Air Handlers are manufacturers of Heating, Ventilating and Air Conditioning Equipment for the building services industry

Air Handlers Celebrating 30+ Years of Success 1989 - 2024

Site Services

Air Handlers Northern Ltd provides a comprehensive portfolio of sitework options to assist contractors and end users, together with a factory testing facility can offer certified performance tests.

The range of site services available to our customers is detailed below: -

Flat pack AHU site build

As remodelling of buildings becomes more predominant in the construction industry access into the building for replacing AHU plant becomes more complicated than with a new build. Air handlers have completed hundreds of site build flat pack installations over the years, the largest site build project completed in 1992 at Proctor & Gamble Trafford Park Pampers Nappy manufacturing plant. The air handling unit was an external weatherproof. The air handling unit has overall measurements of 5 metres high x 10 metres wide x 20 metres long. The airflow was 72m3/sec and comprised:

  1. Return Fan
  2. Mixing Chamber
  3. Pre filter chamber
  4. Spray humidification section
  5. Bag filtration
  6. Cooling coil section with eliminators
  7. Heating coil section
  8. Supply Fan
P & G Unit GA DWG

This air handling unit is still in full operation working 24/7 with very little down time.

Another major project completed by Air Handlers Northern Ltd was at 2-12, Baker Street, London in compliance with an overseeing design brief by Caldwell consulting. The Air handling unit was built in the basement of the building with very limited access. The air handling unit and components were flat packed on pallets and lowered into the building basement, then manoeuvred into the plantroom.

Flat pack build projects start with a site inspection to evaluate the lifting, access equipment and flatpack pallet maximum size. Upon understanding the restrictions and limitations of the site and location a method statement together with health and safety documentation is issued for comment and approval.

On approval of the RAMs then flat pack manufacture will commence. An overall general arrangement of the air handling unit will be also issued for approval together with any controls/component requirements needing customer approval.

Successful flat pack installations happen when the contractors on site manages the area where the flat pack build will be taking place, also space allowance must be allocated for the pallets containing the flat packed components.

The contractor must make sure that the main contractor or other sub-contractor(s) do not use the designated areas for storage of their materials. If the site build area is not managed by the contractor correctly then Air handlers Northern Ltd will not be responsible for any damage, moving of other contractors’ materials, delays due to poorly managed flat pack space by others.

Air handlers site services operatives used will be fully trained by the company, will hold all relevant accreditation. The company also understands and incorporates the time required for health and safety site inductions.

It is essential when considering HTM-03 /NHS Hospital Specification refurbishment works that a specialist manufacturer/supplier is used and employed to give qualified advice.

Provision of RAM’s is essential to fully describe the scope of works and health and safety requirement statements. All materials used in the refurbished air handling unit proposal must be stated in the scope of works. Materials offered must be HTM-03 compliant.

Stated below is a chart of hospital quality air handling unit age verses related hospital specification.

Plant Age

Probable Specification Build

2 years

HTM-03 & ERP 2018

2-4 years

HTM-03 & ERP 2016

4-13 years

HTM-03 & ERP 2009

13-20 years

CO4 NHS Specification with limited energy recovery

20-30 years

DV4 with limited hygienic standards

For older plant built to CO4 and DV4 NHS Specification it may be a consideration if a major plant refurbishment is required that a full replacement is the best solution to the latest HTM-03 and ERP directives, however care must be taken due to the increase in size for a replacement.

Refurbishment of Air Handling Unit

The General life span of an air handling unit will vary from 20-35 years depending on the original quality of construction and the materials used in its construction, together with its location.

Components within the air handling unit will also vary in life span. Items such as aluminium finned coils, aluminium profile dampers, fan motors and cooling coil sections.

The refurbishment of an air handling unit should only be undertaken by qualifies experience companies with specially trained HTM-03 NHS Specification engineers.

Inspection of air handling units in the Hospital/ Pharmaceutical environment should be done again by qualified engineers to assess the required upgrade of the air handling unit. While refurbishment of hospital HTM-03 air handling units may be considered exempt from HTM-03 guidance specifications, the same may not apply to ERP laws.

The refurbishment of the existing air handling unit casework. Replacing like for like components can constitute repair/ maintenance. But if the fan(s) in either the supply or extract fan sections are replaced then frequency inverters must be fitted if they are not.

