November 5, 2019
A heat pump can often be a noisy system. But when is your unit just being loud, and when does the noise indicate a bigger problem?
First of all, it helps to know how a heat pump works. As you may know, a heat pump has both an outside and inside unit, with the outside being almost exactly like an AC.
In fact, the only difference between a heat pump and an AC unit is that the heat pump contains a valve that changes the flow of your refrigerant, and makes it condense inside your home instead of outside. Now, heat is released inside your home.
What happens when the heat pump valve switches and changes the flow of the refrigerant? A whole bunch of noise happens, that’s what!
Normally, your heat pump outdoor unit will be blowing cold air out of the fan on the top. However, you may want to put your heat pump in defrost mode so that you can clear up any frost that’s collected on the coil.
When the heat pump goes into defrost mode, you’ll hear aloud, low hum, like the low note of a trumpet! You’ll feel heat instead of cold coming out of the top, and the fan will no longer be running. You may even see steam! All of this is normal because the system is defrosting the ice off the coils.
Then, when your system exits the defrost cycle, you’ll hear a loud noise of air pressure being released, and you’ll hear the fan coming back on again.
Another common heat pump noise in the winter is from the unit turning on or off.
The compressor will usually be quite noisy because its whole job is to compress air and refrigerant. The most common type of compressor, a scroll compressor, is quieter than the other type of compressor, a reciprocating compressor (because that type uses loud pistons).
The scroll compressor type of heat pump is more efficient and reliable, and we recommend you install that type, because repairs are cheaper, too! But this type of compressor still makes noise when pumping refrigerant, and when it turns off, the air pressure taking a moment to equalize can cause loud “blowing” noises!
Similarly, if the heat pump’s outdoor unit is turned off, but you still hear a low buzzing noise, that’s because of the solenoid coil on the valve. The buzzing comes from the low voltage electricity of the coil and is constant.
If you hear a loud squealing noise, that’s hot gas going through the valve, and it means that your system needs a discharge valve!
Or, if it’s not a buzzing or droning you hear…but more of a clanking…then it’s likely your fan blades are hitting another internal component.
In winter, it’s possible that ice is stuck in your blades, too. You’ll want to turn the unit off right away. The fan blades hitting something could unfortunately do a lot of damage, and cause a hole in the tubing, making refrigerant leak everywhere!
Overall, a somewhat noisy heat pump is just the reality of the system. However, it should really only be loud during defrost mode, or if you have a reciprocating compressor instead of a scroll compressor.
But there are other culprits that could cause a noisy heat pump too: a malfunctioning reversing valve, not enough refrigerant, or a bad motor.
These aren’t issues you can fix on your own, so if you can’t easily diagnose and fix the problem just by looking at it, then it’s time to call a professional. At Parker & Sons, we provide expert air conditioning repair in Tucson and Phoenix, 24 hours a day.
We’ll shush that noisy heat pump! Schedule an appointment today!