Rapid Engineering CTHN-40, Installation & Operation Manual

Page: 60 / 100

CTHN-S
ERIES
I
NSTALLATION
, O
PERATION AND
S
ERVICE
M
ANUAL
54 of 91
SECTION 12: VENTING - UNITARY HEATER
All general venting req u irements apply.
See Page 53, Section 11 .
Exha u st end of fan w ill accept a 4'' (10 cm) vent pipe.
To prevent leakage of condensation, seal all the vent
joints
u sing a high temperat u re silicone sealant.
The heater may be individ u ally vented or common
vented. When venting horizontally, a maxim u m of t w o
heaters can be commonly vented. See Page 56,
Section 12.9 . When venting vertically, a maxim u m of
fo u r heaters can be commonly vented. See Page 57,
Section 12.10 .
The CTHN u nitary heater may also be installed
u nvented in certain circ u mstances according to
b u ilding ventilation codes. Refer to the codes on
Page 53, Section 11.1 and Page 54, Section 12.1 for
f u rther information. Unvented operation also req u ires
compliance w ith the clearances to comb u stibles
given on Page 8, Figure 12 .
12.1 Unvented Operation
S u fficient ventilation m u st be provided 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 comb u stion air is not
recommended w ith u nvented heaters.
If exha u st fans are u sed to s u pply ventilation air, an
interlock s w itch m u st be u sed to prevent the heater
from coming on w hen the fans are off. This may be
done u sing a press u re s w itch.
12.2 Unvented Operation Termination
For u nvented operation, t u rndo w n type vent terminal
w ith a screen m u st be installed at the exha u st end of
the fan. Vent terminal design shall not incorporate
backdraft flap.
FIGURE 27: Fan Termination
12.3 Horizontal Venting
In noncomb u stible w alls only, vent terminal
(P/N 02537801-1P) may be u sed.
For 4'' (10 cm) vents in either comb u stible or
noncomb u stible w alls, u se Tjernl u nd VH1-4 (P/N
90502100) or eq u ivalent, ins u lated vent terminal.
Follo w the man u fact u rer's instr u ctions for proper
installation.
For 6'' (15 cm) common vents in either comb
u stible
or noncomb u stible w alls, u se Tjernl u nd VH1-6 (P/N
90502101) or eq u ivalent, ins u lated vent terminal.
Follo w the man u fact u rer's instr u ctions for proper
installation.
12.4 Vertical Venting
For 4'' (10 cm), an approved vent cap
(P/N 90502300) m
u st be u sed.
For 6'' (15 cm) common vent, an approved vent cap
(P/N 90502302) m
u st be u sed.
For common vertical venting of more than t w o
heaters, See Page 57, Section 12.10 .
12.5 Length Re q uirements
The maxim u m vent 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 vent length, pl
u s o u tside air d u ct length and
any extensions to minim u m heat exchanger lengths,
cannot exceed 65' (19.8 m).
Vent length sho
u ld be limited to less than 20' (6 m).
If u sing extended heater lengths or vent lengths
greater than 20' (6 m), condensation w ill form in the
vent 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 beyond minim u m lengths is
considered as vent length for length determination.
S
u btract 15' (4.6 m) of maxim u m allo w ed vent or d u ct
length per vent elbo w if more than t w o are u sed.