Heat Loss

Question 1

why do we perform heat loss on a structure

Answer 1

to properly size the appliance, piping, duct work, and HDU’S (heat distribution units)

Question 2

can heat transfer be stopped

Answer 2

heat transfer can only be slowed never stopped

Question 3

how does heat move

Answer 3

heat moves from an area of higher concentration to an area of lower concentration by conduction convection or radiation

Question 4

what is a BTU

Answer 4

the amount of energy needed to raise one pound of water one degree fahrenheit

Question 5

what is transmission loss

Answer 5

heat loss through the envelope by means of conduction ex: windows doors etc

Question 6

two factors that effect transmission losses

Answer 6

wall construction and delta T

Question 7

explain infiltration

Answer 7

warm air leaves building cold air replaces it because the building psi is less than the outdoor psi

Question 8

why is infiltration bad

Answer 8

heat loss from building leads to lower efficiency

Question 9

five reasons infiltration is good :)

Answer 9

oxygen rich air
removes moisture
removes odors
removes chemicals from cleaners
removes outgassing

Question 10

when is mechanical ventilation needed in winter

Answer 10

when there is less than .5 ACH

Question 11

What is the R Value

Answer 11

number of hours it takes for 1 btu to pass through one square foot of material, with one degree delta T between the two sides

Question 12

What is the U Value

Answer 12

number of BTU’s that will pass thru 1 sq. ft of material in 1 hour with 1 degree delta T between the 2 sides

Question 13

why is solar gain not accounted for when computing heat loss?

Answer 13

our designed condition is for the winter (no sun)

Question 14

table 1 is used to find what

Answer 14

outdoor design temp (ODT)

Question 15

what does the 97.5 % column mean

Answer 15

it means that we are at or above that temp 97.5% of the time

Question 16

table 2 is used to find what

Answer 16

HTM’s

Question 17

what is the accepted IDT for calculating heat loss

Answer 17

70 degrees

Question 18

please list 9 ways heat is lost from a building

Answer 18

roof - ceilings
exposed walls
doors and windows
slab floors
below grade walls
partition
basements floors  
ceiling to attic
floor loss to crawl space
duct loss to unconditioned space

Question 19

4 ways heat is lost from a heating system

Answer 19

1. Ducts in unheated spaces
2. Vent air must be heated before entering space
3. Bathroom and kitchen exhaust fans
4. Outside air intake to feed combustion

Question 20

when measuring windows and doors we round to the nearest

Answer 20

tenth (.1 )of a foot then the nearest square foot

Question 21

wall length we round to

Answer 21

nearest foot

Question 22

wall heights we round to

Answer 22

nearest half foot

Question 23

gross exposed wall area round to

Answer 23

nearest sq foot

Question 24

wind speed u factor table 2

Answer 24

15mph

Question 25

TIM stands for

Answer 25

thermally improved metals obviously

Question 26

htm stands for

Answer 26

heat transfer multiplier

u factor x delta t

Question 27

how should a stair case be accounted for

Answer 27

when a staircase is next to an outside wall it should be included with the gross exposed wall area of the hall or room below it

Question 28

how should a small closet be accounted for

Answer 28

included with adjoining rooms duh

Question 29

how are large closets accounted for

Answer 29

their own room

Question 30

do we need to calculate for cfms in bathroom or kitchen fan

Answer 30

no because it runs intermittently

Question 31

if a wall extends a foot and a half below grade how do we calculate its tranmission loss and why

Answer 31

we calculate it as above grade because ground temp is almost the same as outdoor temperature

Question 32

where do we loose heat on a slab

Answer 32

on the edges of the slab (outside)

Question 33

maximum oversizing of fossil fuel or boiler appliance

Answer 33

when sizing a fossil fuel furnace or boiler we should oversize to 100% maximums the designs heating load requirement due to the increments of the product line capacity