Exam (elaborations)
HVAC Midterm Chapters 1-4 EXAM with complete solution 2024_2025
- Course
- Institution
HVAC Midterm Chapters 1-4 EXAM with complete solution 2024_2025
[Show more]
Content preview
HVAC Midterm Chapters 1-4 EXAM withcomplete solution 2024/2025
cooling process - ANSWER-removes heat from from air, which causes the temp
of the air to drop
ventilation - ANSWER-supplies or removes air from space (required to replenish
the oxygen supply) (dilutes odor) (provide makeup air for rooms with exhaust
systems; maintains acceptable air balance
Factors that influence human comfort - ANSWER-Temperature, humidity, Air
quality, and Air movement
heating, cooling, filtration, ventilation & humidification are collectively called -
ANSWER-Air Conditioning
2 common complaints - ANSWER-temp to hot or cold & humidity is either to high
or too low
Fixed louvres - ANSWER-redirect the airflow; causing rain/snow to fall out of air
suspension
Dampers - ANSWER-control the airflow
finned heating coils - ANSWER-some may be use steam to heat air, steam goes
through coil & heats air traveling around, steam condenses inside coil & returns
to boiler
,finned cooling coils - ANSWER-chilled water to cool air, water circulates through
coil & removes heat from air travelling around coil, warmed water leaves coil &
returns to chiller
An increased air flow increases the heat loss of the body by - ANSWER-
conduction, convection & evaporation which helps body to remain comfortable
when the room temp is higher than normal.
humidifiers - ANSWER-add water to air, pump water from water bath & inject it
into airflow using spray nozzles
Air diffusers - ANSWER-direct the flow of air into the space without creating a
draft
fans - ANSWER-create airflow/air movement
Return air - ANSWER-% of exhaust air is recirculated to increase building
efficacies & lowers the operating costs. This air must be retreated
Outside air - ANSWER-aka make-up air, regulated by building codes; used to help
maintain human health conditions
mixed air - ANSWER-mixture of return air & make-up air (needs to be treated)
supply air - ANSWER-air treated by HVAC system that's supplied to the building
Human health is the key criteria when deigning an - ANSWER-HVAC system
Effective temperature (ET) - ANSWER-(temperature, humidity & air movement)
measure of comfort that which involves the combined effects of dry-bulb temp,
relative humidity & air movement (not an actual temp even though its expressed
in C & F) (cannot be measured with a thermometer)
An airflow of 4-8 m/min is considered - ANSWER-relatively still
air draft of 19.8 m/min, most people would consider it to be a - ANSWER-draft
crowded spaces should be kept at - ANSWER-lower temperatures
rooms on the north side should be kept - ANSWER-warmer during winter
, moisture added to increase the RH minimizes the effects of - ANSWER-static
electricity
in colder climates, dehumidification may be required in humid areas to prevent: -
ANSWER-structural damage during winter due to frost formation in exterior walls
Air movement/circulation is required in each space to dissipate _______________
from occupants & prevents build up of __________ which may develop in
stagnant areas. - ANSWER-body heat, odors
Air filters must remove contaminates (impurities) such as - ANSWER-dust, dirt,
smoke, pollen & lint
temperature kept between _____________ & best for everyone is ________ -
ANSWER-18-22 degrees & 20
Humidity kept between ___________ and best for everyone is ________ -
ANSWER-30-70% and 50%
Humidity in winter is best at _______ - ANSWER-30%
Humidity in summer is best at ______ - ANSWER-70%
relationship of temp & humidity is called - ANSWER-psychometrics
radiant heat - ANSWER-rooms on sunny side kept cooler
higher temps if occupants in building for (prevents discomfort) - ANSWER-short
amount of time
Unitary systems - ANSWER-each individual room/zone has a self contained AC
unit; maintains the desired environmental conditions
Central systems - ANSWER-air handling unit in central mechanical room, ducts
distributes (filter, humidify/dehumid, heat, cool; can have thermostat in each
room, provide individual room temp
Combined systems - ANSWER-air handling unit in central room, ducts distribute
(usually only has ventilation, preheating & cooling) supplementary equip located
in each zone to provide heating + additional cooling. Complex, costly but superior
zone temperature control
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller tuition. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
82871 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now