A large HVAC system deals with high voltages and powerful fans. Installing or operating on one requires an exceptional amount of expertise. The high-velocity system forces air to move inside of a small duct to many rooms in the to. These are more difficult to work with and are chosen for confined spaces or because it moves a large volume of air quickly to out-of-the-way bedrooms.
Regular HVAC units use a powerful fan to move air through a duct that is 12 inches to 6 inches in diameter. With a high-velocity system, a more powerful fan effectively compresses air somewhat and forces it through a six-inch tube that might also be insulated to reduce the noise and vibration that would otherwise move through the building. This more powerful air conditioning system requires more regular maintenance.
There are many steps in figuring out how best to install the system. The first is just figuring out the precise size of the AC system needed. This is referred to as “calculating the load,” and it just means that the high-velocity device installed should be a perfect match for the size and needs of the building. Cubic space is one way to figure it out while using a gauge like SpacePak is another.
The next step is to find the right place to install the fan coil unit. This device differs from conventional units in that it is preferably sheltered from the outside. This specialized HVAC unit is typically installed in the attic or crawlspace. The unit itself can be very long as opposed to a large box that sits on bricks outdoors. The chosen space might even be a closet, but there must be space for the condenser and its drainage.
The next step is to cut a return air socket in the wall or floor where the unit is installed. The hole, as well as the return air ducting, must be an exact match with the position of the mounted air conditioner. There should be enough clearance for all the duct parts. If installing the HVAC unit in the attic, then a secondary drain pan might become necessary. It is best to install the air conditioner first and then determine where the ducting holes should go.
It is important to construct a platform appropriate for the high-velocity system and its adjoining parts. Indoor areas might have fragile surfaces such as drywall that need to be reinforced. The platform is often a 2-by-8 inch wooden board and joined to structure wood as opposed to the drywall. The unit usually comes with an insulating strip that reduces vibration and noise.
In the case that the unit has to be suspended from an above position, make sure to use the threaded rods that are meant for suspension. These rods should not be connected to the fan coil cabinet because other places are more stable and distribute the vibration better. If the unit is laid on top of the platform, then no bolting is needed because the weight of the unit will keep it stably in place.
Attaching the Supply Plenum Ring is a bit tricky because this intakes air and is designed to be a few inches lower than the bottom of the fan coil unit. These features might be because it was meant to be passed through a wall and beyond the support. In any case, any holes produce to facilitate this port should be made to match the height of the supply plenum ring.
The condensation drain is next attached to the fan coil unit and drains water that condenses from vapor. Since connection requires matching sockets, it is best to inspect the installation manual. Since the drain channels water by the force of gravity, it should slope downwards at a minimum of a quarter-inch per foot. It is better to have a separate drain system than to depend on a closed drain system.
The refrigerant lines are a bit different in this system than a box outdoor HVAC unit, but they are not difficult to install provided enough space. This job should be done by an air conditioner specialist because the coils have to installed airtight and then charged with refrigerant and then professionally inspected. It takes a license to do it.
The plenum duct is usually flexible and can be adjusted as needed to reach the supply tubing. However, all the parts should be located away from the fan coil unit as well as any other folds in the ductwork. This is just to prevent unwanted transfer of heat and vibrations. The plenum duct is made of 6-foot sections and can be cut by an air conditioning worker.
The next step is to install the terminator outlet as well as the sound attenuation tubing. These usually come packaged with the unit. It is best to first mark the location of the desired installation, making sure the ports are at least five inches away from any wall edge. The end result should be a four-inch hole using a 1/8 inch hole as a pilot for the saw. The free end of tubing has a device that snaps in place when installed in the hole.
The last step is to install the supply tubing. An important point is to avoid sharp bends in the tubes. Another is that the supply tubing usually comes in 100-foot lengths that often has to be cut and manually joined if branching. Refer to the manual on how precisely to join tubing sections, although a general rule is to cut two-inch holes for outlets and to use holes that orient at a 20-degree angle to avoid unneeded pressure on the tube.
Electrical connections are usually hard connections straight to power lines as opposed to using a conventional plugin jack. The thermostat might not require high voltage, but installing the power to run the unit itself generally requires a license. Every area will have its own laws regarding electrical connections and licensing, so check those rules and follow them as needed.