripped, a dirty flame rod, a failed ignition control or a spark electrode out of position will all hold the burner off. We work through the sequence of operation in order rather than swapping parts, so the reason for the lockout gets found and corrected.
Discharge Air Too Cold Or No Heat At All
If the blower runs but the air coming through the diffusers is cold, the unit is doing half its job and pulling your building temperature down with it. Modulating gas valves that will not open past minimum, a failed discharge air sensor, incorrect manifold pressure, a plugged burner or a cracked heat exchanger on an indirect-fired unit all show up as a discharge temperature that never reaches setpoint.
Tripping On High Limit Or Freeze Stat
High limits and freeze stats trip for a reason, and the reason is almost always airflow. Plugged filters, a slipping belt, a damper that is only partly open, blocked intake screens or a burner firing above design rate will all push temperatures past the safety setpoint. Resetting the switch without finding the cause just moves the shutdown to the next cold night.
Intake Damper Not Opening
The intake damper has to be proven open before the burner is allowed to fire. Seized linkage, a failed actuator, a broken end switch, ice buildup on the blades or a control signal that never arrives will leave the unit either locked out or, worse, pulling air through a partly closed damper. We service and replace damper actuators and rebuild the linkage so the blade travels its full stroke.
Plugged Intake Filters And Restricted Airflow
A make-up air unit takes 100% outdoor air, so its filters see everything the Grande Prairie air carries. Spring poplar fluff can blanket an intake in days, and gravel-lot dust does steady damage all summer. Restricted filters starve the burner, drop delivered CFM, drive up static pressure and are the single most common cause of nuisance high-limit trips we find.
The Building Is Going Negative
Doors that are hard to pull open, wind whistling through door seals, a furnace or water heater that backdrafts, cold drafts across the floor and a kitchen hood that no longer captures smoke are all symptoms of one problem: more air leaving the building than coming in. We measure exhaust CFM against actual make-up air delivery and building pressure, then correct the imbalance rather than guessing at it.
Blower, Belt And Bearing Noise
Rumbling, squealing or a new vibration from the unit usually means the mechanical side needs attention. Worn belts, misaligned or worn sheaves, dry bearings, a fan wheel that has picked up dirt and gone out of balance, or loose isolation feet all get worse and eventually take out the motor or the shaft. We replace belts and bearings, align and set sheaves, and balance airflow again after the repair.
Control And Sensor Faults
Modern make-up air units run on a control board reading a discharge air sensor, an outdoor sensor, proving switches and often a building automation input. A drifting sensor, a corroded terminal, a failed board or a lost interlock signal produces behaviour that looks mechanical but is not. We read the fault codes, verify the sensors against actual measured temperatures, and repair the control problem at its source.
Equipment Selection
Choosing The Right Make-Up Air Unit
Three decisions determine how a make-up air unit performs: how it heats, how much air it moves, and how it is controlled and interlocked. Shops that need ventilation and spot heat often pair an MUA with radiant tube heaters, and we plan both together.
Direct-Fired, Indirect-Fired Or Electric
A direct-fired unit fires its burner straight into the airstream, so close to all the fuel energy reaches the space. It handles the big temperature rises our winters demand, and it suits shops, warehouses and industrial bays with high exhaust volumes and good dilution. An indirect-fired unit burns inside a heat exchanger and vents combustion products outside, which is the right call where products of combustion cannot be introduced or the process is sensitive. Electric make-up air avoids gas entirely and fits smaller volumes or buildings without adequate gas service.
Sizing, CFM And Building Pressure
Sizing a make-up air unit starts with the exhaust, not the floor area. We add up hood, process and general exhaust CFM, then size supply to leave the building very slightly positive so doors work and infiltration stays under control. Heating capacity follows from that airflow and the design temperature rise, which in the Peace Country means tempering air from -40 °C. Getting this wrong in either direction is expensive: undersized leaves the building negative, oversized wastes gas and overpressurizes the space.
Controls, Interlocks And Code Compliance
Discharge-air temperature control, modulating gas valves, VFDs or ECM blowers for two-speed operation, and interlocks with the exhaust fan all decide how the unit behaves day to day. In a commercial kitchen the MUA also has to shut down with the fire suppression system, a requirement that flows from NFPA 96. Gas piping and appliance installation follow CSA B149.1, and certified direct gas-fired heaters carry ANSI Z83.4 / CSA 3.7 listing. We wire and commission to those requirements so the unit passes inspection the first time.
Our Process
From Diagnosis To Commissioning
Whether we are chasing a lockout on an existing unit or setting a new one on a curb, the work follows the same four steps. Nothing gets called finished until the numbers say it is.
Site Assessment And Diagnosis
We measure rather than assume. That means delivered airflow and static pressure, exhaust CFM from every hood and fan, building pressure relative to outdoors, incoming and manifold gas pressure, discharge air temperature against setpoint, and the full sequence of operation through every safety and interlock. On gas-fired units we run a combustion analysis and test for CO.
Repair Or Replacement Plan And Written Quote
You get findings in plain language and a written quote before work starts. On an older unit we lay out honestly what a rebuild buys you and where parts availability is heading, so you can weigh repairing what is there against replacing it with equipment sized to your current exhaust load rather than the load the building had twenty years ago.
Repair Or Installation
Repairs cover burners and gas trains, ignition controls, pressure and proving switches, high limits and freeze stats, damper actuators and linkage, blowers, belts, sheaves and bearings, sensors and boards. Replacements include crane work, roof curb or curb adapter, gas piping, electrical, ductwork connections and control wiring, including the interlocks to your exhaust fans and fire suppression system.
