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Spotlight


DearEditor I


Martin Procter, Swegon’s product manager has a different point of view following our recent feature in our February issue. This is how he sees it …


read the ‘Fan Coils vs Chilled Beams’ article in February’s issue with interest. This issue is quite a hot topic with the current drive on energy efficiency, and it is very important that both sides are represented. The article correctly states that fan coils have an ‘on board’ fan motor,


A Remeha technical meeting


individual project. Clearly there is a place for all technologies, and this is an area where Remeha as a manufacturer can, and does, add value. Firstly the company offers a carefully selected, fully-


complementary product range. The gas-fired CHP units and gas-driven heat pumps, coupled with reliable and efficient gas condensing boilers, create excellent energy-efficient solutions that are proven to benefit specifiers, contractors, end users, and the planet. Crucially, Remeha also offers the expertise to optimise the


real-world operation of these hybrid systems. Good design, integration and control – not forgetting commissioning – are essential to maximise the overall efficiency of a system and achieve the predicted energy performance. Expert sales managers not only offer in-depth product and technical knowledge, but they major in integrated design. Working closely with specifiers and consultants, they support them in ensuring that the best mix is presented to the client, leading to the most energy-efficient system each and every time.


Putting the user in control


Heating manufacturers have long recognised the importance of good controls to optimise individual boiler performance and overall system efficiency. But improving the way end users interact with controls has proved an extra hurdle for the industry. Following extensive research, Remeha has created its new Ace control platform design, as featured on its Quinta Ace 160 and Gas 220 Ace models. The Ace control is designed to be both simple to use and robust with tailored information available for our target groups – heating engineers and end users. Two entry levels from the larger, enhanced screen, can enable both groups to access easily the right amount of information at the right time. The company predicts that this pioneering control platform will be more likely to be used effectively, for improved energy use and management.


Future plans


In unsettled times of changing government rhetoric and unclear energy policies, Remeha actively works alongside industry bodies, pushing for an increased drive for improved energy efficiency, and financially and environmentally sustainable development. The overriding aim is to continue to innovate with advanced heating technologies that will support customers, businesses and society – regardless of political change. With the growth of mixed-use developments and localised heating schemes, Remeha sees the combination of its traditional condensing boilers and CHP units in heat networks as a major factor in the years ahead.


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whereas active chilled beams use pressure generated by the central AHU plant, and goes on to give figures for fan coils and states that the additional power requirement for a chilled beam system is “not dissimilar to the total fan motor power of the fan coil units”. The specific figure quoted for fan coils is that an SFP of 0.15w/l/s “can” be achieved due to EC motors (which of course would also be used in the central AHU plant, similarly enabling central plant on a chilled beam system to be run efficiently and on part-load demand control if required). I do not question the 0.15w/l/s, however, for the suggested total fan energy of less than 0.3w/m2 delivering an air volume of 2l/s/m2 ing ∆T, this would deliver 24w/m2


this would mean the FCU


. By my estimation, at a typical 10K cool- of cooling, which would seem to me a low


requirement for a ‘typical’ environment requiring secondary terminal unit cooling. Perhaps a more accurate cooling requirement would be something like three times this, i.e. 72w/m2 more like 0.9w/m2


, so fan energy would, in my opinion, be . To compare that to the total fan energy for the active


chilled beam system we would need to know the increased SFP of the central AHU. As a rule of thumb an increase of 100Pa to the external static pressure would equate to an increase in AHU SFP of up to 0.3w/l/s. So whilst on the face of it an apparent increase in SFP versus the FCU 0.15w/l/s claim, it must be remembered that the AHU is delivering only primary fresh air, so typically 1.5l/s/m2 with one person per 8m2


. So additional primary fan energy required to


‘drive’ the chilled beams would be around 0.3w/l/s x 1.5l/s/m2 = 0.45w/m2


, assuming a typical 12l/s per person .


Or approx 50% of the fan energy of the fan coil. Chilled water: The article suggests that if 10/14˚C were used with fan coils and 14/17 with chilled beams there is “a small difference in energy consump- tion between the two systems”. Again, rule of thumb, but every degree rise in CHW flow temp would equate to around 1.5% improvement in chiller efficiency. So from 10˚C flow temp (if we accept the veracity of this as a typical FCU chilled water flow temp) to 14˚C, 4K difference x 1.5% = 6% improvement in efficiency. There would of course also be the chiller size to consider; the higher the chilled water temp the greater the output of the chiller; rule of thumb again, but 2.5% increase in output per ˚C rise in flow temp, so 4K difference x 2.5% = 10% more output from the chiller, or chiller 10% smaller if you prefer. And this before we consider the huge additional benefits of free cooling, eminently viable at typical chilled beam flow temperatures of 14˚C or above, but much less so at typical FCU flow temperatures. The article also mentions that “virtually all chilled beams are cooling only”. Unfortunately, as a chilled beam manufacturer my experience is the opposite, “virtually all” active chilled beams that we supply in the UK are cooling and heating, and do an admirable job despite the article’s claims to the contrary. Many times the same misnomer has risen its head with consultants or clients who have been misinformed, and many times have we performed witness tests for heating, and on all occasions, have received complete acceptance. Flexibility: The article seems to be comparing fan coils with multi-service


beams, which are different propositions. A fairer comparison of flexibility would be fan coils with 4 way modular chilled beams, a growing market in the last 10 years or so. To the architect or end client, their appearance would be very similar to a fan coil system, with the comfort modules being a tile replace- ment format, and in terms of flexibility, with air volume and direction individu- ally adjustable on each of the four sides, would offer much greater flexibility. And with the same modular format as fan coils, no issue at all for partition splits to be erected between, indeed without the need for any mechanical adjustments mentioned, such as “blanking/moving/activating diffusers”. Cost: I don’t believe the carbon emissions are similar, so even if a chilled beam system were to cost more to install, the payback is quick and life cycle savings significant. When the full capital cost of the systems is compared the difference between systems should not be significant enough to preclude the future life cycle savings available by using chilled beams. We can agree the UK fan coil market is currently larger than the UK chilled beam market…but I suspect we might have differing views on how this will look in a few years time with the continuing focus on system efficiencies. Want to hear the other side? Advanced Air puts the case for Fan Coil Units in our February issue on pg 30 bit.ly/2lUG9Cu


May 2017


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