Frequently Asked Questions (FAQ)

If you have a question about any aspect of heating, cooling, ventilation and air quality, this page contains a collection of frequently asked questions with concise answers.

For more in-depth information, there are fully detailed articles associated with the question subheadings on this page, that are linked to for your convenience.

Let's get started:

Which Portable Air Conditioner Works Best?

Generally speaking, the best working and most efficient portable air conditioner is one that has dual exhaust hoses and has a self-evaporating technology that re-uses the condensate that builds up inside the unit to assist in the cooling process.

This type of portable AC produces a better cooling output to energy usage ratio than standard models with a single hose and no condensate management system.

Read more about what is the most effective portable air conditioner here.

Which is Better: Window or Portable Air Conditioner?

In general, window air conditioners are more efficient, affordable and effective than portable ACs, making them a better choice of cooling solution.

A common reason people avoid window units is either they don't have the right kind of windows or there are restrictions on installing them in their building.

While portable units are more flexible in their placement, window units produce much more cooling per BTU rating and represent a more economical form of cooling.

Read more about which is best: window or portable air conditioner.

Which is Quieter: Portable or Window Air Conditioner?

Noise matters to a lot of people. Different air conditioning units produce different levels of noise that can range from merely a background hum to a relatively loud and irritating sound.

Sound level is measured in decibels (dB). The higher the number, the louder the sound.

In general, most portable air conditioners produce a louder noise than window AC units of similar cooling capacity.

Many portable AC units produce around 60-70 dB, while the majority of window AC units tend to produce around 50 dB, which is measurably quieter. If AC noise bothers you, choose an air conditioning unit with the lowest dB rating.

Read more about portable or window air conditioner: which is quieter.

Must Portable Air Conditioners be Vented Out a Window?

By their very nature, all air conditioners produce hot air as well as cold air. The hot air must be vented to the outside to prevent the room actually heating up instead of being cooled!

Fixed air conditioning units (mini-split, PTAC and central air) are always installed with fixed ducting that carries the hot air out of the building. Window units are already installed in a window and are naturally vented to the outside.

However, portable air conditioners require venting via a suitable outlet such as a window or an external wall.

Once the portable air conditioner is in position, the exhaust hose must be attached to an opening to the outside. This is so that the hot air can be exhausted out of the room.

Read more about whether portable air conditioners must be vented out a window or not.

What Happens if You Don't Vent a Portable AC?

Venting a portable air conditioner is important because it removes the hot, moist air that the unit produces from the room being cooled.

If you don't vent this hot air, it will just build up in the room, cancel out the cool air produced and create a net heating effect. The moisture in the air will also continue to build up, increasing humidity and making the room feel even more uncomfortably hot.

All air conditioners remove moisture as well as heat from the indoor air.

The lower the humidity in a room, the cooler it will feel. So by venting the hot, moist air out of the room, the more comfortable it will feel.

Can Portable Air Conditioners Give Off Carbon Monoxide?

No they can't. This is because AC runs on electricity and operates with a closed mechanical refrigeration process inside the unit.

So you do not have to worry about carbon monoxide emissions from a portable AC into your home.

Does a Portable AC Need a Drain Hose?

For a portable air conditioner to run continuously, a drain hose is necessary.

This is because condensation builds up inside the AC unit as it runs. The condensate forms droplets of water that drip down into a catchment tank that gradually fills up.

So what happens if you don't drain a portable AC, or you don't empty the water tank?

When the tank is full, the AC unit will emit an alarm and automatically shut off until the tank is emptied.

The drain hose empties the water from a condensate tank near the base of the unit. The drain hose can empty into a bucket or down a drain if there is one nearby.

Where Does the Moisture Go in a Portable AC?

As all portable air conditioners by their very nature remove moisture from the air as they cool, that moisture condenses and must go somewhere.

The water drips down into an internal water reservoir, usually a tank located near the base of the unit. This tank is then either manually emptied or drained through a hose into a convenient outlet.

What is Self-Evaporating Portable Air Conditioner?

A self-evaporating air conditioner is one that reuses the moisture that is collected from the air to assist in the cooling process, making the unit more efficient and economical.

This type of free standing AC eliminates the need for emptying the collected water from a tank, reducing the need for manually draining periodically.

Note: These units do retain a water collection tank that is used when the appliance is set to its dehumidifying mode. In this operational mode, a great deal of moisture is removed from the air and collected in the tank which muct be drained or emptied manually when full.

Read more about what self evaporation in air conditioners means.

What Portable Air Conditioner Does Not Need to be Drained?

See above: A fully self evaporating air conditioner does not need to be drained frequently under normal operating conditions, unlike normal portable units.

However, in areas with high humidity, there may be more moisture removal than normal, which can exceed the amount of moisture that can be re-evaporated and expelled through the vent hose. In this case, some moisture can still condense into the tank, which will need to be emptied when full.

Read more about what portable air conditioner does not need to be drained.

What is No Drip Technology?

Some portable AC units are advertised as having "no drip technology" which basically means the unit will not drip condensed water into a catchment tank that requires constant emptying.

This type of self-evaporating air conditioning model uses an integrated condensation exhaust system designed to automatically expel condensed moisture that is created during the cooling process.

This is provided as a convenience for the user as it eliminates the need for regular manual emptying of the bucket/tank.

Note: However, when the unit is operated in "dehumidify" mode, where it acts as a room dehumidifier, a great deal of moisture can be removed from the air, too much for the condensate exhaust process to cope with. In this case, the tank will fill with water and must be manually emptied or drained with a drain hose (generally provided by the manufacturer).

What are the Advantages of a Window Air Conditioner?

A window AC unit provides many benefits over portable units when it comes to cooling a room.

These include not taking up any floor space, no need for an exhaust hose, lower energy costs, higher output and faster cooling capability, lower noise levels.

What are the Disadvantages of a Window Air Conditioner?

There are some disadvantages to installing a window AC unit in a room, but these are few when compared to portable units.

They include taking up window space and thereby reducing the amount of natural daylight that can enter the room, more difficult installation, can prove to be unsightly when viewed from outside and they are fixed and cannot be moved from room to room.

Can One Window AC Cool Multiple Rooms?

Unfortunately, a single window air conditioning unit is not designed for and not suitable for cooling more than a single room.

This is generally due to it being fixed in position and cold air does not travel well over distance, as the flow of cool air tends to simply halt at the doorway.

To cool multiple rooms, it may be worth considering installing central air for better economy on a room by room basis.

Summing Up

This page will continue to grow as more questions come up about heating, cooling and HVAC in general.

If you don't see an answer to a question you have, either call back at a later date as I am adding to this page. Or you could shoot me a message via my contact page and I'll research your question and find a suitable answer for you.

top of page icon