Cleaning airxchange wheels – Sterling ERMS User Manual

Page 12

Cleaning Airxchange Wheels

and the ability to soak the individual segments clean

so that the need for cleaning is less frequent.

An alternate to cleaning is the periodic replacement

of dirty segments. This can be economically

advantageous when both labor costs and energy

costs are rising.

Recommended Cleaning Procedure

Access the energy recovery wheel and remove the

energy transfer matrix segments. (For one-piece

wheels 25 inches in diameter and smaller, remove

the wheel from the cassette.) First brush the wheel

face to remove loose accumulated dirt.

Wash the segments or small wheels with a non-acid

based (evaporator) coil cleaner or alkaline detergent

solution. Non-acid based coil cleaner such as KMP

Acti-Clean AK-1 concentrate in a 5% solution has

been demonstrated to provide excellent results. Do

not use acid based cleaners, aromatic solvents,

temperatures in excess of 170

F or steam;

damage to the wheel may result. Soak in the

cleaning solution until grease and tar deposits are

loosened. An overnight soak may be required to

adequately loosen heavy deposits of tar and oil

based contaminants.

Internal heat exchange surfaces may be examined

by separating the polymer strips by hand. (Note:

some staining of the desiccant may remain and is not

harmful to performance.) After soaking, rinse the

dirty solution from the wheel until the water runs

clear. Allow excess water to drain prior to replacing

segments in the wheel or reinstalling the wheel in the

cassette. A small amount of water remaining in the

wheel will be dried out by the airflow.

Last Reviewed 6/28/06

Overview

All air-to-air energy recovery devices will get dirty

over time, even with well-maintained filtration. One

advantage Rotary wheel technology has over fixed

exchangers is the ability to ‘self clean’ of dry dust and

dirt by rotating between two opposing airstreams

traveling from 500-800 fpm. In wheels with laminar

flow matrix designs, this self-cleaning feature works

well until the wheel is exposed to oils, tars or greases

in either the supply or exhaust air streams. Once

these pollutants deposit on the rotary surface they

become ‘sticky’ and begin to attract and hold the dust

particles that previously passed thru the wheel. Over

time this particle build up can lead to blocked airflow

passages, loss of recovery, excessive pressure drop

through the wheel and loss of energy savings.

Field experience shows that offices, schools and

other ‘clean’ environments will often go 10 years

before any build up of dust and dirt is noticed.

Restaurants, Casinos, factory environments

experience fairly rapid build up of contaminants and

require multiple cleanings a year to maintain airflow

and recovery.

Field experience also shows that all rotary wheels will

experience some degradation of latent recovery, long

before they appear to be plugged. While exhaust air

contamination is the primary source, local

environmental conditions can contribute. For

example units located near heavily traveled

expressways or downwind of fast food restaurants

may experience measurable loss of latent

performance within 3-5 years of operation.

Airxchange wheels are manufactured to be easily

cleaned outside of the unit. The benefits include

elimination of a drain pan in the wheel section of the

unit and associated IAQ problems, the elimination of

the need to drag a pressure hose to the unit on a roof

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