As you use your mini split system to cool your home, the cooling process causes condensation.
While you may see condensation as a problem, it's proof that humidity is being removed from the indoor air.
However, you still must remove the condensate. If you don't, the water can overflow and damage your walls, ceilings, floors, and possessions.
You can remove condensate in various ways. Some units require pumps, and others simply use a piece of tubing to gravity-drain the condensate outside.
Drain Tubes & Pipe Runs
The most common way to remove condensate is using a 5/8" inner diameter vinyl drain tube. This method is standard for nearly all wall mounted and floor mounted indoor units.
When using flexible vinyl tubing to expel condensate, be careful that the tubing does not become kinked, as this will prevent the water from escaping and could cause water to overflow out of the indoor unit. Using braided tubing as opposed to standard clear tubing greatly reduces the chance that the tubing will kink.
Wall and floor mounted units rarely include condensate pumps for helping remove the water, so they rely on gravity to remove the accumulated moisture. This means that the drain line must be sloped downward all the way to prevent backups. For this reason, it's important that the hole through which your drain line runs be 1/4" to 1/2" lower outside than it is inside. This will help keep the drain line angled down for proper drainage.
In some cases, relying on gravity to drain moisture from an indoor unit is not possible. If this is the case, a condensate pump may be required.
Units with built-in lift pumps, like ceiling cassettes and concealed ducted units, typically use 1" or 1-1/4" rigid PVC rather than flexible tubing. This makes it easier to maintain an appropriate slope over a longer horizontal run.
In other cases, it may be possible to drain several units using a single line. In such applications, you should refer to the manufacturer's guidelines and your installer's recommendations to ensure your piping can handle the volume of water the connected units will produce.
What's Used to Pump Condensate Outside?
Units that typically need a condensate or lift pump usually come with one included. These include ceiling cassette units, concealed ducted units, and some ceiling suspended models. Wall mounted and floor mounted units are generally intended to be mounted on an exterior wall where they can gravity-drain through the wall without the assistance of a condensate pump.
However, if you use one of these units on an interior wall or below ground level, you'll need something more than drain tubing to lift and move that condensate to a drainage point; in which case, an optional condensate pump can be used to move the condensate to a suitable drain location.
Types of Condensate Pumps
While all condensate pumps essentially do the same thing (remove condensate), there are several styles to choose from. Regardless of form, condensate pumps all consist of the same basic components. A reservoir connected to the drain pan of the indoor unit collects the water produced during cooling or drying operation. Once the water reaches a certain level, a built-in float switch turns on the connected condensate pump. On many models, the float switch can also act as an alarm that can turn off the indoor unit to prevent an overflow in the event of a pump failure.
Standard Condensate Pumps
A standard condensate pump is concealed out of sight in a ceiling or wall. The reservoir is installed inside the indoor unit, and connects to the unit's drain pan so it can collect the condensate. These types of pumps serve most applications very well as they're out of sight and generally quiet.
High Suction Condensate Pumps
Similar to the standard condensate pump, you can get high suction condensate pumps with extra suction power, or high head as it's called. These install the same as a standard condensate pump, but are more capable of lifting condensate higher and further.
These are ideal if you're installing a unit below ground level and need to pump condensate up to a higher elevation before draining it outside. Because the pump can be located further from the space being conditioned, these high suction pumps are excellent in applications where noise needs to be minimized.
Low Profile Condensate Pumps
If you're not interested in installing the condensate pump in your ceiling or wall, there are some less intrusive options as well. You can opt for a low profile condensate pump that fits inside the indoor unit itself, so it's completely out of sight.
Surface Mounted Condensate Pumps
And for ease of maintenance, there's a surface mounted condensate pump that is installed directly to the bottom of the mini split unit itself. The pump and reservoir are located on the outside of the unit in a small, easily-accessible box. While this may not be the quietest option, it's much easier to access should you need to clean or repair any part of it.
So now you know your options, and you know what benefits each option serves. Considering what preferences you have for your home can help you to decide which style(s) of condensate removal will best serve your needs.
If you still aren't sure what the best method of condensate removal is for you, or if you have any concerns about compatibility, you can always feel free to call our experts for advice at (886) 554-4328.