Commissioning, Permits And Inspection
Commissioning is where a make-up air unit is actually made to work. We set the burner profile and manifold pressure, verify discharge air temperature control across the firing range, confirm airflow and building pressure with the exhaust running, pressure test the gas piping, run a final combustion analysis with CO testing, and prove every safety and interlock. We pull the Alberta permits and book the inspections.
Maintenance And Emergency Support
Make-up air units reward attention and punish neglect. Because they handle 100% outdoor air, their filters load faster than anything else in the building, and a plugged intake is the first domino in most of the failures on this page. A scheduled commercial maintenance program puts filter changes, belt and bearing checks, damper travel, burner inspection, safety testing and airflow verification on the calendar, timed around the seasons that cause trouble here: poplar fluff in spring, dust through summer, and a full inspection before the first hard freeze.
When something does fail in the middle of a cold snap, the clock matters. A unit stuck pushing untempered air into a building will pull indoor temperatures down fast and put plumbing on exterior walls at risk, and a kitchen without make-up air cannot run its hood properly. Our 24/7 emergency HVAC service covers make-up air units the same way it covers heating, so you are never waiting until Monday to get a shop or a restaurant back in operation.
Trust & Experience
Grande Prairie's Trusted MUA Unit Contractor
Restaurants, vehicle and heavy-equipment shops, paint booths, welding and fabrication shops, warehouses, manufacturing plants, oilfield service shops and arenas across Grande Prairie all depend on make-up air they rarely think about until it stops. We have been the people those buildings call since 1991, and we treat a make-up air unit as part of a ventilation system rather than a box on the roof.
That approach matters because the fix is often not where the complaint is. A hood that stops capturing is rarely a hood problem. A door nobody can open is rarely a door problem. We measure the whole picture, tell you what we found, and correct the cause.
Family-Owned Since 1991
More than 30 years of commercial and industrial mechanical work in the Peace Country, including make-up air units on kitchens, shops and plants of every size and vintage.
Built For This Climate
We size and commission make-up air for -40 °C intake temperatures, winter door-open cycles at loading bays, and the spring poplar fluff that blankets intake filters across Grande Prairie every May.
Licensed, Insured, WCB And COR Certified
Licensed Alberta gas fitters and refrigeration and sheet-metal trades on staff, full liability insurance, WCB coverage and COR certification, with fall protection training for rooftop work.
What Our Commercial Customers Say
Trusted by Grande Prairie Businesses
“During the estimate process I felt all my questions and concerns were heard and addressed. All 3 techs that came on site were efficient and knowledgeable of the job to be done. Very respectful of our home. So appreciative to have A/C”
Lorna Sheehan
August 2026
“Fantastic to collaborate with Indoor Elements for a whole home back up generator installation along side our grid tied solar system project. They handled their end of the deal in a efficient professional manner. From the owner to the office to the field techs, everyone was a pleasure to work with an hope to partner again on projects moving forward.”
Chris Jacobson
August 2026
“The service technician did a great job . He quickly found the issue and while completing the repair was able to answer any questions I had. Also before leaving left me with a few “good to knows” quick tips which is much appreciated. We have used Indoor Elements before and will definitely use them again.”
lawrence turick
July 2026
“Indoor elements installed a new high efficiency furnace and heat pump in our home. From coming and doing the estimate to final checks, they were professional, friendly and efficient. Luke was very thorough in providing an accurate estimate of our needs and broke things down in three easy to understand options to consider. All four installers produced a clean, organized final product. Now we just need some warm summer days so we can fully enjoy our newly air conditioned home.”
Kevin Bain
June 2026
“Exceptional work. Always professional. Gives me peace of mind knowing all my systems are looked after. I always recommend indoor elements”
Dan Student
June 2026
“The team from Indoor Elements are well skilled in their chosen field, are always on time, and will answer any questions. I would recommend them.”
Janeen. Knapp
May 2026
“They answer your call right away and the service was great.”
sam dayo
May 2026
“Recently had a furnace installed by indoor elements after having furnace issues, their prices were very competitive compared with other venders in the city, They were very knowledgeable and did a great job installing everything and were very professional the entire time and answered all my questions and then some. Would recommend them for all your furnace and Machanic needs. Happy with the service provided so far. EDIT had them instal my AC system and again service was great and install was great , I had a bit of a challenging install due to the furnace room location, but still was able to make it work no problem. The install was alot cleaner then compeditors installs I had done in other houses, and more attention to detail was taken.”
Tyler M
May 2026
“Fast and reliable service!”
Shirley McKeever
April 2026
Service Coverage
We Come to You
We service, repair and install make-up air units throughout Grande Prairie and the surrounding Peace Country, with the crane and rigging arrangements a rooftop unit change-out needs.
Grande Prairie — restaurants and commercial kitchens downtown and along the retail corridors, plus the industrial parks on the city's edges
County & Rural — oilfield service yards, heavy-equipment shops and shop buildings throughout the County of Grande Prairie
Peace Country — Clairmont, Sexsmith, Wembley, Beaverlodge and the surrounding communities
Every building type with exhaust — kitchens, paint booths, welding and fabrication shops, warehouses, manufacturing and arenas
Keep The Air Balanced
Get Your Make-Up Air Unit Working Properly
Whether your MUA is locked out, blowing cold, or simply not keeping up with the exhaust it was built to replace, we will measure it, tell you what we find, and fix it. Repair, maintenance, replacement and new installation across Grande Prairie.
FAQ