LAARS Mighty Therm LO-NOx VW (Sizes 250/400) - Installation, Operation and Maintenance Instructions - Manual (Page 10)

LAARS Heating Systems Page 10
Mettre l’appareil inspecté en marche. Suivre les
instructions d’allumage. Régler le thermostat de
façon que l’appareil fonctionne de façon
continue.
5. Test for spillage at the draft hood relief opening
after 5 minutes of main burner operation. Use the
flame of a match or candle, or smoke from a
cigarette, cigar or pipe.
Faire fonctionner le brûleur principal pendant 5
min ensuite, déterminer si le coupe-tirage
déborde à l’ouverture de décharge. Utiliser la
flamme d’une allumette ou d’une chandelle ou la
fumée d’une cigarette, d’une cigare ou d’une
pipe.
6. After it has been determined that each appliance
remaining connected to the common venting
system properly vents when tested as outlined
above, return doors, windows, exhaust fans,
fireplace dampers and any other gas burning
appliance to their previous conditions of use.
Une fois qu’il a été déterminé, selon la méthode
inidquée ci-dessus, que chaque appareil raccordé
au système d’évacuation est mis à l’air libre de
façon adéquate. Remettre les portes et les
fenêtres, les ventilateurs, les registres de
cheminées et les appareils au gaz à leur position
originale.
7. Any improper operation of the common venting
system should be corrected so the installation
conforms with the National Fuel Gas Code, ANSI
Z223.1. When resizing any portion of the
common venting system, the common venting
system should be resized to approach the
minimum size as determined using the
appropriate tables in Appendix G in the National
Fuel Gas Code, ANSI Z223.1.
Tout mauvais fonctionnement du système
d’évacuation commun devrait être corrigé de
façon que l’installation soit conforme au national
Fuel Gas Code, ANSI Z223.1 et (ou) aux codes
d}installation CSA-B149.1. Si la grosseur d’une
section du système d’évacuation doit être
modifiée, le système devrait être modifié pour
respecter les valeurs minimales des tableaux
pertinents de l’appendices F du National Fuel
Gas Code, ANSI Z2231.1 et (ou) des codes
d}installation CSA-B149.1.
2.6 Water Flow
2.6.1 Water Chemistry
Laars equipment is designed to be used in a
variety of water conditions. With the proper pump, the
water velocity in the heat exchanger tubes is kept high
enough to prevent scaling from hard water, yet low
enough to avoid erosion by soft water.
Hardness Grains per Parts
Category Gallon per Million
Soft 1 through 7.5 17 through 128
Normal 7.6 through 17 129 through 291
Hard Over 17 Over 291
Table 3. Water Hardness.
NOTE: It is possible to have hard and soft water in the
same city. Check with the local water companies.
If an installer sees damage to any water handling
equipment at the installation site, it should be repaired
as soon as possible to help reduce maintenance costs.
If there is erosion, resize the pump to reduce water
velocity before the tube ruptures. If scaling is bad, set
up a heat exchanger tube-cleaning maintenance
schedule to prevent heat exchanger tube cracking and
wear. Not fixing the condition will mean serious
damage to the heater and the water system.
NOTES: In areas where the water supply is soft or
corrosive, the heater must have cupronickel tubes in
the heat exchanger. Laars does not warrant heat
exchangers damaged by scaling, corrosion, or
erosion.
2.6.2 Water Hardness
Consider the water hardness when selecting a
pump for the heater (see Table 3). Hard water needs a
pump which can provide high flow to prevent scaling,
while soft water needs low flow to prevent erosion.
2.6.3 Freeze Protection
Although VW, PW heaters are design-certified
for outdoor installations, such installations are not
recommended in areas subject to freezing temperatures
unless proper precautions are taken.
Power outage, interruption of gas supply, failure
of system components, activation of safety devices,
etc., may prevent a heater from firing. Any time a
heater is subjected to freezing conditions, and the
heater is not able to fire, and/or the water is not
able to circulate, there is a risk of freezing in the
heater or in the pipes in the system. When water
freezes, it expands. This can result in bursting of pipes
in the system, or damage to the heater, which could
result in leaking or flooding conditions.
2.6.4 Pump Requirements
PW heaters are equipped with factory-mounted
and wired pumps. The pump is for heater-to-tank
circulation only. See Table 4 for pump performance.
PW heaters are not available for hard water applications.
VW and PW heaters are not designed for applica-
tions where the temperature of the water flowing
through the heater remains below the dew point, 110°F
(43°C).
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