Ductless Mini Split Air-Conditioners

Ductless HVAC systems or often known as mini-split systems are beautifully efficient and provide consistent room comfort. A ductless heat pump or air conditioner typically consists of a wall-mounted indoor unit combined with an outside compressor. It can be used in a situation where a window AC unit or baseboard heating would be considered, such as a new addition or sun-room to a house. But unlike window units, ductless units require only a very small hole to be drilled into the wall, making them less vulnerable to air leakage and security problems. Plus, they're less visible and much quieter.

Depending on your home’s construction, ductless systems can make sense in a variety of applications, including whole-house heating and cooling. But there are certain situations where ductless has a clear advantage:

  • Flexible solution. Ductless cooling and heating are a cost-effective way to replace inefficient window units, space heaters and electric baseboard heaters or simply a cost-effective way to cool an otherwise warm space in your home or office. These have an advantage to improve the temperature in a specific room.
  • New additions: garage apartments, bonus rooms, sun-rooms. The main benefit of ductless here is that it will be properly sized for the new space and won’t steal air from other rooms or overload your old HVAC system.
  • Saving money and cost-effective. Ductless A/C systems are much more efficient than conventional duct systems. Ductless systems operate on less power, they are smaller than traditional air conditioning systems, and because the air is delivered directly to a room, there is no loss in efficiency that occurs within the duct of
    conventional systems. With ductless systems, you can set the temperature in your bedroom cooler than the rest of the house saving you money on your electric bill and still ensuring you don't develop a mold problem.
  • Serving multiple needs under one roof. Does your family constantly fight over the thermostat? Ductless is ideal for creating independent temperature zones in different rooms, and although you can install zoning in a traditional ducted system, it won’t be as efficient.
  • Lower Carbon Footprint. Ductless air conditioners operate on the same principle as your refrigerator and use just about the same amount of electricity. The small size of a ductless cooling system and the zone capabilities that they provide allow for greater energy efficiency. Ductless cooling and heating systems follow ENERGY STAR guidelines. This makes them far more energy efficient than conventional HVAC systems. Better energy efficiency saves money and also reduces your total carbon output.
  • Quick and easy to install on a wall. Ductless systems are far less complicated and invasive to install than a conventional unit. A two-man crew can easily install a ductless unit in half a day.
  • Adding AC to a house with no existing duct work. Ductless isn’t cheap, but it’s less expensive than adding duct work to an existing house.

Proper system sizing and installation is absolutely critical to getting the touted benefits from a ductless system. Although a DIY approach is possible, it is advisable against it as you’ll likely void the warranty. It is better to hand over the work to reliable ductless air-conditioning contractor that has experience dealing with these projects. Ductless will never work properly if the system is the wrong size, the wall penetration isn’t sealed correctly, or the sensitive electronics are mishandled. And you have to be able to handle refrigerant according to EPA guidelines. The extra money you spend to have a pro do the job is worth it. Preventive Maintenance Support Services has installed mini splits AC in many different projects, in smaller scale such as individual rooms to home additions, new construction, apartments and condominiums.

To install a single unit in a single room (assuming there are no complicated construction issues with your house), expect the job to take around three-to- seven hours. Multiple rooms and tricky construction may push installation time up to a week. Even so, you can ensure that mini split ac installers should be working within these amounts of duration to finish the project. Our conditioning team in Preventive Maintenance Support Services has known as reliable Ductless ac installers for our valued customers.

Ductless Air-Conditioning Efficiency

Ductless air-conditioners are much less expensive than traditional "split systems". Convention air-conditioners have large compressors to push liquid refrigeration through an "expansion valve". The liquid rapidly expands cause a cooling effect know as the "latent heat of vaporization". This process sucks the heat out of the air flowing through the unit.

Conversely, a mini-split system uses a "metering valve" not an expansion valve. A metering valve has no restrictive orifice and therefor, the compressor is much smaller. The liquid refrigeration then slowly boils off, thereby sucking the heat out of the air flowing through the unit. This is the same technology your refrigerator works on and as you know, a refrigerator uses much less power than a convention air-conditioner.

How Many Square Feet Can a Ductless Air-Conditioner Cool?

12000 BTU's of air-conditioning (one ton) can cool 600 square feet of room space on average. But, this depends on how many windows you have, how well insulated to roof is, how tall are the ceilings, the rooms exposure to the sun and how well the room is sealed. So, sometimes more tons are needed. As an example, we recently installed a 1.4 ton mini-split in a 300 square foot sun-room because the number of windows and ceiling height.

Mini Split A/C Energy Efficiency

A Case Study

Recently a client installed a ductless a/c unit in each room of the house. The house is approximately 3500 square feet and has a conventional split system. It’s and older system with a 13 SEER efficiency. The entire house is kept at 79 degrees using the conventional a/c system. This keeps the humidity down and eliminates mold. When a family member enters a room, they simply set that rooms temperature as they please. Everyone can keep their room at whatever desired temperature at nigh as they sleep. They can turn the unit on in the living room and off when they leave. The cost saving on their electric bill has been dramatic. It has almost cut the electric bill in half. It went from $450.00 per month to $250.00

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So what happening here is the smaller units keep the house at 79 and the large convention unit rarely runs. The smaller units have smaller compressors and lower the over all energy consumption.

Installing a Ductless A/C system

A small 90 BTU unit can run on 120 volts and can even be plugged in to a wall outlet. Larger units run 240 volts. That's the same power you hot water heater and drier use. So the first consideration is supplying electrical poser. You can run new wire through the attic, but the outside unit needs the power so conduit is normal run from the main service panel around the outside of the house. An electrical permit is  needed and the circuit needs a GFI.

We normally mount the condenser on a wall bracket on the wall opposite of where we want the evaporator head installed. It is then a simple thing to cut a hole in the wall for the Freon line set and control wires needed for the inside until. The condenser can be mounted on a flat roof if aesthetics are a concern.

The indoor unit generated a water flow. The piping can simply be piped outside or a pump can be installed to rout it else where.

Permitting a mini split air-conditioner

As mention above an electrical permit is required. That's generally not a big deal and requires only one inspection from the building department. An air-conditioning permit is also need. If your simply adding the unit to a bedroom there will also be no problem. You wont need any calculations for the sizing of the unit because your main house a/c system covers that. In that scenario only one inspection will be required.

So if these permits are innocuous why get them? Because they are cheap and its always better to get a permit than avoid it. Some people tell me they don't want a permit because they afraid the inspector will find something wrong and cause problems. That has never happened in my over 30 years experience in the trades. Building is just looking at the plans for the permit and doesn't care about anything else. Code enforcement is the branch that looks for problems not the building department. Never be afraid to get a permit and beware of those that tell you otherwise.

If your looking to air-condition an outdoor enclosed space permitting will be a problem. You cant air-condition a patio space without upgrading it. Read more on sun-rooms here


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