Reliant FVIR GAS WATER HEATER Technical Information PDF herunterladen (Seite 70)

RESIDENTIAL GAS AND ELECTRIC WATER HEATER

TROUBLESHOOTING and SERVICE HANDBOOK

RELIANCE Water Heater Company Technical Training Department

Subject: Venting Techniques that Eliminate Pilot Outage

A clean heater, and heater environment, is the first thing that should be considered when troubleshooting

a water heater. Higher efficiency water heaters and new government regulations for flammable vapor

ignition resistance have changed the design of water heaters. Dirty environments can take there toll on a

water heater. Take time to make sure that the area around, and under the heater is clean and obstruction

free. Make sure that the air intake screen (LDO screen) located on the base ring of the heater is clean

and properly installed; this is where all of the combustion air enters the heater. Cleaning the screen and

under the heater can improve the performance of the heater and save a costly service call. Please visit

www.reliancewaterheaters.com

for cleaning instructions and other service related material.

Venting systems are very important to the safe operation of the water heater. For example, a 90 elbow

on the top of the heater’s draft hood can reduce the vent efficiency by up to 50%. There should be a rise

of ten vent diameters off of the top of the heater before the first elbow. On a heater that has a three inch

vent that would be 30 inches before an elbow. A poorly designed vent can render the heater useless and

could lead to serious injury or death. A good vent is a vent that rises straight up from the heater to the

termination on the roof and continues outside for at least another two feet straight up. However,

horizontal vent runs are acceptable as long as a few rules are followed.

¾ The horizontal vent run (any angle less than 45° from horizontal) should not exceed 75% of

the vent height. (The distance from the top of the heater straight up to the altitude of the vent

termination).

¾ The vent must have a minimum of ¼” inch per foot rise on the horizontal run meaning

that every four foot continuous run of a horizontal pipe must rise at least one inch.

¾ Must not be vented with a power vented (fan assisted) appliance per the National Fuel Gas

Code. 10 vent diameters off of the top of the heater before the first elbow.

¾ The vent must be sized to handle the total BTU input of all the appliances connected.

If there is more than one appliance connected to the vent system and you suspect a problem, call a local

plumber or venting specialist. Rust forming on the heater jacket and burnt gas are signs that the vent is

not working properly. An improper vent may spill flue products out of the top of the heater which could

cause the heater and vent pipe to rust.

As the water heater in most new homes has been banished to the garage, basement, closet or attic,

simple needs of water heaters have been forgotten or overlooked. The most common is the availability of

needed combustion air. Gas burning appliances must have air (Oxygen) to sustain a flame, and water

heaters in garages and attic or utility closets have plenty of air around them; right? As we will explain that

is not always the case. There are three major reasons for pilot outage; Capping, High ambient

temperature and decompression. Though the outcome is the same, the causes of “Pilot Snuff” are quite

different. “Pilot Snuff” is the lack of buoyancy in the gases causing them to lie in the bottom of the heater

until the flame runs out of oxygen and goes out. Let’s look at the cause and effect of these three different

types of pilot outage. Let start with “Capping.”

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Reliant FVIR GAS WATER HEATER Technical Information Seite 70