The temperatures are supposed to drop below freezing this weekend. We’re expecting lows in the 20s in Central Florida, and here is what you need to know about your home’s HVAC and plumbing—and whether you need to call a professional.
This PSA will cover some of the most common calls we get during cold weather (that often don’t actually require a technician to come out):
- Frozen or steaming outdoor air conditioning unit
- Strange noises from the outdoor air conditioning unit
- Heat pump can’t reach the set point indoors
- Air coming out of the vents isn’t warm
And a few HVAC & plumbing best practices:
- DON’T use emergency heat
- Don’t run your pool heater
- Insulate and trickle small outdoor pipes
The Heat Pump Outdoor Unit is Frozen, Steaming, and Making Weird Noises
During the upcoming cold snap, you may notice three concerning things with your outdoor unit:
- Frozen unit
- Smoke or steam
- Loud, strange noises
In most cases, these are normal. You should let the heat pump continue to run, as it is trying to defrost its outdoor coil. Turning the unit off will only delay the defrost process and will make the frost buildup worse.
Since the weather will drop below freezing, any water that gets on the unit will freeze. A thin layer of frost will form. The picture below shows a normal amount of frost:
Heat pumps have a built-in defrost cycle to melt this frost off the unit. These cycles may happen on a timed basis or whenever a sensor drops below a certain temperature, and they may make the unit steam or make loud noises. During this defrost cycle, the sudden heat may also cause the ice to steam, which could look like smoke. There is also a shift in pressures inside the unit, which can cause some concerning noises for a few seconds, including whooshing, vibration, and even a little grinding. The steam and noises are normal.
If you come across those things, and they only last a short time, there is no need to call an HVAC contractor. Here is an article we wrote that goes into more detail about why these things happen during the defrost cycle.
The Air Coming Out of the Vents Is Also a Bit Cooler
The defrost cycle works by sending hot refrigerant (Freon) through the unit, just like in cooling mode. Defrost, in a nutshell, runs your unit in cooling mode for a few minutes to melt the frost. Your heat pump comes with electric backup heat to counteract the cooler air that results from the defrost cycle, but it may still not feel warm.
That’s normal and should only last for as long as the defrost cycle—around 10 minutes. The air coming out of the vents won’t be hot, but it shouldn’t be very cold, either.
You may also notice an odd burning-dust smell, especially if your heat pump has backup heat that hasn’t kicked on yet this year. This is also normal. This article explains what that is and why it happens.
When to Call for Help
You only need to call for help when the outdoor unit is completely covered in solid ice. Compare the photo above (normal) to the one below (abnormal—call an HVAC contractor):
Whooshing, vibration, and grinding that last around 15 seconds are all normal noises to hear during the defrost cycle. The following are not:
- Electrical buzzing
- Banging
- Chattering
- Squealing
During the defrost cycle, the air coming out of the vents won’t be hot, but it shouldn’t be a cold blast, either. If you get a cold blast coming out of the vents that lasts for a while, then you may need to call a professional.
A/C Unit or Heat Pump Can’t Keep Up
You may set the indoor temperature at 72°F but notice that your heat pump can’t keep up. Maybe it stays in the low 60s. As inconvenient as it is, that’s normal for older heat pumps in the low temperatures we’re expecting this weekend. Here is an article explaining why.
Heat pumps work by absorbing heat from the outdoors (yes, even in bitter cold) and bringing it inside. It’s harder to do that when the temperatures are below freezing, but your heat pump is still bringing in heat and working as designed. Newer heat pumps and furnaces will do better, but if you have an older heat pump, indoor temperatures in the low to mid-60s might be the best it can do.
Don’t Use Emergency Heat!
Even though it’s cold, don’t run the emergency heat if your heat pump is still running. Emergency heat turns the heat pump OFF and runs only electric heat, which is way more expensive. It’s only meant to be used when the heat pump has failed. If you can hear it running, it’s still working.
Instead, try to dress in warm clothes and have plenty of blankets on hand. Cooking warm food can also add a little bit of heat—every bit counts.
When to Call for Help
It’s time to call an HVAC contractor if the heat pump isn’t working at all, such as if:
- The thermostat is blank
- You don’t hear the heat pump running when the thermostat is below the set point
Now that the main HVAC concerns are out of the way, let’s look at some pool heating and plumbing tips for the cold snap.
Freezing Weather Tip: Don’t Run Your Pool Heater
Heat pump pool heaters aren’t designed to run and effectively heat the pool when outdoor temperatures dip below 50°F. We’re expecting temperatures WAY below that. During this cold snap, give your heat pump pool heater a break until it warms back up. (Most people probably wouldn’t want to swim in this weather anyway.)
While gas pool heaters typically do a better job in low temperatures, they’re expensive to run. If you’re not planning on swimming, it’s best to leave it off.
Here is an article with more information about why not to run your pool heater in cold weather.
Freezing Weather Tip: Trickle and/or Insulate Small, Exposed Outdoor Pipes
Those of you who used to live up north may remember dripping your faucets when the temperatures dropped very low. Luckily for us, the temperatures won’t drop THAT low, but you should still insulate and/or trickle small, exposed outdoor pipes and spigots.
Insulating the pipes slows down the effects of cold air on the piping. You can buy pipe insulation in standard sizes at most local hardware stores or use towels and trash bags. If using insulation, wrap the exposed portions of the piping from the bottom up. Then, seal over the insulation seams with duct tape. If you don’t have insulation, you can wrap a towel around the pipes and then wrap and tape trash bags over the towel. The towel keeps the pipe warm, and the trash bag prevents cold moisture from reaching the towel.
Even when you insulate those small, exposed pipes, water is still in there and can freeze when it stays still. To stop that, it’s a good idea to disconnect hoses and open the valves just enough to have a small trickle of water. It should be more than just a slow drip but not a forceful stream. This trickle keeps water moving, and the pipes are less likely to freeze.
When to Call an HVAC Contractor
Just a recap—you do NOT need to call an HVAC contractor if you experience the following:
- Relatively cool air coming out of the vents for 15 minutes or less
- Whooshing, vibration, or grinding noises lasting 15 seconds or less
- A small sheet of frost on the outdoor unit
- White steam coming out of the outdoor unit
- A short-lived burning-dust smell when the heat comes on
- Indoor temperature below the setpoint, into the low to mid-60s
Calling an HVAC contractor is recommended if you’re dealing with the following issues:
- Outdoor unit covered in thick sheets of ice
- Persistent banging, chattering, squealing, or electrical noises
- Cold blasts of air coming from the vents
- Blank or otherwise non-functional thermostat
If your HVAC system is having one of those problems, you can call Kalos Services or another HVAC contractor to take a closer look. You can reach us at 352-243-7099.
