Any discussion on VRFs leads to a comparison with district cooling, as is most inevitable. What are your thoughts on the issue?

A VRF system is not an alternative to district cooling, which is a massive infrastructure project, whereas VRFs constitute standalone systems. So it is not appropriate to compare the two. However, VRFs could be compared to chillers, because both provide centralised cooling.

Is VRF the game-changer it is made out to be?

The market here is divided into DX and chilled water (CHW) systems. CHW is ideal for 22+ multi-storeyed structures. It makes sense, because the total capacity is high. DX is ideal for warehouses, G+3 and G+5 commercial buildings and villas. In the case of DX, we are witness to a change from ducted splits to VRFs, thanks to the initiatives of green building bodies. The change is happening also owing to the refrigerant, R-410A. Also, DEWA is trying to save power consumption per building to reduce per capita consumption, so as to reduce investment in infrastructure. Owing to these factors, VRFs are cannibalising what was a single-ducted-split market, and we are seeing chillers cannibalising district cooling.

In VRFs, you can get all the benefits of chillers, such as the COP of water-cooled chillers and, at the same time, do individual metering and skirt such issues as fouling of pumps and leakages. And further, if you analyst the lifecycle costs, VRFs will be cheaper.

At the same time, it is a horses-for-course scenario. Chillers are good for some type of applications, and district cooling is good for others.

There is no doubt that VRFs are better than chillers. In the case of chillers, the installation cost is higher. In VRFs, you have an outdoor unit and an indoor unit. In chillers, between the chiller and the FCU, you have other components, like pumps and a filtration system and also a complex mechanism to balance the water. The maintenance cost of chillers is higher, owing to water as a factor. Gas is 10 times more efficient than water, so there are huge cost savings to be had through VRFs.

You speak of the installation cost being cheaper, in the case of VRFs. Could you please substantiate?

The installation cost of VRFs will be cheaper by 40%, when compared to chillers. Plus, let’s not forget the time needed to set up a VRF system, which is less when compared to that of installing chillers.

VRFs involve one serial piping and one serial wiring, so it is a myth that installation is a tougher proposition. Instead of running 10 pipes in a shaft, you have only one header in the case of VRFs.

There is only one issue in the case of VRFs, which would be the long piping, which could bring up the issue of leakages. So you would need a proper leak-detection mechanism in the case of VRFs. Even here, you can use a simple mechanical isolation software, which as the name suggests, can help isolate the piping zone with the leak. Besides, if the commissioning process is sound, the problem of leakages can be overcome from the outset.

At the VRF Conference we conducted in Abu Dhabi in February, delegates raised the issue of operational data not being available and about how the VRF industry, as a whole, was not showing enough willingness to share information. We received a similar feedback from delegates at a conference in Riyadh in November 2012. Do you see this as a drawback?

First and foremost, VRFs can give you operational data at each zone through wall-mounted controls and PC software. The available features can tell you consumption by the hour and by the zone. Yes, you have to pay extra for measuring, in the case of VRFs, but it is a fact that VRFs give you a better control of buildings on monitoring and measuring than chiller systems.

All that said, in the case of VRF systems as a whole, it is difficult to tell, because there are a number of variables, such as speed, temperature and a varying load all the time. Also, if the outdoor unit is 10HP and if it is connected to 16 indoor units, the COP will vary. If you look at only the COP of the outdoor unit, then you can give the COP. To get a good understanding, perhaps Estidama should say, “If a 10 HP unit, you should use four indoor units of 2.5 HP each.” Also, Estidama should define the pipeline length from the outdoor to the indoor unit. Then, it is possible to define the COP.

As a rule of thumb, you can take a 10 HP outdoor and four or five indoor units of 2 HP each and define the distance of total piping length as 50 metres. And if each indoor is fixed at a distance of 10 metres, you will be able to calculate. I would recommend that this could be considered as the industry standard for measuring COP. In the GCC, we experience very high tropical conditions. We can establish 46°C for the outside and 23°C for the inside.

Also, it is important to remember that no two machines can have the same derating. The length of the coil can change the derating. So Estidama should accept only tested data and not nominal data.

(The writer is the Editor of Climate Control Middle East.)