Friday, 17 February 2017

The high cost of dirty refrigeration coils

It’s every restaurant manager’s nightmare.   Picture the lunchtime rush on a hot summer day in London, your ice machine has stopped working and customers are lined up for their favorite drink. 

Or your reach-in coolers/freezers stopped working at some point last night, and you arrive at the restaurant to find thirty one flavors of ice cream melted.  Food is your business, and food spoilage can mean you are out of business.  Every restaurant manager experiences this catastrophe at some point in their career.  

A major cause of refrigeration inefficiency or failure is poorly maintained, dirty and clogged condenser coils.  

Refrigeration systems are designed to artfully and safely store food products within easy reach, and in most cases, the critical refrigeration components are located within the base of the unit.  These components, including the air intake grille, are at foot traffic level and suck in ground dirt, carpet lint and food ingredients along with necessary fresh air.   

In refrigeration cases, a dirty clogged condenser coil restricts airflow and makes the system work harder and longer, leading to early failure.  In addition, the unit consumes more electricity to maintain optimal food safety temperatures.

Food service equipment can be energy intensive and neglect can be costly.  An EPA study reported that as little as 1mm of dirt on condensing coils will cause a 21% drop in efficiency and can increase refrigeration energy use by 35%.  Another study conducted by Fisher Nickel for the Food Service Technology Center based in California, recently presented their refrigeration unit findings at the RFMA Convention.  Their pre-dirty coil and post-clean coil energy monitoring study (KW/h) at three restaurants reported savings of £225-£450 per year per unit for glass door merchandisers and solid door refrigerators.   

The study also showed that running a 6 year old, 2-door glass merchandiser with clean coils paid off with a 47% reduction (£450 per year) in daily energy use.   According to Tom Scottsman, head of design and development for Arctica Showcases, when a refrigeration case fails from lack of air flow, equipment and refrigerant replacement will cost about £350, plus £75 per hour for 5-6 hours of labour per unit, without any emergency upcharges.  

Refrigeration condensers require regular cleaning, monthly at a minimum.  The condenser tends to be front mounted for easier cleaning access.  Arctica includes a brush with their display cases, and recommends retail staff brush coils clean every 2 weeks.  Preventative maintenance is also recommended quarterly, and costs an average of £75.00 per unit.  Depending on the food service environment, cleaning routines can range from careful surface cleaning in the direction of the fins with a good stiff brush (without damaging them) to vacuuming or blowing the dirt off with an air compressor.  In areas where grease or oils tend to gather on all surfaces, messy chemical cleanings are required.   

All of this is usually attempted within the limited confines of clean, busy food preparation areas.  Although some newer units are designed with slide-out refrigeration systems, others can require proper tools and complicated removal of a metal grille or louvres.  

The logical and most cost effective preventative solution would be to keep the dirt and grime out of the unit after it’s been thoroughly cleaned and serviced.  Top food industry retailers like Starbucks, Costco, Soho and Jewel are finding that they can save time and money by installing a washable electrostatic air intake filter to their new or existing reach-in coolers, ice makers, freezers and refrigerated display cases.    Steel framed with a patented magnetic design is one installation option that allows a custom sized filter to "stick" to the outside of metal air intake louvres; meaning they are accessible from the outside with no need to dismantle the case for frequent coil cleaning.  Retail staff can easily see dust build up on the surface of the air filter.  Each store or restaurant maintains the filters as part of their daily cleaning schedule by removing, rinsing or vacuuming and reinstalling the eco-friendly filters in minutes.   Starbucks NYC regional facilities manager, Bill Miko, found their pastry display cases and ice machines running so much colder with the filter that they were able to adjust the units to lower energy use to accommodate the clean running units.  According to Pete Manuel, property director for Soho Coffee, these air intake filter screens are proving to be very effective in separating nearly all dust from whirling into the chiller components.   An additional benefit is that retail team members are able to remove these filters completely, allowing the dust and dirt to be easily cleaned off away from selling areas and customer traffic.

Condenser coil failure is a costly problem to have and lowers food industry profits.  Not only is product lost due to spoilage, but revenue is hit bylost sales.  Add to that the downtime and cost of an expensive repair bill and you are paying many times over the cost of simple preventative filtration.  Routine maintenance on refrigeration equipment is critical to reduce energy costs, reduce maintenance costs and increase equipment longevity.  So keep refrigeration units clean, save time and save money while you relax with extra whip on your icy cold frothy beverage.

Display refrigeration cooling coil intake impacted with debris.
Dirty cooling coil to floor mounted wine cooler display unit

Dirt impacted air intake fins restrict airflow, leading to equipment failure.

