Heating a house is a solved problem. Heating 40,000 square feet with 24-foot ceilings, four overhead doors that open all day, and a welding bay in the corner is not. We get called into a lot of Southeast Michigan warehouses and shops where the heat was sized for a different use of the building, or was installed for a building that has since been added onto twice, and the result is the same: cold people near the doors, wasted gas, and a heating bill nobody can explain. Here is how the realistic options compare and where each one belongs.
Quick answer
Gas-fired unit heaters cost the least to install, recover temperature quickly, and suit enclosed spaces with moderate ceiling heights. Radiant tube heaters warm people, floors, and equipment directly instead of heating the air, which makes them the stronger choice for high ceilings, frequently opened overhead doors, and spot-heating specific work areas. Many Michigan facilities end up with a combination: radiant over docks and assembly areas, unit heaters in enclosed rooms, and separate equipment for offices.
Why industrial space is hard to heat in this climate
Our heating season runs from roughly October into April, which is a long time to be paying to heat a large volume of air. Three things work against you the whole time. Overhead doors dump heated air every time they open, and in a busy dock that can be most of the day. Tall ceilings encourage stratification, so the warmest air in the building collects fifteen feet above anyone's head where it does no good at all. And industrial buildings often have uninsulated slabs, older wall panels, and gaps around doors that let cold air in continuously.
Add process exhaust to that, from welding, paint, coolant mist, or a spray booth, and you have air being pulled out of the building on purpose as well, often alongside a process cooling system rejecting heat somewhere else in the building. Every one of those factors changes which heating approach makes sense, which is why two buildings of identical square footage can need completely different systems.
Gas-fired unit heaters
A unit heater is the familiar box hung from the ceiling or a bracket, with a gas burner, a heat exchanger, and a fan that blows warmed air out across the space. They are the default in most shops for good reason: they cost the least to install, they are simple to service, parts are available everywhere, and they bring a cold building up to temperature quickly.
The limitations follow from how they work. They heat air, and heated air rises, so a portion of the output ends up at the ceiling. Every time an overhead door opens, much of what you just paid for leaves with it and the space has to be reheated from scratch. They also create air movement, which people notice as a draft, and they can stir up dust in environments where that matters.
One detail worth specifying: separated-combustion units draw combustion air from outdoors rather than from the space. In a dusty shop, a building with any negative pressure, or anywhere with airborne contaminants, that is the right choice and it is worth the difference in cost.
Radiant tube heaters
A radiant tube heater burns gas at one end of a long steel tube and pulls the combustion gases down its length, while a reflector above directs infrared energy downward. It does not heat the air on its way to you. It warms the floor, the equipment, the inventory, and the people, the same way sunlight feels warm on a cold clear day.
That distinction is why radiant works so well in buildings with doors that open constantly. When a door opens, the air changes but the concrete slab, the racking, and the machinery are still warm, so the space feels normal again almost immediately rather than needing to be reheated. It also means people are comfortable at a lower air temperature, and there is far less stratification, because you are not relying on warm air to carry the heat.
Manufacturers commonly claim energy savings in the range of twenty to fifty percent compared with forced-air heating in the right application. Treat those figures as what they are: manufacturer claims under favorable conditions. Real savings depend on your ceiling height, door traffic, insulation, and how the system is laid out, and we would rather run the numbers for your building than quote someone else's brochure.
The tradeoffs are real. Installed cost is higher. Radiant tubes need adequate mounting height and specific clearances to combustibles, which rules them out of some low-ceiling or heavily racked spaces. And layout matters enormously, because radiant energy travels in straight lines, so anything in the way blocks it.
Choosing between them
Start with ceiling height and door traffic, because those two answer most of the question. High ceilings and doors opening frequently point toward radiant. Moderate ceilings in an enclosed space that stays closed point toward unit heaters.
Then look at how the building is used. If people work at fixed stations, radiant aimed at those stations delivers comfort exactly where it is needed and lets the rest of the building run cooler. If the space is mostly unoccupied storage that needs to stay above freezing, unit heaters are usually the economical answer. If you have tall racking, mezzanines, cranes, or low obstructions, take a hard look at what would actually block the radiant path before committing.
Most of the facilities we work in end up mixed. Radiant over the dock and the assembly floor, unit heaters in the enclosed tool room and the back storage area, and a rooftop unit or split system handling the front offices where people expect house-like comfort.
