Operational Conditions

Excessive condensation may be noticed during the winter and early spring months when incoming water temperatures are at their lowest.

Good venting is essential for a gas ﬁred water heater to operate properly as well as to carry away products of combustion and water vapor.

SMOKE / ODOR

It is not uncommon to experience a small amount of smoke and odor during the initial start-up. This is due to burning off of oil from metal parts, and will disappear in a short while.

THERMAL EXPANSION

As water is heated, it expands (thermal expansion). In a closed system, the volume of water will grow. As the volume of water grows, there will be a corresponding increase in water pressure due to thermal expansion. Thermal expansion can cause premature tank failure (leakage). This type of failure is not covered under the limited warranty. Thermal expansion can also cause intermittent temperature-pressure relief valve operation: water discharged from the valve due to excessive pressure build up. The temperature- pressure relief valve is not intended for the constant relief of thermal expansion. This condition is not covered under the limited warranty.

A properly sized thermal expansion tank should be installed on all closed systems to control the harmful effects of thermal expansion. Contact a local plumbing service agency to have a thermal expansion tank installed.

STRANGE SOUNDS

Possible noises due to expansion and contraction of some metal parts during periods of heat-up and cool-down do not necessarily represent harmful or dangerous conditions.

Condensation causes sizzling and popping within the burner area during heating and cooling periods and should be considered normal. See “Condensation” in this section.

SMELLY WATER

In each water heater there is installed at least one anode rod (see parts sections) for corrosion protection of the tank. Certain water conditions will cause a reaction between this rod and the water. The most common complaint associated with the anode rod is one of a “rotten egg smell” in the hot water. This odor is derived from hydrogen sulﬁde gas dissolved in the water. The smell is the result of four factors which must all be present for the odor to develop:

a.A concentration of sulfate in the supply water.

b.Little or no dissolved oxygen in the water.

c.A sulfate reducing bacteria which has accumulated within the water heater (this harmless bacteria is nontoxic to humans).

d.An excess of active hydrogen in the tank. This is caused by the corrosion protective action of the anode.

Smelly water may be eliminated or reduced in some water heater models by replacing the anode(s) with one of less active material, and then chlorinating the water heater tank and all hot water lines. Contact the local water heater supplier or service agency for further information concerning an Anode Replacement Kit and this chlorination treatment.

If the smelly water persists after the anode replacement and chlorination treatment, we can only suggest that chlorination or aeration of the water supply be considered to eliminate the water problem.

Do not remove the anode leaving the tank unprotected. By doing so, all warranty on the water heater tank is voided.

“AIR” IN HOT WATER FAUCETS

HYDROGEN GAS: Hydrogen gas can be produced in a hot water system that has not been used for a long period of time (generally two weeks or more). Hydrogen gas is extremely ﬂammable and explosive. To prevent the possibility of injury under these conditions, we recommend the hot water faucet, located farthest away, be opened for several minutes before any electrical appliances which are connected to the hot water system are used (such as a dishwasher or washing machine). If hydrogen gas is present, there will probably be an unusual sound similar to air escaping through the pipe as the hot water faucet is opened. There must be no smoking or open ﬂame near the faucet at the time it is open.

HIGH WATER TEMPERATURE SHUT OFF SYSTEM

This water heater is equipped with an automatic gas Shut-off system. This system works when high water temperatures are present. Turn “OFF” the entire gas supply to the water heater. The high temperature Shut-off is built into the gas control valve/thermostat. It is non-resettable. If the high temperature Shut-off activates, the gas control valve/thermostat must be replaced. Contact a qualiﬁed technician.

FMD 40, FMD 50, 315795-000 MH, FMD 30 specifications

A.O. Smith is a renowned brand in the field of water heating solutions, offering a range of efficient and durable water heaters tailored to meet diverse consumer needs. Among its extensive lineup, the A.O. Smith FMD series showcases several commendable models, including the FMD 30, FMD 40, and FMD 50, each boasting unique features and advanced technologies.

The A.O. Smith FMD 30 is a compact water heater designed for smaller households or limited spaces. With a 30-gallon capacity, it is engineered to provide ample hot water for everyday needs such as bathing, washing dishes, and laundry. The heater employs advanced insulation technology, ensuring heat retention and energy efficiency. The thermostatic control system allows users to easily adjust the water temperature to their preference, ensuring comfort while promoting safety.

Moving to the A.O. Smith FMD 40, this model offers an increased capacity of 40 gallons, making it an ideal choice for medium-sized families. It incorporates A.O. Smith’s cutting-edge Durapower glass coating, which protects the tank from corrosion, ultimately extending its lifespan. The FMD 40 also features an enhanced heating element design that ensures rapid heating and consistent water temperature, making it perfect for bustling households.

The A.O. Smith FMD 50 takes things a step further, providing 50 gallons of hot water storage and designed for larger families or high-demand applications. This model integrates advanced technology features like a smart thermal control system that optimizes energy usage, ensuring that hot water is available when you need it without unnecessary power consumption. With robust construction materials, the FMD 50 is built to last, even in harsh conditions.

All models in the A.O. Smith FMD series prioritize user convenience. They come equipped with easy-to-read digital displays for monitoring temperature and status, along with built-in safety features such as automatic shut-off mechanisms. Installation is straightforward, and each unit adheres to energy efficiency standards, which help reduce utility bills while being environmentally friendly.

In summary, the A.O. Smith FMD series, including the FMD 30, FMD 40, and FMD 50, represents a commitment to quality and innovation. With their varying capacities and advanced technologies, these water heaters cater to a wide range of household needs, delivering reliable hot water solutions while maintaining energy efficiency and durability. Investing in an A.O. Smith FMD water heater not only guarantees comfort but also highlights a commitment to sustainability.