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AGE of WATER HEATERS
ALTERNATIVE HOT WATER SOURCES
ANODES & DIP TUBES on WATER HEATERS
ANTI SCALD VALVES
APPLIANCE DIAGNOSIS & REPAIR
APPLIANCE EFFICIENCY RATINGS
AQUASTAT CONTROL Functions
BACKDRAFTING HEATING EQUIPMENT
BACKFLOW PREVENTER, HEATER WATER FEEDER
CARBON MONOXIDE - CO
CHECK VALVES, WATER SUPPLY
CLOGGED SUPPLY PIPING
CROSS CONNECTIONS, PLUMBING
DEBRIS in WATER SUPPLY, Water Heater
DRAIN a WATER HEATER TANK
ELECTRIC WATER HEATERS
FLOODED WATER HEATER REPAIR
FREEZE-PROOF A BUILDING
GALVANIC SCALE & METAL CORROSION
GAS BURNER Flame & Noise Defects
GAS FIRED WATER HEATERS
GAS PIPING, VALVES, CONTROLS
HEATING COST SAVINGS METHODS
HOT WATER SUPPLY
HOT WATER IMPROVEMENTS
HOT WATER DELIVERY SPEED UP
HOT WATER EFFICIENCY IMPROVEMENT
HOT WATER PRESSURE EXPANSION RATE
HOT WATER PRESSURE LOSS
HOT WATER PROBLEM DIAGNOSIS
HOT WATER QUANTITY IMPROVEMENT
HYDROGEN SULFIDE GAS
INDIRECT FIRED WATER HEATERS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
NO HEAT - NO HOT WATER: HEATER DIAGNOSIS
NOISE, WATER HEATER
ODORS IN WATER
PIPING IN buildings, Clogs Leaks Types
RELIEF VALVE LEAKS
RELIEF VALVES - Water Heaters
SCALE REMOVAL, WATER HEATERS
SEWER GAS ODORS
SOLAR HOT WATER HEATERS
TANKLESS WATER HEATERS
THERMAL EXPANSION of HOT WATER
THERMOSTATS, WATER HEATER
TIMERS for ELECTRIC WATER HEATERS
WATER HEATER ALTERNATIVES
WATER HEATER ANODES, DIP TUBES
WATER HEATER AIR INLET
WATER HEATER DEBRIS FLUSH
WATER HEATER DRAIN PROCEDURE
WATER HEATER EFFICIENCY
WATER HEATER FLUSH PROCEDURE
WATER HEATER NOISES
WATER HEATER PROBLEM DIAGNOSIS
WATER HEATER PROPERTIES
WATER HEATER SCALE
WATER HEATER SAFETY
WATER HEATERS for HOME HEATING USE?
WATER ODORS, CAUSE CURE
WATER PIPES, Clogs Leaks Types
WATER PRESSURE TOO HIGH: DANGERS
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER QUANTITY IMPROVEMENT
WATER SOFTENERS & CONDITIONERS
WINTERIZE A BUILDING
Hot water heater properties: this article describes how to compare the operating characteristics such as safety, capacity, life expectancy, and operating cost of alternative methods of providing domestic hot water for washing and bathing.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
Thanks to Carson Dunlop, a Toronto Home Inspection Firm and Home Inspection Educator, for permission to use sketches shown in this article.[Click to enlarge any image.]
Ways to improve total hot water quantity, pressure, temperature and flow are discussed beginning at HOT WATER IMPROVEMENTS
The following individual water heater type articles discuss alternative ways to produce domestic hot water for washing and bathing.
Here is a rough guess at the relative life expectancy of these types of water heaters, provided all other water heater life factors (discussed at AGE of WATER HEATERS) are the same (comments are invited Contact Us) - water heaters are listed in their order of typical life from shortest to longest:
Conditions Affecting Water Heater Life
Keep in mind that conditions besides the type of water heater can dominate its life expectancy. Some of these water heater life expectancy factors include:
For complete information about water heater life and things that affect how long a hot water heater will last, see our full article at AGE of WATER HEATERS.
How to Evaluate the Present and Future Relative Operating Cost of Different Types of Water Heaters: definition of therms
Heating fuel costs vary among different communities, states or provinces, and countries. In most of North America and in some of Europe it's more costly to heat water by electricity than oil and more costly to heat water by oil than gas.
However exceptions occur, especially where one or another energy source is regulated or subsidized by government, or where cheaper sources of electrical energy may be available such as in areas where hydro-electric plants are common.
Certainly, a modern high efficiency oil or gas water heater will cost less to operate than older models of water heater using the same fuel.
Compare the Energy Guide sticker data to compare the relative operating costs of alternative water heaters that you are considering. Our sample water heater energy guide sticker above provides the following data that you can compare among other water heater alternatives:
In the U.S. natural gas is sold to consumers sometimes measured in therms (th). Therms is also used in Energy Guide ratings useful for comparing alternative water heater operating costs.
A therm is the amount of natural gas used to generate 100,000 BTUs of energy.
A therm (th) is thus also a measure of heat content, or a measure of energy usage.
Since this is a simple fixed number, it's easy to compare gas-fired water heater efficiencies.
