LAARS EBP 175 MBTU/h - Installation, Operation and Maintenance Instructions - Manual (Page 36)

Page 36 LAARS Heating Systems
antifoamants, are appropriate for the ENDURANCE
boilers.
NOTE: The concentration of appropriate antifreeze
should always be kept as low as possible to minimize
its effect on heat transfer and efficiency.
The method for eliminating the boiling noise
is the same regardless of the cause. However, if
antifreeze in the system is suspected of being the
cause, the concentration (<35%) and type should be
investigated.
Moisture
Although it is not a primary cause of lockouts,
moisture in the combustion chamber may cause
lockouts by weakening the flame signal to the boiler
control. It should be suspected if the boiler temperature
does not rise above 160°F during long periods of
operation. This condition can be caused by the failure
of the anticondensing valve in Endurance boilers.
Moisture can also get into the combustion chamber
through an incorrectly pitched or incorrectly installed
flue pipe (pitched back toward the boiler without a
condensate trap). The flue assembly of Endurance
boilers installed as Direct Vent boilers should always
pitch down from the boiler.
11.4 Insufficient Hot Water
Possible cause:
a. No flow restrictor (supplied with unit - field
installed)
b. Water flow switch failure
c. Mixing valve setting or failure
d. Domestic hot water (DHW) heat exchanger
contamination
The most common cause for insufficient hot
water complaints results from failure to install a flow
restrictor. The absence of a flow restrictor allows
water to pass through the heat exchanger at a greater
rate than the boiler output is capable of heating to the
desired temperature.
Failure of the water flow switch to operate during
a hot water draw prevents boiler water from flowing
through the DHW heat exchanger and therefor the
DHW will not be heated.
To test the switch, place a temporary jumper
across the flow switch terminals. If the internal
pump operates and there is DHW generated then the
water flow switch is faulty and must be replaced.
Note: Switch orientation is critical for proper switch
operation, The identification plate on the switch must
face up and the arrow on the plate must point in the
direction of flow.
Failure of the mixing valve will allow cold
water to be mixed with the hot water from the DHW
heat exchanger during a DHW draw regardless of the
setting of the mixing valve or the temperature of the
water leaving the DHW heat exchanger. The failure
can be detected by observing the temperature of the
three pipes connected to the mixing valve. If the
“mix” temperature is luke warm or cool and the “hot”
temperature is hot and the “cold” temperature is cold
then the mixing valve is either faulty or incorrectly
adjusted and must be replaced or adjusted.
DHW heat exchanger scaling may occur in
some areas of the country where there are high
concentrations of minerals in the water. These minerals
may cause fouling of the DHW heat exchanger over
an extended period of time (lime build up). Other
minerals, which react more quickly in well systems
(mostly magnesium), cause slime on the inside of the
heat exchanger and prevent adequate heat transfer.
These minerals must be filtered out by a special
incoming water filter or by the addition of an inhibitor
to protect the coil and provide acceptable water
quality. Minerals may be removed when necessary by
flushing the coil with a cleaner such as “Unlime ® ” or
“Sizzle ® ”.
11.5 High Gas Consumption
Boilers 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, boilers operating with low
CO
2
(especially LP boilers) 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
) can not 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. There is no significant flue
gas odor when combustion is proper. A strong
piercing smell indicates poor combustion and
generally a lean mixture (low CO
2
). Check gas
valve calibration (offset adjustment) and adjust if
indicated. Do not attempt to correct combustion
by reorificing without an O
2
or CO
2
kit
.