8 HVAC Spare Parts You Should Always Have in Hand When Emergency Strikes

In HVAC, there’s are some keywords that can save you from inefficiency or the terrible fate of downtime.

These words are planning, redundancy, and spare parts. Here’s why …

Planning is an obvious one. Scheduled maintenance, regular inspections, appropriate startup, and shutdowns, etc. allow you to identify poor performance and red flags, and take course correction actions before the situation gets worse. What does worse mean? Your system goes down, your occupants have to leave and all the fingers point at you.

The second one is redundancy, a premise for reliable systems. When a component fails, the system should be able to “pick up the slack” and temporarily compensate for the failure until it’s solved. This is possible by having a system that does not operate at full load, and by using active/passive or standby backup components that do not actively participate within the system during normal operation.

The third one is spare parts.

Every day we receive dozens of calls and e-mails from customers looking for parts, and many times “it’s urgent”, meaning that without that one part, the piece of equipment won’t work as expected or, in a worst-case scenario, won’t work at all.

To make things easier, we’ve put together a list of spare parts that we recommend you always have in hand to spare yourself from trouble.

Parts for Cooling Towers


You may think that having an extra motor is too much of an investment for a part that will be sitting around. It’s not. The motor is the heart of the cooling tower, and you should think about it as an investment, an insurance policy that can save you immediately when your equipment is dying. Believe it not, if your motor is not standard, it can take up to four weeks just to get a new one. Have you ever calculated how much it would cost you to rent a new tower in the last minute? Believe me, you won’t be happy with the numbers.

HVAC parts - cooling tower motor

Gear reducer

If the motor is the heart of a cooling tower, the gear reducer is the brain that keeps production up and running. A gear reducer can fail for 3 reasons:

– Lubrication: lack of lubrification can cause a gear reducer to fail. The lubricant forms a thin film that prevents metal-to-metal contact, which could damage metal surfaces. At least once a year, check your lubricant for contamination.

– Alignment: Misalignment due to incorrect angles or backlash between gear teeth can deform, distort, and bend the teeth. When this happens, the load is unequally balanced on the teeth, generating overload that eventually leads to failure.

– Overload: when a gear reducer is pushed to the limit due to emergency stops, cold starts, heavier loads, etc., failure is expected to occur soon. Once the first signs of failure appear, the damage progresses pretty quickly, and generalized failure is a certainty if immediate corrective actions are neglected.

Having bearing, seals, oil, and even an entire gear reducer available for emergencies is crucial, and it certainly avoids pricey downtime costs.

HVAC parts - cooling tower gear reducer

Midwest Machinery represents Marley cooling towers, an SPX brand.

Parts for Pumps

Seals, gaskets, and O-rings

Pressure, cavitation, temperature, vibration, leakage, and improper installation can lead to pump failure.

Seals contain fluids within a vessel where a rotating shaft passes through a stationary housing. They play a critical role in keeping contaminants out. They can leak or become damaged if you let your pump operate dry, generating friction that can cause thermal shock. They can also get damaged due to vibration and hammering couplings. Seals are exposed to several operating conditions, and if the pump is not working as it should, the seals will be affected.

Gaskets are sheets comprised of gasket paper, rubber, silicone, metal, and fiberglass. O-rings are made of rubber. They both have similar applications since they fill the gaps between surfaces to prevent leakage from the pumps. When two HVAC components do not match perfectly, we can put a gasket or an O-ring between them and compress one against the other, joining the objects more effectively.

Having extra seals, gaskets, and O-rings will give you immediate relief and enable you to keep running the pump, but understanding the root of the problem and fixing it is the best approach to avoid reoccurrence in the future.

HVAC parts - pump gaskets


Pumps use bearings to increase the pressure of the fluid through the piping system. Bearings sometimes fail before their expected replacement period because of static overload, wear, corrosion, lubricant failure, contamination, or overheating. As always, failure risks can be reduced with preventive maintenance, by examining changes in noise, vibration, temperature, and lubrication. Even though pumps signal when something is wrong with the bearings, you never know how much time you have with a bearing that has already started to present issues, and having one in hand will save you some expensive downtime (a lot more than your investment in new bearings!).

HVAC parts - pump bearings

Midwest Machinery represents Armstrong, Patterson, and Wilo pumps.

Parts for Boilers

Hot surface igniters

These are relatively cheap parts, and you surely need to have a spare to avoid a high heating bill. An ignitor that has many on/off cycles regardless of the reason (over-sized furnace, dirty filter or blower squirrel cage, dirty evaporator coil, improper thermostat, high gas pressure, etc.) can have a significant impact on the bill. A hot surface ignitor must be checked at least every 4000 hours of operation to evaluate continuity through a multimeter. If the igniter does not present continuity, it is burned and needs to be replaced immediately. Otherwise, the unit will stop working and the valve will just release gas but nothing will happen. It is a simple part to have in hand at all times, and a life-saver.

HVAC parts - boiler igniter

Burner gaskets

If you do not inspect and replace your burner gasket as often as you should because you cannot inspect during service or via fan pressure and need to remove the fan and burner assembly, let me tell you something: it is better to do so than to have to shut down your equipment. Lack of maintenance is the main reason why gaskets fail prematurely. On the other hand, if you inspect your burner once or twice a year, you know that gaskets cannot be reused and that you will have to replace them. One way or the other, you should have gaskets immediately available. They are among the least expensive HVAC parts, and they always come in handy.

HVAC parts - boiler burner gaskets