High Performance HVAC Air Handlers

ECM Variable Speed Blowers

Variable speed blower motors have become increasingly popular in residential air conditioning and heating systems and for good reason; these motors increase efficiency of the systems and offer a whole range of other benefits that help the system and the consumer.

Variable Speed Blower Motors first offer a higher efficiency for air conditioning systems based on the manufacturers set up of the control with the ECM Variable Speed Motor. Each manufacturer calls it a different thing such as Trane calling it the Comfort R and Carrier calling it Infinity Control. Despite what the manufacturer calls it helps efficiency with air conditioning by starting the blower slowly and letting it run at a 50% speed for the first few minutes (up to 7 minutes) to remove more humidity. This increases comfort and efficiency by removing more moisture from the air. The lower the humidity in the cooler you will feel so the variable speed blower with this type of control will enhance comfort.

ECM variable speed motr manufacturers include General Electric and Emerson with Emerson offering their very own packaged control and control program to meet various control sequences to meet efficiency and comfort for any manufacturer that uses the Emerson ECM variable speed motors for their equipment.

Other benefitss include:

Soft start capabilities which reduces high inrush current like conventional blower motors.
Precision control to deliver a set amount of CFM’s for whatever the HVAC equipment manufacturers need for their equipment for airflow control.
High efficiency which reduces energy bills.
Very quiet operation
Better comfort as described above

One of the disadvantages include a high replacement cost if something happens to the motor or controls. ECM variable speed motors need the attention of a qualified HVAC technician if something goes wrong as special diagnostic tools are needed to diagnose any problems which may arise with the motor or controls.

These motors are typically offered in the medium to higher end models of air handlers and furnaces so you will have to pay a little more for the initial cost but the benefits will give you a pay back in the future with increased comfort and higher efficiency. Here at High Performance HVAC we always recommend going for higher efficiency models because the cost of energy is not going to go down in the future and the high efficiency models will help reduce the cost of energy so your utility bills will be reasonable in the future. The bonus this air handler or furnace component also adds comfort while increasing efficiency.

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ECM Blower Motors

How do I find out the tonnage on a AHU? The label/tag has faded all I have on file is the model number and the serial number, make.

Question Posted By Francisco the Building Engineer on May 3, 2011

Refer to the manufacturers website for their HVAC nomenclature of model number and serial numbers and how those numbers correspond to the tonnage and other technical data. Or you can call your local dealer for the manufacturer and they will tell you.

If you use the website route then be prepared to decipher the model number from the HVAC nomenclature chart which the HVAC manufacturer probably has in PDF format for download. An example of a nomenclature chart for HVAC equipment is below:

nomenclature HVAC equipment and components

In your case you will want to see number 5 for your reference if you had this type of HVAC equipment which correlates to Unit Size in MBtuh. HVAC Nomenclature charts are not only available for HVAC equipment but also some HVAC components such as compressors, motors, and other HVAC components. These nomenclature charts are used extensively in engineering including HVAC and science to decipher lists and sometimes to keep things simple and orderly even though the layman may not see it that way. The origin of the word goes back to the Roman days where a steward commonly referred to as a nomenclator has a system of naming and would maintain a catalog of political names so it is most likely completely derived in Latin.

There are some pieces of HVAC equipment that may not or will not have any nomenclature type model numbers attached to the air handler or the HVAC equipment. These are usually modular units that are assembled on the job site and typically applies to large air handlers and other types of modular equipment that is very large and field assembled. To find the tonnage information along with other pertinent HVAC data find the final stamped set of drawings for the job. The final stamped set of drawings are stamped by the design engineer who is supposed to be a P.E. or a licensed Professional Engineer. If you look at the schedule usually in “M” drawings for mechanical you should be able to find the equipment as installed by the mechanical contractor and approved by the engineer. One other way to determine the size of the equipment if you can find all the drawings and paperwork for the job is to find the TABBs report. Sometimes the equipment size and sizing calculations are noted in the TABBs report. In the TABBs report you can also go by the airflow amount and divide by 400 E.G. an air handler that has a capacity for 1200 CFMs is a 3 ton unit.

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ECM Blower Motors

ECM Variable Speed Blowers

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Find Tonnage on AHU – Equipment Nomenclature

Find Tonnage on AHU – Equipment Nomenclature