Performance Testing

A specialist test area in our facility can facilitate testing of air handling units with airflows of up to 30m3/sec or 200 Amps per phase maximum. Our test facility can simulate airflow, power consumption, controls function simulation, leakage rate testing, coil hydraulic testing, refrigerant tightness, acoustic breakout testing to NR50 minimum.

Acoustic testing below NR50 will be difficult due to external threshold ambient conditions. To Achieve this, attenuators will need to be supplied by the contractor for insertion into the test rig.

Once the air handling unit under testing achieves its correct volume/pressure then sound pressure and sound levels can be taken. Air Handlers Northern Ltd test area is certified for reverberation condition and allows correction of reverberation time values to give correct sound pressure values.

Witness testing with the client, client representatives, commissioning engineer presence is a regular occurrence. Witness test results are tabled on the day of the test and signed for conformity. A full test report with instrument certification will be issued as part of the documentation process.



Flat pack air handling unit delivery for Putstar Rochdale

Leakage Testing

Certified leakage tests can be carried out in the factory or on site. Air Handlers Northern Ltd engineers fit the required blanking plates to the air handling unit being tested, connection and hose is also fitted prior to the test by our operatives.

When the leakage test machine records the correct test pressure it is then allowed to run for 30 minutes to show the test results continuity.

After any leakage test a report is issued with photographs showing the apparatus working and the pressure/leakage rate achieved. In the case of large air handling plant more than one test machines may be needed.

AHU Site Bolting of Sections

A Bolting together service is offered when air handling units are delivered in sections.

The company always recommend its fully qualified operatives build and seal the air handling units if delivered in sections. The correct sealing methods and section clamping arrangements must be used to prevent excessive air leaks.

Contractors often use ductwork installers or their own operatives to bolt the air handling unit sections together and often airt tightness is compromised which can reduce the plant life span due to water ingress on external air handling plant.

Contact our sales department on +44161 745 8888.

Component Commissioning

Specialised components such as controls, humidifiers, gas burners, thermal wheels should be commissioned by a trained commissioning engineer preferably from the equipment manufacturer.

Commissioning reports will be issued and included in the OEM documentation.

When arranging the visit of a commissioning engineer to visit site it is normal practice to send to the contractor a “pre commissioning questionnaire” which will outline the site requirement to be enabled prior to the visit such as.

  1. Power on to the control panel
  2. Gas supply on to the gas burner at the required pressure.
  3. Power and controls signal to the humidifier.
  4. Waste pipework to the humidifier with correct trap installation.
  5. Power and controls signal to the thermal wheel
  6. The air handling unit is cleaned out from site debris.
  7. Access to all sections of the air handling unit are to be confirmed.
  8. It is often required that controls or BMS engineer is present at component commissioning.
  9. On cooling coils & exhaust run around coils the correct trap and drainage pipework must be in place.

Commissioning of Skidpak and Envirofresh packaged heat pump units are preferably done in the factory to check for the following.

  1. Fan rotation direction and balance checked.
  2. Controls function tests.
  3. Refrigeration pipework, valves, compressor refrigerant gas soundness.
  4. When the refrigeration system is leak tested and passed for soundness a holding charge is left in the system.
  5. Compressor speed variation and fan variation is checked via the 0-10 volt signal variation.
  6. On runaround coil systems the pipework is fully vented.

In the case of site build Envirofresh and site installed refrigeration pipework. Leakage soundness and functional tests will be carried out on site.

When Skidpak and Envirofresh Units are factory commissioned, it will also be required that final site commissioning is done after airflow balancing, the final refrigerant charge is applied to the correct refrigerant pressure for each circuit.

It must be noted that heat pump commissioning is difficult if the atmospheric temperature conditions are not clement.

Site Inspection of Existing Air Handling Units

Air Handlers Northern Ltd offer a site inspection service to review the condition of its own products and other manufacturers products.

Advice is offered should refurbishment or upgrade works are being considered, a report can be submitted giving an unbiased view of the condition with options for client consideration for repair, refurbishment, complete replacement. This report can offer budget costs for the options put forward.

For further information contact us on +44161 745 8888

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