THOR GH105-N, Техническое и сервисное руководство

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Trouble shooting
16
BURNER PROBLEMS– cont’d.
FLOATING FLAMES:
The difference between floating flames and lifting (or blowing) flames should be clearly understood. Both
conditions are undesirable, but the causes and corrective steps are different. Floating flames are lazy
looking. They do not have well defined cones, and appear to be “reaching” for the air. They are long, ill-
defined, quite flames which roll around in the combustion chamber sometimes completely off the ports.
Usually a strong aldehyde odor is present. Floating flames almost always indicate incomplete combustion.
They point to a dangerous condition which require prompt correction. If secondary air supply is reduced
too far burner flames will float. Combustion products above the burner re-circulate lower in the chamber.
These products contaminate the air supply, adding to the problem. A lack of combustion air causes
burner flames to float. Several conditions, or a combination of these conditions can be the cause. The
appliance may be overrated. If so, the flue outlet area provided for the rated input may be too small for
the increase gas rate. Check appliance rate and reduce if necessary. Other conditions may cause poor
venting and lead to floating flames. Soot or dust may be blocking flueways. Check flueways and clear any
blockage found. Determine, if possible, the reason the flueways blocked up. Check for blockage of
burners, and clean them if necessary. Adjust primary air to get rid of any yellow tipping which may have
produced soot to block he flueways. Make sure secondary air inlet openings are not blocked. Reduced
natural draft (venting) through an appliance may take place when it is operated from a cold start. Some
floating flames may appear for a brief time until draft is established. When the appliance heats up it
should operate in a normal manner.
UNSTABLE OR WAVERING FLAMES:
Drafts across burners may cause flames to waver or appear to be unstable. This condition should not be
confused with lifting or floating flames. Wavering burner flames can lead to incomplete burning if flames
impinge on cool surfaces. Pilot flames under drafts may go out, or they may be diverted from heating the
sensing element of the automatic pilot device. In either case the automatic pilot will shut off gas supply
to the appliance. Drafts affecting pilot flames may be simply external drafts, such as across the floor.
Protect the pilot flames with suitable baffles. Draft-blown main burner flames may indicate a more
serious problem, such as cracked heat exchanger. Replace or repair a cracked heat exchanger without
delay.
GAS ODOR AT PRIMARY AIR OPENINGS:
Under normal burner operation, a negative pressure (vacuum) should exist inside the primary air
openings of a burner, drawing in air. If all gas fed to the burner by the orifice does not flow to the burner
head, some gas may spill from the primary air openings. If this condition is found, check the burner body
for restrictions, and check the orifice to make certain it is not out of line.
CORROSION OF APPLIANCES:
Gas appliances are designed and built to give long dependable service life. In some installations recently,
usually severe corrosion has occurred resulting in customer complaints. This corrosion is attributed to the
extensive use of aerosol propellants, hydrocarbons which contain the elements FLOURINE AND CHLORINE.
These elements are called halogens. Halogens in their free state are very corrosive. When the
propellants pass through a flame, they break down and the halogen gases are released. In combination
with the water vapor in the flue gases they cause corrosion in heat exchangers, flueways and other
appliance parts. Some of the worst cases of this corrosion have been in beauty shops where hair sprays
are used and in dry cleaning plants where halogen-containing materials are used as cleaning fluids.