Line D DFMAs

Question 1

A direct fired make-up air unit is designed for temperatures ranging from -5⁰F to 85⁰F. At what outdoor temperature (within design parameters) will the velocity across the burners be the greatest?

Answer 1

85⁰F

Question 2

A direct fired makeup air heater has the same function as an RTU.
TRUE / FALSE

Answer 2

FALSE

Question 3

What is the main benefit of a DFMAH?

Answer 3

No efficiency lost to a heat exchange

Question 4

Referring to the B149.1 under what conditions can a DFMAH be used?

Answer 4

A DFMAH shall not be installed unless it is necessary to exhaust air and replace it with preheated air

Question 5

What must be proved before the DFMAH can start?

Answer 5

Any inlet or discharge air louvres must be proved open through an interlock with the control the exhaust system is operating

Question 6

What is the purpose of makeup air?

Answer 6

To replace the air exhausted by large exhaust appliances which, when properly designed, installed and maintained ensure a neutral pressure in the building

Question 7

When a DFMAH is used in a kitchen it must be interlocked with the kitchen exhaust fan so that neither fan can operate without the other operating?
TRUE / FALSE

Answer 7

TRUE

Question 8

List three things that could affect the external static pressure placed on a DFMAH.

Answer 8

Filters, Grilles, Ductwork

Question 9

When the DFMAH is in operation the burner is always firing?
TRUE / FALSE

Answer 9

FALSE

Question 10

What are the two modes of operation for a spray booth DFMAH?

Answer 10

Spray Mode, Bake Mode

Question 11

In a DFMAH what is adjusted to control air velocity?

Answer 11

Profile plates

Question 12

Other than make up air for a kitchen or spray booth list three other applications for DFMAH.

Answer 12

Shaft pressurization (stairwell or elevator), storage garage, mine shaft