Example: If water heater A uses 1 therm to produce 100 gallons of hot water heated up from 40 degF to 120 degF, and water heater B uses 2 therms to produce the same 100 gallons of hot water heated up from 40 degF to 120 degF, then water heater A will cost half as much to operate as water heater B. In other words, the fewer therms/gallon or therms/estimated-annual-usage-in-gallons, the higher is the efficiency and lower the operating cost of a given water heater.
In order of cost from least-costly to most-costly to purchase and maintain we estimate this order of types of water heater:
Don't forget that if your plan to change the type of water heater, say from electric to oil or gas-fired, involves changing to use of a new fuel that you do not already have present at the property, extra costs will be involved to install the fuel tank, piping, and controls.
The new LP gas tank installed at this home where a gas fired water heater was installed to replace an electric unit added several hundred dollars to the installation cost.
Be sure to add those infrastructure costs as well as an estimate of the varying rates of change in energy prices among different fuels (electric, gas, oil, solar) into your analysis of the lifetime operating cost estimates when comparing alternative means of making domestic hot water.
Our opinion is that the only energy sources whose price is not going to increase in the coming decades are sources such as solar or wind energy. It is plausible to expect the infrastructure of those systems may actually decline when more people begin to purchase them and their production volume increases.
Hot Water Quantity: A Comparison of the Relative Total Hot Water Capacity of Different Types of Water Heaters
Any water heating method that stores hot water in a tank will provide about the same total hot water capacity if the tank is the same size. This includes electric, gas, oil fired water heaters and side-arm coil water heaters or range boilers, all of which use a water storage tank.
Instantaneous water heaters, also called tankless water heaters, can provide effectively endless hot water but usually in limited quantity to the one or two fixtures supplied by the heater.
Tankless coils provide a more limited quantity of hot water, depending on the amount of heat stored in the heating boiler (a function of its size and materials of construction - steel has less heat storage than cast iron), the temperature of the incoming water, the use of mixing valves, and the flow rate through the coil.
Most tankless coils are rated as capable of providing a specific temperature degree rise across the coil, from input to output, at a specified boiler temperature and at a specified water flow rate in gallons per minute (often 5 gpm). If the water flow rate is faster than specified the coil will not heat water to as high a temperature.
Relative Hot Water Recovery Rate/Speed of Different Types of Water Heaters - What is the recovery rate of a water heater?
The hot water heater recovery speed of a water heating system refers to how quickly the water heater can re-heat incoming cold water.
The standard measure of domestic hot water heater recovery rate is the number of gallons of water than can be heated to 140 degF in one hour. (There must be an underlying assumed-temperature of the incoming water).
A water heater that has a recovery rate of 35 gph will make hot water faster than a water heater that has a recovery rate of only 20 gph.
On newer water heaters you'll see the water heater's recovery rate printed on one of the information labels affixed to the equipment. (Also see
Particularly if your water heater has limited total hot water quantity, and if you expect high hot water usage (such as a large family all wanting to take long hot showers one after another), the recovery speed of the water heater can be an important factor in evaluating its adequacy.
There is some subjectivity in this list. We've encountered a large family of six who said they never ran out of hot water although they were all living in a home whose hot water was provided by a single tankless coil on an old heating boiler.
We've encountered a small family of two adults who complained that they never had enough hot water even though their home was served by a 40 gallon oil-fired water heater.
A lot depends on just how people use hot water: how much at once, how fast the flow, how long the flow per person, etc.
As we illustrate with Carson Dunlop's sketches shown here, in order of speed of re-heating or hot water recovery time, listing slowest-recovery time to fastest recovery time we'd list water heater types as follows:
Don't confuse water heater recovery rates (how fast we can heat water) with water heater operating costs, which we discuss at Water Heater Operating Cost Comparisons. Recovery rate is measured in gallons per hour or gph. Water heater operating costs are compared using a standard measure of energy cost in therms.
See our complete list of water heater safety features and devices found at WATER HEATER SAFETY.
In the LP gas fired water heater shown in our photo, the installer had trouble fitting the draft hood atop the heater since there was then not enough overhead clearance to route the flue out of the building. The installer has thoughtfully left the draft hood he removed, an important safety device, sitting atop the water heater as a reminder that this is an improper installation.
There is just too much subjectivity to make a sensible answer to this question. Some people are frightened by the prospect of a natural or LP gas explosion in a building.
But while it's difficult to set heating oil on fire and so explosions based on the fuel character may be less likely than with an LP or natural gas system, an oil-fired water heater runs at much higher burner and exhaust flue temperatures and so can prevent other types of fire risk.
Most critical in determining the safety of any water heater is that the heater is properly installed and includes the required safety controls such as those responsible for limiting temperature and pressure. Any water heater should include a temperature and pressure relief valve installed of the proper type and at the correct location. Gas-fired devices also should include flue-gas spillage detectors. Oil-fired devices should also include a fire-safety valve that shuts off fuel to the appliance in case of fire.
We guess that proper installation, inspection, and maintenance make more difference in the safety of a water heater than the innate differences among heater types, fuels, etc.
Some Hot water heater safety devices and features
See our complete list of water heater safety features and devices found at WATER HEATER SAFETY. Excerpts are below.
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