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Economizer Types Defined

HVAC Economizer Types Defined MicroMetl Feature

Nancy Chen - MicroMetl Design Engineer

Nancy Chen

Economizers are mechanical devices used to make the Heating Ventilation and Air Conditioning (HVAC) unit more efficient by regulating the return air and outside air. Economizers come in many different configurations.Low Leak Ultra Economizer Micrometl

Low Leak is defined as an industry requirement permitting a minimal quantity of air leakage aka CFM through closed dampers. Any leakage within those limits are referred to as “Low Leak.


Standard Leak economizers are not as tightly designed as “Low Leak” and allow more leakage. They would not meet the industry requirements for “Low Leak”.

Low Leak Economizer MicroMetl

MicroMetl Down Discharge Economizer (ECD) series are designed for vertical/down discharge HVAC units. The economizers fit inside the HVAC unit and over the return air opening located on the bottom of the unit. All economizers are equipped with horizontal gear driven blades.  Economizers are normally equipped with a gravity relief damper (Barometric Relief). The ECD series economizers come in low leak and standard leak.


Horizontal Discharge Economizer


MicroMetl Horizontal Discharge Economizer (ECH) series economizers fit inside the HVAC unit and are used in the horizontal application. Due to size constraints and the opening location, the blades are vertical. Ductwork connects to the horizontal return air opening. ECH series economizers are available only as “Standard Leak.”


External Mount Economizer


The MicroMetl External Mount Economizer (ECE) is designed to fit within ductwork or attached externally to an HVAC unit. The ECE series economizers contain separate dampers mounted on the outside of the HVAC unit. ECE series are offered as “Low Leak” and “Standard Leak” economizers.



Convertible Economizer MicroMetl

The MicroMetl Convertible Economizer (ECC) series are designed to work with vertical HVAC units, but can be converted to work in the horizontal application by either adapter panels provided with the economizer or a conversion kit that is purchased separately. For the horizontal conversion, a panel is provided to block the vertical return opening in the HVAC unit and the relief damper provided with the economizer is to be installed on the horizontal duct. ECC units come with “Low Leak” and “Standard Leak” options.



What Is An Economizer – AKA Mixing Box? – Economizer Class 101!

Economizers – Setting Minimum Position

HVAC – What Is An Adjustable Pitch Curb?

HVAC What Is An Adjustable Pitch Curb At MicroMetl

Abbie-Stancato-At-MicroMetl-Corporation-HeadshotHave you ever notice a rooftop which was not flat, but angled? Of course, we all have. Now imagine you must install a HVAC Rooftop Unit (RTU) on to the roof.

Perhaps you’re thinking, so what if the RTU is angled on the roof. Valid statement. Valid, but problematic… for starters HVAC rooftop units are designed to externally drain internal condensation, depending upon the angle, this could cause the condensation to collect and leak into the building, or cause rust issues by collecting on internal components.

The primary factor is weight distribution. A Roof Curb is designed for the weight of a RTU to be distributed directly downward. If you set a flat curb on an angled roof you are redistributing the weight disproportionately throughout the roof curb, and altering the RTU’s center of gravity. This could cause the roof curb to physically fail, and the RTU to fall off the rooftop; especially in storm and wind conditions which would pose little to no danger to a well seated, flat lying curb.

A Fixed Pitch Curb

Often when choosing a pitched curb, a specific fixed angle “Welded Pitch Curb” must be custom ordered. The pitch angle of the roof must be measured, and the exact placement and orientation of your RTU’s supply & return must be considered.


The Adjustable Pitch Curb is designed to pitch in any direction, and ships knockdown. It is less expensive than a fixed welded pitch curb, and offers job-site flexibility. All MicroMetl Adjustable Pitch Curbs are designed to pitch up to 1 in 12 inches in any direction. Adjustable Pitch Curb In Motion At MicroMetlMeaning they will set level on a roof which the roof pitch increases, or decreases 1 inch in height, for every 12 inches of roof extension or run.

The Adjustable Pitch Curb allows an installer to inventory less curbs, allows job site flexibility, and reduces wait time from manufacturing, while offering peace of mind knowing the incorrect “Welded Pitch Curb.” won’t be mistakenly ordered.

Adjustable Height – The Added Bonus

Most manufacturers construct a standard height 14 inch tall curb. Other standards (speaking specifically of MicroMetl), often consist of an 8, 11, 14, and 24 inch fixed height curb. Adjustable Height Curb In Motion At MicroMetlTherefore, if you desire a height outside of the standard, you will experience a slight premium for breaking the standard. The Adjustable Pitch Curb can save you the additional cost by acting as an Adjustable Height Curb.

Therefore, the same curb you could inventory for a pitched roof can save you money by allowing height requirement flexibility. Because the curbs are designed for a maximum of 1 in 12 inch pitch, the height adjustment will vary from curb to curb. Please feel free to contact the MicroMetl Customer Service Department to verify height requirements, or post your questions on our Open Forum!

Try MicroMetl’s Q&A Forum!

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Asked 1 year ago By Rick Furance
Category: Curbs
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Asked 1 year ago By Anonymous User
Category: General Questions
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Asked 1 year ago By Anonymous User
Category: General Questions
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Asked 1 year ago By Mike
Category: Curbs

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