Ventilation, combustion air, and the things that get skipped
Heating equipment is half the conversation in an industrial building. If you exhaust air for welding fume, paint, or any process, that volume has to be replaced, and if it is not, the building goes negative, doors get hard to open, and heaters can be affected. Make-up air units are the answer, and in our climate they need a heat section so you are not injecting 10°F air into an occupied space.
The heaters themselves need combustion air, and in a tighter building or one already under negative pressure, that is a safety matter rather than a performance one. Propane forklifts add carbon monoxide to the equation, and any building running them indoors should have monitoring, not just detectors in an office.
None of this is exotic, but it is routinely left out when heating is quoted as equipment alone. We would rather raise it early than find it during startup.
The cheap fixes that often beat new equipment
Before quoting a system, we look at what the building is losing. Weather stripping and seals on overhead doors, dock seals and shelters, and repairing the gaps around door tracks frequently cut heating cost more per dollar spent than any equipment change. Air curtains at high-traffic doors help where doors cannot stay closed.
Destratification fans are the other one. In a tall building with unit heaters, a great deal of your heat is sitting at the ceiling. High-volume low-speed fans running slowly push that air back down and can make an existing system noticeably more effective without replacing anything. On more than one occasion we have solved a building's comfort complaint with door seals and fans and left the heaters alone.
Sizing and layout mistakes we see repeatedly
Heaters sized for the building as it was before an addition, or before a process exhaust system was added, so the heat can never keep up in January. Unit heaters aimed at overhead doors, which feels intuitive and mostly heats the outdoors. Thermostats mounted on exterior walls, in the path of a heater, or right next to a door, all of which give false readings and cause short cycling. Radiant tubes installed and then blocked when new racking went in. And a single thermostat controlling a building whose dock, production floor, and storage area have nothing in common.
Two practical checks before any retrofit: confirm the gas service and piping can actually carry the load you are adding, because upsizing a meter or a main takes lead time, and confirm the structure can carry the equipment where you intend to hang it.
Planning the work around production
The best time to change out industrial heating is spring and summer, when the building does not need it and the work can proceed in phases without shutting anything down. That is also when equipment lead times are shorter and schedules are more flexible.
We plan industrial mechanical work around your production schedule rather than the other way around, including evening and weekend work where it makes sense, because a facility that cannot stop cannot stop for us either. Permits, inspections, and gas utility coordination all get built into that schedule at the start rather than discovered halfway through.
Frequently Asked Questions
Is radiant tube heating better than unit heaters for a warehouse?
It depends on the building. Radiant is generally better where ceilings are high, overhead doors open frequently, or specific work areas need to be comfortable. Unit heaters are usually the better value in enclosed spaces with moderate ceilings that stay closed, and in storage areas that only need to stay above freezing.
How much can radiant heating save compared with forced air?
Manufacturers commonly cite twenty to fifty percent in favorable applications. Actual savings depend on ceiling height, door traffic, insulation, and system layout, so the honest answer for any specific building comes from a load calculation rather than a published range.
What ceiling height do radiant tube heaters need?
Radiant tubes require specific minimum mounting heights and clearances to combustibles that vary by model and output. Low ceilings, heavy racking, and overhead obstructions can rule them out, which is why layout is reviewed on site before anything is specified.
Do I need make-up air in my shop?
If you exhaust air for welding fume, paint, coolant mist, or any other process, yes. That volume has to be replaced or the building goes negative, which causes doors that are hard to open, drafts, and potential problems with combustion equipment. In Michigan, make-up air units need a heat section to temper incoming winter air.
Can I heat just part of my warehouse?
Yes, and it is often the smart approach. Radiant heaters can be aimed at occupied work areas while surrounding storage space is kept at a lower temperature, and separate zones let you match heating to how each area is actually used rather than heating the whole volume to one setpoint.
When is the best time to replace warehouse heating?
Spring and summer. The building does not need the heat, the work can be phased around production, equipment lead times are generally shorter, and you avoid the risk of a failure during the coldest part of the year.
If your building is cold in the wrong places, or the gas bill has stopped making sense, we can walk the facility, run the load, and lay out the options with real numbers for your building rather than general rules. Kern Mechanical handles large-scale mechanical systems, make-up air, ventilation and exhaust, and process cooling for manufacturing, warehouse, and distribution facilities across Oakland, Livingston, Genesee, Macomb, Wayne, and Washtenaw counties. We are family-owned, licensed and insured, we schedule around your production, and consultations are always free.
Free consultation
Talk to Kern Mechanical LLC
Our family-owned team handles residential, commercial, and industrial HVAC across Southeast Michigan. Quotes are always free.