Ability will be refitting their London Showroom. This is used to showcase and demonstrate its ranges of Fan Coil Units, Heat Recovery Units and Twin / Single Fan Units. It will also be used for training and CPDs. The facility itself is...

World Projects

FCU Refurbishment and EC Upgrades in More Depth

Never has the refurbishment of existing fan coils been so ‘in vogue’ and so important. Refurbishment of course, usually means new fans, motors, filters and sometimes new controls, in combination with an overhaul of the heat exchange coils and chassis. The easiest way to understand why this is now a highly cost effective and very viable alternative to full fan coil replacement, is to examine the reasons that made refurbishment impractical until very recently.

Older AC fans have always been problematic to replace because of the mechanical variability of the large number of types available. For example, we had the AC ‘fan deck’ format in which a single motor could be driving one, two, three or even four fans. There was also the external rotor/motor format where each fan was driven by its own integral motor. Furthermore, these two types used either tapped wound motors or tapped wound transformers along with a complicated and ‘manufacturer specific’ wiring loom and switch assembly. An understanding of this terminology is not important, the point is that AC fan decks could and did, come in a ‘never ending’ variety of styles, sizes and configurations.

So, in order to initiate any fan coil refurbishment programme, it was first necessary to find the replacement parts -- potentially 15 years after the fan coils were manufactured! This was always particularly difficult with regard to the tapped motors or tapped transformers, speed switches and looms. The reality was that for most viability studies, this lack of cost effective or alternatives parts was not simply a problem – it became the ‘show stopper'.

Fancoil-Controls

 

'Its simply not practical to replace or refurbish controls this complicated 15 to 20 years after they were supplied'

 

And what about replacing the controls? Most fan coil units (including Atholl FCUs) in the last 15 to 20 years have been fitted with either stand-alone or communicating type controllers of one flavour or another -- Siemens, Satchwell, Danfoss, Staefa and Johnson to name but a few. In terms of communication languages (protocols) we have seen Batigyr, Lonworks, Modbus and a myriad of others. Once again, the problem has been finding current parts to replace older and often, discontinued items.

Finally, the reason most refurbishment feasibility studies eventually fell at the first fence was that, even if by some miracle it had been possible to physically recreate an new fan coil 'Look Alike', apart from giving the units a few more years of life, what was the point, especially as the exercise would probably cost more than a whole new set of fan coils.

Fan Coil for Refurbishment

 

'In need of a little Attention'?

 

 

 

So, what has happened to make these problems disappear? Quite simply the introduction of EC/DC fan and motors sets. New EC/DC fan motors are of a size and performance characteristic in complete sympathy with the majority of fan coil units, past and present. But this is just the beginning.

The latest EC/DC fan motors all have a built-in 10Volt output, which can be varied or adjusted with nothing more than a rotary potentiometer. After passing through the potentiometer, the modified voltage is sent back to the motor and dictates fan speed. Generally, up to 2 Volts is considered off and from 2.5Volts to 10Volts gives infinite and step-less fan speed and therefore, air volume adjustment. The point here is that a potentiometer costs practically nothing but removes the need to design and recreate a transformer and switch assembly that could very easily cost more than £20 to replace.

EC/DC motors are now accepted as being far more energy efficient than their earlier AC counterparts. Using an EC/DC motor as a direct replacement, in other words in a fixed speed mode at the same duty point, will save 50% of the electrical consumption of any fan coil. Whilst most projects stop here, it is also possible to apply a variable speed strategy based upon demand, occupancy or both, which will enhance savings still further to the order of 80%.

As regards a potential project therefore, what then would be the routine? Firstly, a survey will establish the condition of the existing units, the controls and ascertain what the client wishes to achieve from the exercise. Normally, basic refurbishment includes the complete replacement of the original fan decks with new ED/DC types (including the speed adjusting potentiometers), vacuuming or replacing the filters and a general clean and inspection of the unit, including its condensate trays and condensate lines.

If in replacing the fan decks, the requirement is to set new decks to the same air volume as the old AC fan decks, a quick intake air velocity profile conducted before the changeover indicating the benchmark against which the new decks must be re-tuned once installed. All old fans, motors and other redundant equipment are removed and recycled.

Another problematic component can be the valves, which over time may have become blocked or seized. Also, the valve actuators may have ceased working or become physically damaged. If the valves are in this condition, it can be quite cost effective to replace them with more modern components and at the same time, change the terminal controller to a BACnet, open protocol device. Open protocol not only keeps the parts ‘competitive’ but also allows the introduction into the refurbishment process of variable speed, demand dependent fan speed strategies. These strategies vary the fan speed of the unit in sympathy with the current demand and can also put any fan coil into a ‘sleep mode’ when a building, or floor or office space is unoccupied. As mentioned earlier, this approach can reduce the fan coil system electric consumption by 80% almost overnight and goes a long way therefore, to help finance the whole project.

On the basis that a fan coil has a life span of say 20 years and the UK has consumed say, some 60,000 UK manufactured fan coils per year over that time, it means that a million plus fan coils are in circulation with many either approaching or indeed past their planned lifetime. While many will of course, be replaced completely, the advent of EC/DC refurbishment has now opened up new opportunities in cases where money, time or disruption demands a viable alternative.

Visit Palestra, an EC upgrade project

Visit Winchester House, another EC upgrade

Visit The Ark, Hammersmith, another EC upgrade project

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