Hot Water Heaters
Readily accessible hot water is one of life’s basic necessities. Tank-style hot water heaters are a model of simplicity and provide years of reliable service. The process of heating water is not particularly complex; a gas, electric or oil burner raises the temperature of a fixed amount of water, which is stored in a tank until it is needed.
When purchasing a water heater, it is important to recognize two key components that affect availability and energy costs.
- Capacity: Choosing a water heater with sufficient capacity is critical to ensure every member of the household has an instant supply of hot water on demand. Capacity is measured by the "first hour rating," which is calculated as a function of the tank size relative to the speed at which the water is heated.
- Efficiency: All water heaters are rated according to the Energy Factor (EF) standard, which allows consumers to compare the efficiency of different brands and models of water heaters. The factor is derived from a formula that measures the amount of heat energy extracted from the unit divided by the amount of energy it consumes. A higher EF factor is associated with greater heating efficiency.
Gas Water Heaters
Gas fired hot water heaters are the most common water heating appliance. They work by transferring heat through convection currents. Cold water enters a storage tank through a device called a dip tube and accumulates at the bottom of the tank. In gas water heaters, a sensor detects when the water temperature has fallen below a predetermined threshold. A signal is sent to an igniter that activates a burner housed in a combustion chamber. The resulting thermal energy is transferred through a core within the tank, which subsequently heats the surrounding water.
Since hot water is less dense than cold water, it rises to the top of the tank where it is routed through a hot water discharge pipe and ultimately delivered to a plumbing fixture somewhere in the building. Waste byproducts from the burn cycle are vented to the outdoors through a specially-designed flue pipe.
Oil Water Heaters
Oil fired hot water heaters share many of the same design characteristics of their gas counterparts. While the tank assembly operates in essentially the same manner, direct oil fired water heaters are distinguished by a unique burner assembly. Oil is mixed with air and injected into a power burner as an atomized mist. An electric spark ignites the mixture and a concentrated flame is propelled into an adjacent chamber where heat is transferred to a core inside the storage tank.
Indirect Fired Water Heaters
Both indirect gas fired water heaters and indirect oil fired water heaters use a water–to-water heat exchange process. Thermal energy originating from an external boiler is circulated through a coil in a separate, adjacent storage tank. The hot water stored in the tank allows the boiler to cycle less frequently, which can save substantially on fuel bills.
Indirect water heaters offer exceptional EFs, usually in the .8 to .9 range. Warranties often extend up to 20 years, which is considerably longer than most direct fired appliances. Since the heating process is indirect, minerals have a tendency to remain in suspension rather than accumulating at the bottom of the tank, which is a characteristic of direct fired water heaters.
Is a Gas or Oil Water Heater Right for Me?
In general, direct gas fired water heaters are more efficient than oil fired models with a similar capacity. The total cost of installation and operation may be more than 50 percent higher over the life of the equipment. Oil based water heaters usually have a shorter lifecycle when compared to gas, largely due to the complexity of the burner assembly.
The primary advantage of direct fired oil water heaters is their recovery ability. The concentrated flame in the burn process can heat incoming cold water three to four times faster than other fuels. In large families, this can be an important advantage.
For buildings with an existing boiler used for space heating, an indirect system may be an appropriate choice, regardless of the fuel type. In cooler temperatures when the boiler is running frequently, indirect water heaters provide abundant hot water with minimal associated cost.
The Brand We Represent
Since 1929, Bock water heaters have set the standard for reliability, efficiency, and low operating costs. Both direct and indirect models are available and Bock manufactures products for oil, gas, and dual fuel applications. You can find information about Bock water heaters and a variety of other HVAC related products on the Griffith Energy Services’ homepage.