• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

12 Cards in this Set

  • Front
  • Back

What is a buildings heating load? When does maximum heating load occur?

It is a buildings maximum heat loss during the heating period.

When the outside temp is lowest.

What's is the general design tem p for HVAC? What is HVAC basically a practical application of?

Anywhere between 21.1 to 22.2


What is total resistance R? What are eqs for R?

It is the total resistance to heat flow through the entire thickness of material.

R = 1 / C and k = R / L

k is the conductivity, resistance per unit thickness of the material

L is length or thickness.

What is eq for heat transfer through walls, Windows, doors, and ceilings? What is U and how is it found?

Qdot = U*A*(Ti-To)

Overall heat transfer coefficient. U = 1/sum(R) = 1 / [1/hi + sum(L/k) + sum(1/C) + 1/ho].

What is ventilation? What is sensible heat? What is latent heat? What are eqs for both? Which is usually more significant?

Ventilation is providing air and humidification to an occupied space.

Sensible heat is pure thermal energy that increases airs dry-bulb temp

Latent heat is moisture that increases airs humidity ratio.

Qs = mdot*cp*(Tid-Tin)=Vdot*density*cp*(Tid-Tin). Where Tin is dry bulb temp of air entering room

Ql = mdotwater*hfg = mdotair*∆w*hfg= Vdot*density*∆w*hfg

Sensible loads usually more significant and ventilation can be determined solely on that. However latent becomes more considerable if large moisture sources are present

What is the sensible heat ratio? What is the latent factor?

SHR = Qdotsensible / (Qdotsensible +Qdotlatent)

LF = 1 / SHR

What is the bypass factor? What is the lever rule i can use to find it? how do i find it graphically?

It is the ratio of the bypassed air to the total AMT of air.

BF = (Tmix - Tcond) / (Troom - Tcond)

Plot the two points on the psychrometric graph. The indoor design conditions (dry bulb and wet bulb temps) and the sat temp (ususlly of air leaving a/c) or dew-point temp same thing. Then plot a line between the 2 pts. Then the BF will be the distance of the conditions of air entering the space to the Sat temp pt over the total length of the line plotted.

How do you use sensible heating ratio on psychrometrics chart?

Use them protractor at the top to find the slope and then plot the line.

What is saturation %?

Another way to say relative humidity

When a problem mentions air passing through a reheater and being raised sensibly what does that mean?

If temp is being raised sensibly it is a represented by a horizontal line on the psychrometrics chart

If I know the dry-bulb and wetbulb temps what can I find for air at those conditions on the psychrometric chart?

v specific volume and w humidity ratio.

If I am given wet bulb and dry bulb conditions for air for in and them have the relative humidity % of exit air what do I on the psychrometric chart to find exit conditions? If it's adiabatic (no heat applied)

Basically from the pt that corresponds to given db and wb temps from a line up and to the left following constant enthalpy until it intersects with relative humidity line.