Line D Mech Venting Systems Flashcards
What can be the results of an improperly selected, sized and/or installed venting system?
Efficiency loss, Appliance damage, Increased appliance maintenance, damage to breeching & stack, Production downtime, Increased operating costs.
Define forced draft:
A mechanical draft produced by a device upstream from the combustion zone of an appliance
What is the draft source for a natural draft appliance? Explain how this draft source moves the products of combustion through the appliance and the venting.
Gravity is the source. It moves the products of combustion through the appliance and venting because the hot flue gases are lighter and naturally rise (buoyancy).
Define induced draft:
A mechanical draft produced by a device downstream from the combustion zone of an appliance
Describe the three general variations of Burner inlet blowers and the different pressures associated with each.
a. Blowers which operate with enough pressure to overcome the burner alone. The combustion chamber, appliance outlet and venting will all be under negative pressure
b. Blowers which operate with enough pressure to overcome the burner and combustion chamber. The combustion chamber will be under positive pressure, appliance outlet will be neutral or negative and the appliance venting will be under negative pressure
c. Blower which operates with enough pressure to overcome the burner, combustion chamber and part or all of the venting. All parts of the system past the burner are under positive pressure.
What is the pressure upstream of the blower when it is located on the outlet of the appliance?
Negative
What is the pressure downstream of the inducer blower located on the outlet of the appliance?
It will be positive immediately downstream but could be either negative, neutral or positive on the downstream side depending on the blower’s power and the venting system
In a venting or chimney system with mechanical draft what two types of draft can be present and what type of pressure is associated with each?
Forced draft – static pressure in the venting is positive
Induced draft – static pressure is the venting is negative
When a venting system was originally installed as a gravity system where is the best location for the blower to be located? Why?
Forced draft – static pressure in the venting is positive
Induced draft – static pressure is the venting is negative
What must be done when a power venter is used in place of a natural draft venting system.
Gas flow to the main burner must be prevented in the event of power venter failure
When must design registration take place when you are designing or modifying complex, technical, and regulated equipment in BC?
Before the construction and installation of the equipment
When are parallel blade damper used?
For open/closed operation
When are opposed blade dampers used?
For modulating operation
What must be done when an automatic flue damper is installed on an appliance with a continuous pilot?
Must have a fixed minimum opening of 20% of the flue area and be interlocked with the burner control system so the that damper is proved fully open before ignition of main burner and The fuel supply to the appliance will be shut off in the event of failure except where the damper will fail fully open.
What are three common ways to prove draft in an appliance or venting system?
A pressure switch, An integrated proven draft switch, A pressure transducer
