Lennox G21Q Series Unit Information

GAS METER
TEST
DIALS
CUBIC
FEET
FIGURE 69
Page 50
K − Condensate pH Range
Unit condensate is mildly acidic and can be measured with
pH indicators. The pH scale as shown in figure 68 is a mea
surement of acidity or alkalinity.
Concentration of acidity of all these fluids including con
densate is very low and harmless.
The following scale shows relative pH of some common liquids
as compared with G21/GSR21 condensate.
FIGURE 68
pH RANGE
0
1
2− Vinegar
3− Wine
4− Orange Juice
5− Tomato Juice
6
7− tap water
8
9
10
11
12
13
14
Increasing Acidity
Increasing Alkalinity
G21/GSR21
Condensate
Range
L − Acceptable Operating Input
Field adjustments to the unit are not normally needed due to
specifically sized components for each input rating.
Unit may run up to + 3 to 4 percent of rated input (listed on
unit nameplate) due to installation variables such as tem
perature rise, external static pressure and return air tem
perature combined with allowable tolerances of compo
nents within unit. This is an acceptable operating range.
Operation of the G21/GSR21 above or below this accept
able operating range may cause continuity, startup and
lockout problems (erratic operation). Overfiring the unit
can shorten the life of the heat exchanger assembly. Over
firing can be checked by measuring unit’s input.
IMPORTANT
Overfiring the unit can shorten the life of the heat
exchanger assembly
For new units, approximate input measurements may be ob
tained after allowing unit to run continuously for 15 minutes. If
accurate input measurements are required, the following pro
cedure may be used. Accurate input measurements requires
time for the unit to run in."
Run in time allows flapper valves to seat and combustion to
clean the protective layer of oil residue that may be present
from inside surfaces of the heat exchanger assembly. This
process stabilizes combustion rate and may take one to
two hours of continuous operation. Since it is impractical to
operate an installed unit for one to two hours continuously,
the unit should be allowed to operate normally, (cycle on
demand) for a period to accumulate several total hours of
run time to obtain an accurate measurement of input. Over
night operation should provide enough total run time to ob
tain an accurate measurement of input. Just prior to any in
put check, run unit continuously for 15 minutes.
M − Checking Gas InputDetermine Gas
Flow at Meter
1 − Turn off all other gas appliances, including pilot lights
or appliances if used.
2 − For single stage V" units jumper HB to W2.
3 − Set thermostat to highest setting and allow unit to
run continuously for 15 minutes. A 15 minute run
time is needed to allow unit operating rate to stabi
lize.
4 − At the gas sup
ply meter and
using either
one, two,
three or five
foot dial on the
meter, time
one full revolu
tion (in sec
onds) with a watch. See figure 69.
5 − Find the number of seconds for one revolution on the
Gas Rate chart, see table 16 . Read the cubic feet for
matching one, two, three or fivefoot dial size from
table 16 multiply this times Btuh per cubic foot content of
the gas. The result is total gas Btuh input.
6 − Check Btuh input figure against Btuh listed on unit
nameplate.

Lennox G21Q Series Specifications

General

Brand	Lennox
Model	G21Q Series
Category	Industrial Equipment
Language	English