Friday, 3 February 2017

Dirty or clean - your choice

The following picture is a trial RABScreen air intake filter screen after only 2 weeks on trial. The location was south of the River Thames near to London Bridge.
It is an area where not only is there a lot of traffic, but London Bridge Station is undergoing a major redevelopment.
Intake air to these chillers was also drawing in road and construction dust.

As you can see from the zoom it had got pretty dirty at a time when there was no sticky pollen in the air. The benefit of an electrostatic filter screen is that it attracts airborne debris like iron filings to a magnet or in this case dust to a RABScreen.

This particular sample was used to demonstrate just how easy it is to clean by washing it in our kitchenette basin.

A bowl of warm water and some mild detergent was all that we needed together with a scrubbing or washing up brush. The result? A bowl full of road and construction dust.

And a clean filter!

For more information on just how the Permatron RABScreen can PreVent contamination affecting your equipment just speak with one of our advisors by calling

0800 999 5750  

Permatron Corporation. 

Manufacturing quality filters since 1957

Wednesday, 1 February 2017

HVAC Efficiency with Air Intake Screens

Protecting HVAC Equipment Made Easy

      GDF Cofely chiller showing the debris collected       after only two weeks. 
  • Efficient filtration
  • Easy to fit 
  • Easy to clean. 
  • Easy on the pocket. 

HVAC mechanical systems present a variety of challenges to facilities managers and probably cost more than any  other item in the facilities budget. Representing a high percentage of capital costs and operating expenses in repairs, replacements and energy costs, an HVAC system generates an estimated 25 percent of the total energy use in commercial and institutional buildings. Large energy-using systems translate into significant annual savings or losses because they play a critical roll in keeping occupants, data and production processes  comfortable and productive.

Having Performance Issues

Responsible for system performance, Facility Managers struggle to deliver optimal efficiency with preventative maintenance and still balance the budget. Budget cuts and staff shortages force facility management departments to be more creative in planning and prioritising projects. Deferring equipment service may be tempting as a short term solution but leads to greater costs in the long run. Unavoidable environmental issues like air intake obstructions and debris buildup impacts equipment’s airflow and restricts heat transfer. Forced to run for longer cycle times at reduced capacity, operating costs will escalate, breakdowns will occur and equipment life expectancy will decrease.

Debris Clean-Up, Again

A dirty condenser coil reduces cooling capacity (10 ton AC system only provides 7 tons of cooling) and uses much more energy than equipment with clean coils. In areas with vegetation, trees and building sites, repeated cleaning is necessary. Delicate fins and coils require time consuming hand brushing and messy corrosive chemicals that can damage system components and the environment over time. Costly cleaning is especially problematic when there are numerous sets of fins and coils located in hard to reach places or on roof tops without water access.

Let’s look at some numbers associated with dirty coils, which will increase with the number and size of units at each location.

  •  An average coil cleaning cost of £250 per RTU, at a facility with 5 units can add up to £2,500 if done 2x annually
  •  Average energy cost to run a 20 Ton Trane unit with dirty versus clean coils: KWH with clean coils 41,600 – KWH with dirty coils 64,800

Savings/YR @ national average of £0.12/KWH = £2,784

Air intake filtration to prevent damage and blockage of the condenser coils is a simple, cost-effective method of reducing maintenance costs while optimising an HVAC system’s operating efficiency and lifespan. 

Contaminants like grass cuttings, insects, seedlings, dust and dirt are captured before they enter the system, and quickly brushed clean with a broom. Permatron’s PreVent® air intake screens are custom manufactured for each application, ready in just days for easy installation and fitted to the individual equipment. 

Want to know more? Call 0800 999 5750 and talk to one of the team.

Article courtesy of Permatron Corporation. Manufacturing quality filters since 1957

Friday, 9 December 2016

The RABScreen in action for the NHS

Air filtration is receiving a lot of press at the moment. Air quality in general and indoor air quality in particular have been talked about in many trade magazines and publications. 

The London Assembly published “Air Quality and Health” in which they discussed airborne particulates and the resulting “concentrations of air pollutants and how these affect health.

The majority of commercial office and public buildings (hospitals. Universities, schools etc.) will be thinking that their equipment is protected from the damaging impact of these pollutants. 

All modern air handling equipment will contain banks of filters, specified by the manufacturer to meet regulatory demands. This does NOT mean that they are the most efficient filter available and air filter suppliers are looking to replace this lower cost product for one that works more efficiently.  

These filters will generally be more expensive than the original equipment specification but they will provide much better protection against the smaller pollutants. 

RABScreen are working to protect the disposable filters by taking larger particles from the airflow. This allows the more efficient product to do its job for longer saving both time and money.

Also, the RABScreen will protect cooling and heating coils by reducing the impact of the airborne debris that causes coil clogging. 

An intake plenum at Bristol's Southmead Hospital now protected by a RABScreen.
A RABScreen air intake filter screen at Tewkesbury

 AHU supply air intake at Tewkesbury Hospital. Cleaner air and improved filter life with the advantage of frost coil protection.

