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Case Study: Chiller Repair & Refurbishment

Repairing and Refurbishment Rather Than New Equipment - ThermOzone

Woolverstone House, Berners Street, London.

ThermOzone recently revived a tired but otherwise sound Water Chiller serving a prestigious but small building in London's West End. The result for the client has been remarkable.

woolverstone house2

So is all equipment at the end of its service life, just because it is old?

OK, not all equipment can be brought back and made serviceable again. BUT, those that can should be. Firstly bring it back to its original design operating specification and then apply today's technology, and them some!

Our example is a site like many others the water chiller serving the air-conditioning has provided a sterling 27 years service, but was suffering the affects of its age, with a broken, but original screw compressor. Indeed many lesser chillers would have given up years before. But remarkably the remaining major sub-assemblies were all in sound condition, just a little rust patch here and there, and jaded around the edges.

Due to its location to change the chiller to a modern 'throw away' unit offering - 8-10 years service life would have cost the clients ...£40k, or considerably more if a disruptive multi split system were installed throughout the building, as was being considered. Plus the problem had been overlooked through the recent Winter, leaving little time to have a new chiller or entire system delive red in time for the Summer cooling season.

Initial assessment

Original Chiller - Hitachi 85 kW from 1990

Original Chiller - Hitachi 85 kW from 1990

First task currently can it hold the load of the building, what needs to be changed and what design elements can provide an advantage, e.g. energy savings?

In this case the condenser coils are fine, the evaporator vessel is fine, the fans are all working, and the structure is sound.

Logistically what access is there to move heavy equipment from ground to roof. In this case there was only a sky light access which proved challenging.

 

Secondary Assessment

woolverstone house4

Select equipment that will match the overall requirement for the desired capacity, primarily the Compressor with matched Inverter, then design a Controls system layout to provide proper efficient control, an Electronic Expansion Valve as primary system control.

In view of its age, a basic repair was clearly not going to work reliably, so we produced a re-design to appoint a new screw compressor with inverter drive, allowing us to select the most energy efficient refrigerant, indeed a refrigerant that will allow further upgrade in the future when HFCs are phased down, plus the chiller can achieve the highest levels of energy efficiency, otherwise found in far larger turbine based and often overly complex systems. This also required replacement of the ancient electro mechanical controls to a modern set of electronics that can properly control the entire chiller’s functions.

Sounds expensive, well here’s the sums…

The chiller concerned is a nominal 85 kW capacity.

woolverstone house6

  New Chiller ReChill Concept
Buy  £20k £23k
Remove Old/Install  £15k £n/a
Connect  £5k  £n/a
Set to Work  £2k  £ included
Project Total  ~£42k  £23k
Carbon Trust Funding  £0  -£7k
Net Project ~£42k ~£16k
Life Expectancy ~ 8 - 10 years 10 years +
Project Implementation Period ~ 12 weeks 4 weeks
 

So this is what £23k and some ingenuity can buy — you do not have to have road closures, cranes nor 12 weeks delivery, and if in London a 3 month wait plus a planning bill for a road closure. Including the inverter reduces your energy bills up to 70%, inclusion of RODEM remote support facility allows us to provide a a 50% reduction in service visits and a 24 hour 7 day week monitoring and support. All with a longevity expectation better than the new option being considered.

woolverstone house5

The finished project Chiller - the RODEM aerial can be seen sitting on top of the chiller to the left side

The project here is a reality and has been completed and is running superbly. The installation took just 4 weeks. The principle for this 85kW chiller applies equally to a 1,000kW unit. These sites exist all over England and as a Carbon Trust Accredited Supplier we can approve the above project for a direct funding grant contribution of 30%, reducing the Clients actual bill to just £16k.

The reduced energy usage provides ongoing revenue savings benefits for the service life of the chiller, way beyond the predicted payback of just 3 years.

© Article by Trevor Dann - ThermOzone Ltd - May 2017

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We can supply, repair & remanufacture all the leading makes of compressors, chillers, air-conditioning & refrigeration units found throughout the HVAC industry.

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