A Complete Guide to Residential VRF AC System
Updated: Feb 16
While looking for your new air conditioning system for your home, residence, hotel, restaurant, and small office space, the basic problems that we face are:
· Placement space for outdoor
· Excessive number of outdoor units
· Looking for an Indoor Unit other than a Split type unit
· Piping distance exceeding the permissible limit for ac to function properly
· Hot air from the outdoor exhaust does not allow you to use your balcony
· Different temperature requirement for different rooms is house or office
· Regular AC draws too much power and you are looking for a more efficient version for Inverter AC
· Reliability of the VRF System, the frequent problems on peak load temperature
· Maintenance of VRF AC System, is AMC also required?
· Can the System be controlled through a mobile or Central Controller?
· Can we buy the indoor and outdoor separately?
· Will the VRF system work at the ambient temperature of 52-55 degrees centigrade
· How much does the AIR quality affect the performance?
· Does the VRF System also has a built-in air purifier?
· Which brand should I prefer and what suits my budget?
There are answers to all these problems and we are going to address them one by one.
What is a VRF AC System
In the VRF System, we regulate the flow of Refrigerant in the System, refrigerant is the coolant that is being used to transfer the heat from indoor to outdoor while the system is working on Cooling Mode and also transfers heat from outdoor to indoor while the system is working on Heat Pump Mode, another benefit of the VRF system is the Inverter Compressor that allows the unit to perform on Partial Load and full load as per the requirement demanded by the operating indoor units in the VRF AC System. We also have the options of designing the interior design of the room or space in a much better way by the application of various indoor units such as one-way cassette, traditional four-way cassette, ducted units, floor-mounted and ceiling suspended units. Another major benefit of the VRF System is the Flexibility of moderating the individual temperature of the different rooms or zones as per the requirements of the individuals. The control system can also be customized into different options such as Cordless, corded, and central controller options on panel and mobile.
Why Residential VRF System
All the major manufacturers are offering differentiated and specially designed VRF Systems for Residential Spaces which are compact, have a smaller footprint, lower profile, quieter operations, and higher efficiency. The Residential VRF Systems are being designed in such a way that a single outdoor unit is able to cater to 3-4 indoor units and this range can be expanded into single outdoor being able to cater to 15-20 units also but the size of outdoor increases considerably and is more often suited to larger mansions & Kothi type Houses and also medium to large office space.
These systems also have the edge on flexibility, compactness, and higher efficiency delivery. The system also has a greater life span as compared to the traditional system of the same capacity. The most distinguishing feature is the Branch Distribution box system in the residential VRF system this feature allows us to repair or treat the specific indoor unit in case of any problem arises, we do not need to put the entire system at a standstill. The bigger version of VRF that is suited for larger space usually has the Y joint system for the distribution of refrigerant.
The outdoor units for these systems are generally looking similar to the traditional split-type outdoor unit but slightly higher in length, and are front discharge and some of the higher capacity version are top discharge models and are supposed to be placed on the roof or a location with a headspace of 6-7 ft and clear sky. The front discharge models can be placed on the balcony or roof as per design approval.
The traditional system has a big drawback that the outdoor and indoor have an effective piping length of 10-15 ft on a vertical and horizontal scale, the Residential VRF System hugely cover this drawback by offering the effective piping distance up to 100-130 ft. The size of the outdoor is so compact that it can be hung from the ceiling also and does not need to be placed on the floor only, this we are able to reduce the footprint of the system.
The heart of the AC unit is considered as the Compressor unit which in the traditional system are Rotary type models. In the Residential VRF system, we will find the Twin Rotary designs, Swing Compressor, Digital Inverter Scroll type and Modulating Scroll all of these have advantages and disadvantages when compared to each other, but in a nutshell, are way more efficient than the traditional system. But technically for most of the VRF Systems that are having higher operational hours we have seen that digital scroll compressors are very efficient and on the other hand Modulating scroll compressors are reliable.
Options available in the market today
There are many brands of VRF System currently available in the market today, in the context Indian Market there are quite a few brands available in this segment, and once a customer tries to identify the perfect fit suitable to their requirement, they are left with more confusions rather than a resolve on this question. First of all, I would suggest that we must analyze that if we even require the VRF System in the first place or not, because more often than not the traditional system suffices all the requirements, we have with the Comfort Air conditioning. Also, if we consider the VRF system with the traditional system we see an exponential rise in our budget, which is basically because the equipment cost for the VRF System is almost double if compared to the traditional system with base features, so if we are looking towards a bit luxurious end of the Air conditioning system which has premium features, we should definitely opt for the VRF system.
Now that we have considered that we really want the VRF System, still, the basic question remains that which Technology of the VRF AC we should opt for and the Brand that fits our Budget, as mentioned in the company brochure we can see that only Fujitsu General, Mitsubishi Heavy and Trane have mentioned that their mini VRF system that is suitable to Residential Application has a working temperature in between 50-55 degree centigrade and the rest of the brands have mentioned working temperature below 45-49 degree centigrade (these include major brands such as Mitsubishi Electric, Daikin, Hitachi, LG, Bluestar, Toshiba, and Samsung) Now if we consider the Price point of view we can see that the Equipment cost can be divided into 3 basic categories Basic, Medium and Premium Models and these are bifurcated as below.