Clogged coils increase the energy required to meet design criteria as the fins need clear, unobstructed airflow to work effectively. Typical ROI for coil protection is less than 6 months with additional savings from reduced labour and chemical use.   

It is a win, win situation.

  • Better disposable filtration = improved indoor air quality.
  • Additional external filtration = labour, time and energy savings.

Richard Betts
RAB Specialist Engineers Limited

Thursday, 20 October 2016

Energy Savings

All occu­pied buildings have teams of people who know everything about how the building works, right? 

Wrong. There are likely to be only 1% of facil­ity managers who actually know their building’s energy systems in detail. Most people who work in the building are only interested in “Do the lights work?” and “Is anyone complaining?”

Facility teams are expected to be knowledge­able but 99% don’t pay close attention to energy; there are too many plugged toilets, leak­ing roofs, rooms that need cleaning, lights that need lamps, new offices to partition and a never ending list of other demands from the Building Occupiers. ASHRAE’s Procedures for Commercial Building Energy Audits is a thorough resource for the information needed to understand an existing building’s operation and at only $109 is a great place to start.

  • Do you have a leaking envelope due to poor exterior caulking or faulty HVAC dampers?
  • What about the toilet extract fans? Are they running 24/7, especially when the air han­dlers are off at night
  • Do you run the building HVAC system manu­ally, making changes based on temperatures, expected weather conditions, occupier complaints etc.?
  • How many air and water controls have been adjusted from the original design set point.
  • Do you have a new tenant who works 16 to 18 hours a day and uses equipment way over original design duty?

Many buildings (most, it seems) are giving minimal attention to mainte­nance. HVAC problems are often ignored until they become major, so it’s well worth the time to carefully inspect and assess the cur­rent operation.

If you haven’t considered that fact lately in the context of buildings, think about why you take your car in for a service or why you visit your doctor for a check-up or why you mow the grass, for that matter.

Buildings are no different, but somehow are perceived differently when it comes to ongoing maintenance.

Let’s face it the common “preventive maintenance” contract is a bare minimum scope of work with no time devoted to evalu­ation of performance apart from filter changes, bearing lubrication or equipment that’s obviously not working.

Energy saving ideas should be driven from the maintenance team upwards. Unfortunately, the people with most knowledge of the building have the least time to undertake this function due to the short change contract they are working to.

If you are interested in solving your energy usage then resist the pigeon hole method in which you start with your energy bill which is then distributed into smaller pigeon holes based on CIBSE values for the fans, pumps, light­ing, cooling, heating, floor power, domestic hot water, etc.

This approach has no pigeon hole to represent wasted energy, even though it could be as high as 30% of the total energy use.

Consider the following situations as examples of what you may be unaware of.

  • BMS incorrectly calibrated or working with old technology with little trending data.
  • Pipework is not insulated wasting both cooling and heating energy.
  • Valves have had their insulation removed but not replaced. 
  • Pump motors are not controlled correctly. A booster set will pump on demand no matter how low. This results in a 3-minute cycle and most of that time will be against a closed valve.
  • Lift shaft damper open creating a high velocity 24/7 chimney causing the core to cool rapidly and the HVAC to start early.
  • Check AHU economiser locations. Is it located on a south facing enclosure seeing 23°C in the sun when it is really 16°C, forcing all AHUs to minimum outdoor air and full me­chanical cooling.
  • Is the economiser changeover set point 13°C instead of 21°C?

If the site inspection is hurried or hampered by time and budget constraints then, you cannot evaluate the building in enough detail to understand operations.In a full 48 hour inspection of one building the engineer discovered:  

  • Pumps running 24/7 or not running at all.
  • Fan motore running but not driving fans. 
  • Booster sets running against closed valves.
  • Pneumatic controls faulty, fan coil motors failed and signals from economiser incorrect. 
  • Pipework, valves and ductowrk uninsulated. 
  • Strainers clogged. 
  • Chiller compressor failures
  • Filters clogged or missing 

Each one of these problems should have been picked up and actioned during a full site inspection or PPM walk around by the resident maintenance engineer. 
The building occupier’s method of curing heating and cooling problems was to install new AC units because the staff were complaining “Most people who work in the building are only interested in “Do the lights work?” and “Is anyone complaining?”  Short term solution to long term issues.

Following all of the repair and upgrade work the energy bill dropped by more than 25% and the money spent was recovered in less than two years. There was nothing glamorous about any of the work orders received and each one varied in cost and ROI but the overall result was reduced carbon footprint and happier staff. Apart from the resident maintenance engineer who now works in the post room.

It is a similar situation with the RABScreen external filters. Small value projects with high ROI and brilliant energy saving. If you don't know what a RABScreen is just click to find out more.