Rapid Engineering BH-40, Installation, Operation & Service Manual

Page: 42 / 68

BH-S
ERIES
I
NSTALLATION
, O
PERATION AND
S
ERVICE
M
ANUAL
36 of 59
8 .2 Unvented Operation
S u fficient v entilation m u st b e pro v ided in the amo u nt
of 4 cfm per 1000 Bt u /h firing rate (United States); 3
cfm per 1000 Bt u /h firing rate (Canada).
Use of optional o u tside com bu stion air is not
recommended w ith u n v ented heaters.
If exha u st fans are u sed to s u pply v entilation air, an
interlock s w itch m u st b e u sed to pre v ent the heater
from coming on w hen the fans are off. This may b e
done u sing a press u re s w itch.
8 .3 Horizontal Ventin g
In noncom bu sti b le w alls only, v ent terminal
(P/N 02537801-1P) may b e u sed.
For 4" (10 cm) v ents in either com bu sti b le or
noncom bu sti b le w alls, u se Tjernl u nd VH1-4 (P/N
90502100) or eq u i v alent, ins u lated v ent terminal.
Follo w the man u fact u rer's instr u ctions for proper
installation.
For 6" (15 cm) common v ents in either com bu sti b le
or noncom bu sti b le w alls, u se Tjernl u nd VH1-6 (P/N
90502101) or eq u i v alent, ins u lated v ent terminal.
Follo w the man u fact u rer's instr u ctions for proper
installation.
8 .4 Vertical Ventin g
For 4'' (10 cm) common v ent, an appro v ed v ent cap
(P/N 90502300) m u st b e u sed.
For 6'' (15 cm) common v ent, an appro v ed v ent cap
(P/N 90502302) m u st b e u sed.
For common v ertical v enting of more than t w o
heaters, See Page 38, Section 8.10 .
A v ent shall not extend less than 2' (0.6m) a b o v e the
highest point w here it passes thro u gh a flat roof of a
bu ilding.
8 .5 Unvented Operation Tube Termination
T u rndo w n type v ent terminal w ith a screen m u st b e
installed at the exha u st end of the t ub e. Vent terminal
design shall not incorporate b ackdraft flap.
FIGURE 22: Tube Termination
8 .6 Len g th Re q uirements
The maxim u m v ent length allo w ed is 45' (13.7 m).
The maxim u m o u tside air s u pply d u ct length allo w ed
is 45' (13.7 m).
The total
v ent length, pl u s o u tside air d u ct length,
pl u s any extensions to minim u m heat exchanger
lengths, cannot exceed 65' (19.8 m).
Vent length sho u ld b e limited to less than 20' (6 m). If
u sing v ent lengths greater than 20' (6 m),
condensation w ill form in the v ent pipe. Ins u lation
and additional sealing meas u res (high temperat u re
silicone at all seams) are req u ired. Optional heat
exchanger b eyond minim u m lengths is considered as
v ent length for length determination.
S ub tract 15' (4.6 m) of maxim u m allo w ed v ent or d u ct
length per v ent el b o w if more than t w o are u sed.
8 .7 Horizontal Ventilation 4'' (10 cm) Pipe
4" (10 cm)
Single Wall Pipe
Vent Adapter
Vent Terminal
Combustible or
Non-Combustible Wall
Vent Adapter
18" (46 cm)
Min.
Vent Terminal
4" (10 cm) Single Wall Pipe
Non-Combustible Wall Only
SIDE VIEW
Description Part Number
Vent Terminal (Com b . Wall) 90502100
Vent Terminal 02537801-XX