A unit heater is a simple yet versatile solution for heating a wide variety of indoor spaces, such as garages, workshops and storage facilities. It is essentially a box with a fan and a heat-producing element; the fan continuously draws in cool air for the element to heat and blows it out the other side of the unit heater. The self-standing appliance may utilize steam, hot water, propane, natural gas or No. 2 heating oil as its source of energy.

Unit heaters boast many benefits. They are simple to install, in large part because they do not require connection to a ventilation system. They are efficient, especially condensing models which are designed to recover heat they might otherwise have wasted. They can be controlled with a conventional thermostat, provide anywhere from 25,000 to 400,000 BTU/hr, and demand very little maintenance.

But no machine is so well-designed that it requires zero maintenance. Whether you are considering adding a unit heater to your hobby, commercial or industrial space or have already added one, here is what you need to do to increase the appliance’s efficiency and promote safer operation.


  1. Inspect Unit Heater Every Autumn

Your heater will waste fuel and pose a heightened risk of starting a fire if any one of its essential components incurred damage during the summertime. Autumn inspection should include ensuring that:

  • Ventilation system fan and motors are operational
  • Fan blades rotate freely
  • Wiring is connected and properly insulated
  • Gas pipes are not leaking or corroded
  1. Ensure Unit Heater Has Proper Clearance

Even if your unit heater was correctly installed, it is possible that you or your staff placed objects too close to the appliance for safe operation. Depending on its model and size, the bottom of a unit heater must be at least 1″ to 12″ away from any combustible. Likewise, the flue collector must be at least 1″ to 6″ away from any combustible.

It is essential to ensure that the intake and output zones of the unit heater are both unobstructed. Remove any obstacles that could prevent the fan from drawing in a steady supply of cool air or expelling heated air. An improperly stored ladder could easily diminish a unit heater’s efficiency!


  1. Check Manifold Gas Pressure

A unit heater’s manifold connects its burner assembly and gas valve. When the manifold fails to sufficiently pressurize gas, the unit heater will have difficulty igniting and combusting. When the manifold over-pressurizes gas, the heat exchanger can overfire, which will accelerate wear and tear and potentially trigger the unit heater’s automatic shutoff before it has warmed the surrounding area.

The best manifold gas pressure for a natural gas furnace typically ranges between 3.2”WC and 3.7”WC, although your unit heater’s rating plate will likely specify a different amount. Inspect for signs of corrosion and insect infestation while you are checking your gas manifold pressure, and also ensure that all gas connections are fitted properly.


  1. Examine Fan Functionality

Without its fan, a unit heater is essentially a fire in a box – unable to circulate heated air throughout the surrounding area. Inspect your unit heater’s fan to ensure that its motor shaft rotates smoothly and freely, and also that all of its power connections are in place and uncorroded.


  1. Examine Burner Tubes

Like its other components, a unit heater’s burner tubes should be free of corrosion. It is especially important to inspect the burner tubes for signs of rodent nests. A mouse may believe a burner tube is a cozy spot to hang out in during the summer. It will find itself sorely mistaken when the unit heater turns on for the first time in the fall, and the obstruction will severely impact the appliance’s efficiency.


  1. Examine Thermostat

Finally, check to make sure the unit heater’s connected thermostat is clean, connected, and adjusted to the correct setting. Ensure that its wiring is not burned, frayed or corroded as the result of leaking batteries.

If unit heater maintenance sounds like an annual task you would rather not tend to yourself, then we welcome you to contact Haugan Heating and Air Conditioning today. We serve the greater Sioux Falls, SD area for all its residential and commercial heating system installation, repair and maintenance needs, and are standing by to ensure all of your heating appliances remain efficient and safe!