Heat pumps are relatively quiet under proper operating conditions. However, old, worn, or damaged heat pumps can make all sorts of unwanted noises. Heat pump vibrations should be dealt with as soon as possible to prevent them from worsening. It can also save a lot on future repairs.
To stop and fix a heat pump’s vibrations, add sound-dampening mounts, tighten the fan blades and retaining bolts, then replace the motor if the bearings grind. You can also use a compressor blanket to reduce the noise output, repair the bent areas of the heat pump cage, and insulate your air ducts.
In this article, we’ll show you how to repair your heat pump to stop its vibrations. We’ll also provide you with a handful of preventative maintenance tips and tricks.
1. Connect Vibration Reduction Pads
Sound-reducing pads will drastically lower the noise output coming from your heat pump. The Heat Pump Store explains vibration pads are some of the best tools to handle vibrations anywhere in your HVAC system. You can place the pads behind wall-mounted systems and under floor-mounted systems.
The LGB Products Sound Isolation Pads (available on Amazon.com) are 4” x 4” x ⅞” (10.16 x 10.16 x 2.22 cm) pads that sit under each of your heat pump’s legs. They’re available in four sizes to fit your HVAC unit. Each pad can handle up to 960 pounds (435 kg), making them more than suitable for heat pump vibration issues. They’re made of rubber foam with tapered edges (similar to sound dampers in recording studios).
Consider these suggestions when using sound isolation pads:
- Make sure the pads are centered under each leg for optimal balance.
- Never use sound isolation pads less than ¼” (0.64 cm) thick (they don’t dampen the soundwaves enough).
- Use a leveler tool to ensure the heat pump is level after adding the pads.
2. Secure the Fan Blades
Heat pump fan blades are durable and reliable, but they can wear down and start to wobble. When the blades are misaligned, they make vibrating and rattling noises. The good news is that all you have to do is tighten the retaining bolt and check if any of the fan blades need to be replaced.
Follow these steps:
- Turn off the power going to the heat pump.
- Remove the four to six retaining bolts to lift the top cage off of the heat pump.
- Inspect each of the blades, then replace them if they’re rusted with holes or if they’re bent.
- Use a rust inhibitor to remove and prevent rust from loosening and damaging the fan blades.
- Tighten the fan blades with their respective bolts, then secure the top cage with the aforementioned retaining bolts.
It’s also a good idea to use the same rust inhibitor on any rusted parts in the HVAC unit. Rust can quickly spread and shred a heat pump, especially if it’s outside.
3. Tighten All of the Screws
According to Doc Savage Air, tightening all of the screws throughout the heat pump might be the only thing you need to do. Loose, stripped, and rattling nuts and bolts can cause vibrations that get louder with time. Fortunately, you rarely need to replace the screws. That being said, stripped screws should be replaced as soon as you can.
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Consider using screw glue if you want to prevent your HVAC bolts from loosening down the road. It solidifies the bond between the threads, making the screws much more reliable. Never use screw glue on stripped bolts; you’ll worsen the problem and make it very difficult to change the screws with new, threaded ones.
Loctite Threadlocker is an excellent option because it goes on blue to let you know where you’re applying the glue. It tightens the screws after you thread them into the heat pump. This impressive screw glue dries in 10 minutes and completely cures in 24 hours.
4. Replace the Damaged Motor
Damaged heat pump motors vibrate because the bearings grind. Once moisture gets into the motor bearings, the bearings rust. This rust leads to loud noises and overheating. It can eventually cause permanent damage to the motor. This damage spreads to other parts of the HVAC system, too.
Try this method to replace a damaged heat pump motor:
- Turn off the power going to the heat pump.
- Remove the top cage and disconnect the wires going to the compressor (you might have to do the same to the capacitor, depending on the make and model).
- Disconnect the top cover over the compressor to expose the compressor motor, then remove the connected wires and label them.
- Place a like-for-like motor in the compressor, then attach the labeled wires to their corresponding terminals.
- Reverse steps 1 through 3 to tighten and secure the heat pump.
5. Add a Compressor Blanket for Sound Suppression
Compressor blankets can work wonders when it comes to making your HVAC systems much quieter. HVAC How To suggests wrapping your compressor with a compressor blanket if it’s too noisy. Always make sure the noise isn’t coming from the compressor motor bearings, though. This grinding noise will worsen.
Furthermore, you should only choose a compressor blanket recommended by the heat pump manufacturer. Using an oversized blanket (or one that’s too thick) can overheat the compressor and cause permanent damage to the heat pump. It can also increase unwanted noises by overcrowding the heat pump.
6. Repair or Replace Bent Cages
Many heat pumps have security cases. While these cages prevent overheating, scuff marks, and many other issues, they can also have adverse effects. For example, a bent security cage can rattle against the screws and other components.
Consider these five factors if your heat pump’s cage is bent and vibrating:
- Always replace any bent cage portion that’s touching an internal component.
- Bending the cage in the opposite direction to correct the issue can weaken the metal and expose it to rust and corrosion.
- If you replace the bent cage, always use one provided by the company to ensure it’s the correct dimensions.
- Never work on your heat pump without turning off the circuit breaker, even if you don’t intend to touch anything electrical near the cage.
- Inspect anything the cage vibrates against since there’s a high chance of scuff marks, corrosion, and other damage from metal-on-metal friction.
7. Prevent Temperature Fluctuations
Rapid temperature changes can quickly alter the way your heat pump operates. For example, your heat pump will be noisy if the pipes expand and contract from sudden freezing temperatures. The same can happen if the pipes or heat pump gets extremely hot out of nowhere.
All you have to do is insulate the pipes and the heat pump. Insulation can prevent freezing and overheating. You can choose between insulation tape (which is best for areas with mild to moderate temperature changes) or insulation foam (which is ideal for places that experience extreme weather patterns and shifts).
Note: Air leaks can cause rapid temperature changes, knocks, and vibrations. Always check and repair leaks throughout your HVAC system (including your heat pump) during your recommended annual HVAC checkup.
Vibrating heat pumps can be annoying, but there are more than enough ways to stop the sounds and get back to normal operation. If your heat pump doesn’t stop vibrating after making all of the aforementioned changes, it’s time to contact an HVAC technician to inspect and repair the heat pump.