Therma Grow™ Greenhouse Heaters
Owner’s Manual • Therma Grow™
27
Th
re
e
Ti
m
es
Ignition failure Hea
ter
does n
ot light
or
st
ay lit.
Is
LP tank
full and p
roperly
sized and are all gas
supply
val
ves
to
hea
ter open?
Fill tank or resize if necessa
ry
. Open all
gas supply
val
ve
s
Ye
s
No
Is p
roper gas
pressure supplied
to
h
ea
ter?
Ye
s
Are
24
volts sent
from
terminal
GV of
cont
roller
to high
limit switch a
fte
r
igni
ter
w
arm up and
fan m
ot
or resta
rts?
H
av
e
the bu
rner
or
ifice, bu
rner
cast
ing and mani
fol
d
been chec
ked
fo
r
bloc
kage?
Ye
s
Ye
s
Is p
ro
pe
r
bur
ner
mani
fol
d
pre
ssu
re r
ea
d at
ou
tlet of ga
s
val
ve
?
Does igni
te
r
gl
ow?
Is flame
sensor clean?
Is igni
te
r
pr
operly
connec
ted?
Ar
e
11
5
vol
ts
su
pplied f
ro
m
ter
minal HSI on
ignition cont
ro
l
mod
ule
to
igni
te
r?
Ye
s
Ye
s
Are high limit switch contacts
closed?
Ye
s
Ye
s
Ye
s
(A
)
If l
ow or high pressure
is read, adjust outlet pressure.
(B
)
If gas pressure is n
ot
read, replace the gas cont
rol
val
ve
.
De
fecti
ve igni
te
r.
Pe
rform continuity
check and replace igni
ter If necessa
ry
.
Clean flame sensor with eme
ry cl
oth or
st
ee
l w
oo
l.
Connect igni
te
r
to igni
ter p
ow
er
supply wiring.
Check wiring bet
w
een module and
co
m
ponent.
Repair or replace as
necessa
ry or replace ignition cont
rol .
Pr
ovide p
ro
pe
r
pressure
to
h
ea
te
r
and check with a
gauge.
Check
for
voltage
to
switch. Check wiring and repair if de
fecti
ve
If wiring is good and voltage is n
ot present,
replace ignition
cont
rol.
No
Re
m
ov
e o
rif
ice and
burner casting. Bl
ow
out with co
m
pressed
air or clean with a
so
ft brush.
No
No
No
No
No
No
No
No
Has wiring been
chec
ke
d
bet
w
een ignition
cont
rol and
sensor?
Ye
s
Check wiring bet
w
ee
n
cont
rol and
co
m
ponent.
Repair
or replace .
No
Is
flame sensor
insula
to
r
crac
ked?
Ye
s
Replace senso
r.
No
Is
flame sensor
pr
operly
positioned?
Ye
s
Position flame sensor so 1/2 - 3/4 in. of tip is in burner flame.
No
Is hea
te
r
pr
operly
gr
ounded?
Contact electrician.
Sys
tem must be
gr
ounded
fo
r
pr
oper operation.
No
Are
24
volts
supplied f
rom the
high limit switch
to
the gas cont
ro
l
val
ve
?
Ye
s
Check
for
voltage
to
val
ve. Check wiring
and repair if de
fecti
ve
.
If wiring is good and voltage is n
ot present,
replace limit switch.
No
Pe
rform continuity chec
k.
If switch is open reset the switch. Check the
foll
owing:
-- Con
firm correct fuel
for hea
te
r..
-- P
roper
voltage
to
m
ot
or
-- Dust and di
rt build-up
-- Plugged
fan assembly
--
Fan n
ot tigh
tened
to
m
ot
or
--
Obstructions in air inlets or discharge outlet of hea
te
r.
Ye
s