LAARS HP-M2 Series - Installation, Operation and Maintenance Instructions - Manual (Page 21)

H Series Page 21
Keep boiler jacket louvers clear for proper
cooling of internal components.
Do not obstruct boiler room ventilation screens
or grills.
10B. Service Maintenance
Cleaning Heat Exchanger to be done by qualified
service person.
1.
Turn off electric and gas supplies and remove the
jacket.
2. Remove the vent assembly and top cover.
3. Remove the top half of the combustion chamber
by removing the three screws and nuts that clamp
the top half to the bottom half, the clamp on the
induction tube and the 1/8" diameter balance
lines.
4. Remove the top insulator cap by spreading the
retainer.
5. Remove the igniter - to avoid damage during
cleaning.
6. Clean the finned tubing with a wire brush and
vacuum all loose material from the combustion
chamber. Wipe flameholder (burner) with a clean
dry rag.
7. Replace all parts in the reverse order in which
they were removed.
8. Restart the unit as indicated by the operating
instructions plate.
SECTION 11.
Burner Input and Boiler
Component Descriptions
11A. Adjusting Burner/Input
The H Series burner system is a pre-mixed,
forced combustion system. Outside air is drawn
through the air orifice (located in the air induction
system) and mixed with the gas drawn in downstream
of the air orifice. The gas is metered through an orifice
located in the gas orifice union. All the air required for
complete combustion comes into the system in this
manner.
Adjusting the input is limited to changing the gas
orifice to achieve the proper input. The air orifice
cannot be altered and the gas valve pressure setting
cannot be changed.
Before changing the gas orifice to correct input,
service representatives should make the following
checks:
1.
The pressure on the inlet side of the gas valve is
between 4" and 13" water column.
2. The pressure on the outlet side (manifold) of the
gas valve and "T" above air orifice is between
negative .05" and negative .35" water column
with the unit operating.
To increase the input, install larger diameter gas
orifice. Each size will change the input approximately
5 C. F. H. Once the correct input has been achieved,
the burner should be checked with an oxygen (O2) or
carbon dioxide (CO2) gas analyzer.
The unit should be in operation 5 minutes before
adjusting input or taking CO2 or O2 readings. This
time will allow for pre-heating of the intake air.
Insert the probe of the O2 or CO2 tester at least
6" into the vent through the vent terminal. If CO2 is
being measured, the readings should be between 8.0
and 8.5 for natural gas and 9.0 and 9.8% for propane.
If O2 is being measured, the readings should be
between 7 and 6.
11A-1. Measuring CO
2
*
When operating on natural gas, readings below
8.0 generally indicate a lean mixture (not enough gas).
Readings above 9.25 generally indicate a rich mixture
(too much gas). Inputs should be increased or
decreased to correct lean or rich mixtures.
NOTE: If the mixture is very rich (not enough
air for complete combustion), it is possible to get low
readings on a CO2 analyzer. This situation does not
occur often but it can be detected if reading continues
to go lower as the input is increased. If this condition
is suspected, a CO test should be taken at the vent
outlet. Inputs must be reduced to correct high CO
reading and to bring CO2 readings to proper levels.
* The following numbers apply to natural gas
only. The range of operation for LP is 9.0 to 9.8.
11A-2. Measuring 0
2
Readings above 7% indicate a lean mixture (not
enough gas). Readings below 4½% indicate a rich
mixture. Input should be increased to correct lean
mixtures or decreased to correct rich mixtures.
11B. Cleaning Combustion Chamber Coil
1. Turn off electric and gas supplies and remove the
jacket.
2. Remove the vent assembly and top cover.
3. Remove the top half of the combustion chamber
by removing the 3 screws and nuts that clamp the
top half to the bottom half, the clamp on the air
orifice hose and the two clear plastic lines
connected to the "T" on the air induction elbow.
4. Remove the top insulator cap by spreading the
retainer.
5. Remove the igniter.
OUT OF
PRODUCTION