1. Basic- Bluestar, Voltas, LG, Dunham Bush, Carrier
2. Medium – Daikin, Toshiba, Trane, Samsung, Hitachi
3. Premium – Mitsubishi Heavy, Mitsubishi Electric, Fujitsu General
The Basic Category can be negotiated around 35-40k per HP, the Medium is negotiated for around 40-50k per HP, and Premium Models are negotiated around 50-60k per HP, but there is a significant difference in the pricing of the equipment when the Indoor is upgraded to other than Hi- wall split units because there is factor gain of around 50% if we use Cassette or Ducted Indoor units instead of Hi wall Split Units and there is a factor gain of 70-80% if we account One-way cassette units.
The Installation or low side calculation is negotiated in between 12-15k per HP if we take Hi wall Splits and other ductless systems and 15-20K per HP if we consider Ducted Units.
For a much better design of the VRF HVAC system please refer an HVAC Consultant and discuss your requirements in detail to design your VRF System in the most tailor-made specification, because this is the most advantageous feature of the VRF AC System that they can be customized as per your requirement.
Maintenance and Repairs
The VRF AC System is a complex electro-mechanical unit and requires periodic maintenance and if we see the Major Brands, they all offer Annual Maintenance contracts which are generally around 3-5k per HP per annum. But since these are very heavy-duty units and their maintenance depends a great deal on the Installation, we can say that in the first few years the AMC is not very highly recommended unless you require an Accident or breakdown to be resolved in 24-72 hrs, otherwise, the Brands themselves support with providing 24 hrs kind of assistance and we can pay on Ad-hoc basic and clean the filters on a bi-annual basis.
We also do not recommend that the Copper Pipe which is used to carry the refrigerant do not be chiselled in the wall and be carried on cable tray that can be concealed in the False Ceiling or camouflaged in the ceiling itself, because all the VRF units have an onboard computer that in an event of breakdown indicate an error code that helps the mechanic to identify the problem and in case of gas leakage in the piping system, it becomes very difficult to identify and do the repairs if the piping has been chiselled.
Another major event of breakdown can be avoided if we get the condenser fins and tube coated with the anti-rust coat, this can also be an Epoxy-hardener coating that improves the life of the VRF unit by preventing rusting of the condenser coil system.
For the protection against Electrical Surge in the power supply, we highly recommend the installation of Servo, which is basically a Voltage Fluctuation stabilizer.
These features are not part of the package that Manufacturers or Brands of VRF AC System offer in general but can be added after the basic functions are operational. The 2 important add-ons that we would like to mention are
2. Air Filtration System
Automation in VRF is divided into 5 basic categories
1. The AC Units or Compressor Computer
2. The Temperature regulator or control system
3. PLC devices (Programmable Logic Controller)
4. Web interface and Gateway modem
5. Control Interface on Web or Android
These parts are then put together on a platform that is integrated to act on a specific program or offer controls to the user, the most popular interface for the integration of these modules are LonWorks, BACnet, Modbus, and oBIX which are the standard open protocols for the communication between the machine units, controllers and programming devices. Automation is a very cost-sensitive addon for an HVAC System as it can increase the budget spending drastically, so we refer these products to clients who want an advanced level of controls for their VRF AC System. Many brands such as Daikin and Mitsubishi Electric have advanced control systems onboard the VRF/VRV System that is integrated with the BMS architecture and provides personalized temperature controls for specific zones.
Air filtration is a necessity looking at the air quality index, the AQI in Delhi NCR is in between 300-500 levels which is not considered a very safe level of air quality, but getting an air purifier changes the air quality inside your home and provides you AQI level of 50-100 which is way better than outside air, so what if we can integrate the Air purifier with the HVAC Units. The air quality has few different parameters
1. PM 2.5 (µg/m3)
2. PM 10 (µg/m3)
The technologies that are available to regulate these are Ultraviolet Germicidal Irradiation (UVGI), Photo hydro ionized oxidation plus (PHIO+), Cold Plasma Technology (CPT), Photocatalytic oxidation (PCO)
This kind of filtration is available in many brands like Bluestar that are offering UV light in build lamps in the Ducted system and TFA (treated fresh air) System that regulate the level of CO2 in the inside air, we have the option of providing a separate AHU coupled with an outdoor unit which has the provision of modulating the flow of air from outside with different stages of the filtration process and also conditioning it to a temperature range 10-15 degrees lower than the outside air. There is also the option of HRV (heat recovery ventilator) units that conserve the enthalpy of the air while it is exchanged from the outside air.
There are a few solutions available for Ducted and Cassette type indoor units which are from Magneto cleantech that are magnetic filtration system.
For More Details Please contact us on +91-9599924960, we offer Designing, Supply, Installation, and Maintenance services for VRF AC System. Clouds Inc is a Reliable and Trusted VRF HVAC Contractor. We can offer the most competitive rates for VRF AC System for Mitsubishi, Toshiba, LG, and Hitachi and also Home VRV system from Daikin.