Laars Pennant PNCP, Installation And Operation Instructions Manual

LAARS Heating Systems

Page 20

natural gas, 9.2% CO

2

 on LP). Check the CO

2

 of

the appliance and adjust if necessary.

3.

Ignitor failure: If the boiler goes through a
normal start cycle but combustion does not
occur, and the gas pressure is at least 5" w.c.,
ignitor failure may be the cause. Check the
ignitor by unplugging it, allowing it to cool to
room temperature, and measuring the ignitor
resistance. It should be 50-80 ohms. If the
resistance is not 50-80 ohms, replace the ignitor.
If the resistance is correct, reset the boiler and
check for 120 VAC at the ignitor plug during the
start cycle. If there is no voltage, replace the
faulty ignitor wire harness or the ignition control.

8.2 Delayed Ignition - Possible Causes

A defective burner can cause a delayed ignition.

If the gas supply pressure is proper and the gas valves
are functioning properly, then burners should be
inspected. There should be no distortion or
perforations in the burners outside of the active burner
port area. Replace if indicated.

8.3 Short Cycling

Because of the large mass of pool systems, short

cycling should not exist. If it does, it will be caused by
insufficient flow in the pool loop. Check that there is
no blockage in the pool loop such as a plugged or
partially plugged pool filter.

8.4 High Gas Consumption

Appliances operating with an improper air/fuel

ratio are very inefficient and consequently, have very
high gas consumption. Because efficiency is high
when the CO

2

 is high (or O

2

 is low), appliances

operating with low CO

2

 or high O

2

 (especially LP

appliances) consume more gas. Adjust the CO

2

 or O

2

for optimum efficiency. If no combustion analyzing
equipment (CO

2

 or O

2

) is available then a proper

adjustment of the air/fuel ratio (CO

2

 or O

2

) cannot be

accomplished. However, by briefly sniffing the flue
gases it is possible to determine if the CO

2

 or O

2

 is

within the proper range. No significant flue gas odor
should be detected when combustion is proper. A
strong piercing smell indicates poor combustion and
generally a lean mixture - low CO

2

 or high O

2 

. The

CO

2

 should be 8% (natural gas, 9.2% LP) at high fire.

To check the CO2, first verify that the supply gas
pressure is within 5" to 13" w.c. (1.2 to 3.2 kPa) With
the Pennant running with both stages firing, set the air
box pressure to 1.5" w.c. (0.37 kPa) (as a starting
point), by adjusting the air shutter(s) at the bottom of
the fan(s). Check the CO2, and adjust the air shutters
if further adjustment to the CO2 is needed. Models
1250, 1500, 1750 and 2000 have two blowers and two
air chambers (boxes). The pressure of each air box
must be equal when the final adjustment is made.

exchanger and metal sections by lifting up. On
the larger appliances, a center heat exchanger
support must be unbolted before it can be
removed.

7.

Remove the heat exchanger from the unit.
NOTE: The heat exchangers are heavy and will
require two people to remove to avoid personal
injury.

8.

Clean the heat exchanger: A light accumulation
of soot or corrosion on the outside of the heat
exchanger can be easily removed. Use a wire
brush to remove loose soot and scale from the
heat exchanger. Do not use water or compressed
air for cleaning.

9.

NOTE: While the heat exchanger is out of the
unit, inspect the firewall refractory insulation.
Replace if necessary.

10.

Inspect the inside of the copper tubes for scale
buildup. Scale can build up on the inner surface
of the heat exchanger tubes, which can restrict
water flow. If the tubes show signs of scaling,
clean the internal surface. Laars offers a tube
cleaning kit part number R0010000.

11.

Reassemble in the reverse order, and check
appliance operation after start-up.

NOTE: The Warranty does not cover damage
caused by lack of required maintenance, lack of
water flow, or improper operating practices.

SECTION 8.
Trouble Shooting

8.1 Resolving Lockouts

There are many causes of lockouts. The three

most common causes are: (1) inadequate gas supply,
(2) poor combustion, (3) ignitor failure.
1.

Inadequate gas supply: Before proceeding,
ensure that the gas supply has not been shutoff or
the LP tank (LP boilers) is not empty. Then,
restart the boiler and observe the operational
cycle. After a 15-second fan pre-purge, the
ignitor will heat up for 20 seconds, and then the
unit will light. If it does not, check the gas
supply pressure to the appliance, after resetting
the appliance and attempting another start-up.
The gas pressure to the appliance must be above
5" W.C. (1.2kPa) throughout the entire start-up
cycle. If it is not, correct the supply problem
(check gas valves or supply piping). If the supply
pressure is adequate, consult the factory for
assistance.

2.

Poor Combustion: Poor combustion should be
suspected if there is a strong flue gas odor. The
odor may result from an improper gas/air ratio
(high or low O

2

 or CO

2

). Pennant appliances

operate best with 45% excess air (8% CO

2

 on