Owner`s manual

32925-3-0115Page 18

Thespaceintheaboveexampleisaconnedspacebecausethe
actual BTU/Hr used is more than the maximum BTU/HR the space
can support. You must provide additional fresh air. Your options
are as follows:
A. Reworkworksheet,addingthespaceofanadjoiningroom.If
theextraspaceprovidesanunconnedspace,removedoor
toadjoiningroomoraddventilationgrillsbetweenrooms.See

B. Vent room directly to the outdoors. See 
Outdoors.
C. InstallalowerBTU/Hrheater,iflowerBTU/Hrsizemakesroom
unconned.
If the actual BTU/Hr used is less than the maximum BTU/Hr the
spacecansupport,thespaceisanunconnedspace.Youwillneed
no additional fresh air ventilation.
WARNING

space.
Ventilation Air

Thisfreshairwouldcomefromanadjoiningunconnedspace.When
ventilatingtoanadjoiningunconnedspace,youmustprovidetwo
permanentopenings:onewithin12"oftheceilingandonewithin
12"oftheooronthewallconnectingthetwospaces(see options
1 and 2, Figure 23). You can also remove door into adjoining room
(see option 3, Figure 23). Each ventilation grill or opening shall
haveaminimumfreeareaofonesquareinchper1,000BTUHof
thetotalinputratingofthegasequipmentintheconnedspace.
Figure 23
WARNING
       

.

Provideextrafreshairbyusingventilationgrillsorducts.Youmust
providetwopermanentopenings:onewithin12"oftheceilingand
onewith12"oftheoor.Connecttheseitemsdirectlytotheoutdoors
or spaces open to the outdoors. These spaces include attics and
crawl spaces. In most cases for direct communication with the
outdoors or direct communication through a vertical duct a free
areaopeningofonesquareinchper4,000BTU/Hrofheaterinput
rating for each grill. If a horizontal duct is used, a grill free area or
ductopeningshallhaveafreeareaopeningofonesquareinchper
2,000 BTU/Hr for each grill. Follow the National Fuel Code ANSI
Z223.1/NFPA54, Air for Combustion and Ventilation for required
size of ventilation grills or ducts.
IMPORTANT: Do not provide openings for inlet or outlet air into attic
if attic has a thermostat-controlled power vent. Heated air entering
the attic will activate the power vent.
Figure 24
A1 A2
B1
B2
A1 x B1 = C1
A2 x B2 = C2
C1+C2=Sq.In.Required
Fora30,000BTUHeater,1sqinper1,000BTU
equals30sq.in.ofopening.
(A1) 5in
2
x (B1) 3in
2
= (C1) 15in
2
(A2) 5in
2
x (B2) 3in
2
= (C2) 15in
2
(C1) 15in
2
+ (C2) 15in
2
= 30in
2
Figure 25