060302a Flashcards
Definition of a BTU?
The quantity of heat required to raise the temperature of one pound of fresh water one degree Fahrenheit
What is infiltration?
Airflow inwards through a crack/space in windows and doors
K Value
THERMAL CONDUCTIVITY
Number of heat units (Btu) that will pass through 1 square foot of material 1 inch thick in 1 hour for each degree F difference in temperature between the two surfaces of material
Single material btu/hr
R Value
THERMAL RESISTANCE
The value of a given materials ability to resist heat transfer or flow; the higher R value the greater insulating value or resistance to heat transfer
R Value hr/btu
Opposite of K value
How do your turn R value to K value?
1 divided by R value
1 / (20hr/btu) = 0.05btu/hour (K value)
U Factor
The quantity of heat in btu/hr (Btuh) flowing through 1 square foot of walls, ceiling, floor and roof or glass area for every degree temperature difference between the air inside and the air outside
Multiple layers
BTU/hr
Maximum in-floor run lengths for
3/8”
1/2”
3/4”
3/8” - 250’
1/2” - 300’
3/4” - 500’
How do you calculate min and max lengths of in-floor runs?
Min length
= longest length x 0.9
Max length
= shortest length x 1.1
With in-floor heat what is heating the space? The water or the floor?
The floor
Floor temperature shall not exceed…
77°F in areas people stand long periods
88°F in a dwelling or commercial space
91°F in bathrooms, indoor swimming pools and foyers
95°F in radiant panel perimeter areas
If both rooms are on the same zone the mean water temp setting would be based on the room with the ______ water temp.
highest
Low temp is considered anything under ____°F
140
How do you convert an R value into a U value?
U=1/R
R=1/U
