Water Heater Guide - Major Types Compared

Which water heater is the right one for my application with active or passive solar, gas storage, electric storage, tankless gas or electric, heat pump and others to choose from.

There are a number of ways to heat water and a variety of fuels to choose from.  Where you live is factor in determining what kind of water heater is best for you because of the influence of ambient air and water temperatures and fuel availability.

In order to determine what the best water heater for your situation is you need to define exactly what you are looking for.  What are the most important things for you… it won’t be the same for everyone.

The things you must consider include initial cost of the system, cost to heat water, reliability, maintenance, physical size, venting requirements if applicable, safety, fuel type, amount of hot water needed during peak usage periods, and freeze protection issues.

One of the first things you need to decide is what type of fuel it will burn and often you won’t have a choice.  The least expensive fuel would of course be solar energy. 

Solar Powered Water Heating

Solar water heaters can provide you with plenty of hot water if you are in a geographical location that receives a lot of solar energy.  Living near the equator helps.  Constant cloud cover does not. 

Solar water heaters can vary in cost from very inexpensive home made batch heaters to sophisticated indirectly heated systems with separate storage and solar panels.  You can make a simple one for a few hundred dollars, or spend thousands of dollars on one of the high tech systems.

With the more sophisticated systems maintenance and repair can become an issue.  A few years from now there may be no parts or service available, and repair costs can be quite high.

Electric Water Heaters

Electricity is the most expensive fuel your water heater can use.  Believe it or not, electric water heaters are very efficient, much more so than gas water heaters.  With a gas water heater some of the heat produced by the burners goes up the flue instead of into the water.  With an electric water heater the heating elements are totally inside the water heater surrounded by water.  All of the heat goes into the water.  Electric water heaters are generally about 99% efficient.

The reason it is the most expensive way to heat water is that on average only about 30% of the electricity generated makes it to your home.  The rest gets used up by transmission line and other losses.  This makes electricity more expensive than gas on an energy content basis.

Using electricity to heat water is slower than with gas, taking about twice as long with a typical water heater as a gas water heater would take.  With electric units, to heat the water faster would require more energy per unit time… which means more amps. 

Electric water heaters have one thing going for them, simplicity.  A couple of electric resistance heating elements and thermostats and you’re good to go.  Not much to go wrong; most often a leak in the tank after many years of service.  As far as I am concerned, a leaky tank is the best mode of failure.  You see a puddle forming and you can arrange for a replacement before you actually have a problem getting hot water.

To carry more amps you need larger wiring.  This becomes a problem for tankless water heaters since they must heat the water much more quickly than a storage tank type unit.

Heat Pump Water Heaters

Heat pump water heaters use less energy standard electric water heaters because they don’t produce heat; they transfer heat in the air to the water in the tank.  It takes less electricity to move the heat around than to generate it.  However, there must be heat in the air to move, so if the air temperature is too low, the heat pump becomes inefficient or looses the ability to heat the water.

Some heat pumps use ground water to obtain heat instead of the surrounding air.

Heat pump water heaters have a very high initial cost several times that of a traditional gas or electric water heater, and they heat the water much more slowly than a typical electric storage water heater.

Gas Water Heaters

Gas water heaters are usually the least expensive method of heating water due to the low cost of gas compared to electricity. This applies only if you happen to have access to natural gas though. 

Propane gas water heaters are pretty much the same as natural gas water heaters as far as efficiency goes, the main difference being the cost of the gas. Propane can be fairly expensive.

 Like standard electric water heaters, gas water heaters are fairly simple and thus are pretty darned reliable.  As with the electrics a tank leak is often the first sign of a problem and water heater replacement the solution.

Electric Tankless Water Heaters

Electric tankless water heaters are generally small due to the high amount of energy required to rapidly heat flowing water.  However, there are advantages to electrics such as no venting to worry about, no pollution in your home, no chance of carbon monoxide poisoning, small size, and silent operation. 

We mustn’t forget about the ability to provide endless hot water as long as you don’t exceed the maximum flow rate and the higher energy efficiency due to the absence of standby losses.

On the negative side, you must maintain a minimum flow rate to keep the water heater from shutting off, typically one half gallon to three quarter gallons per minute.  This means you won’t be able to run a trickle of warm water, you will need to run a flow that will be substantially above the minimum flow rate to turn on the heater.  This can be quite wasteful of water.

The maximum amount of hot water available from the heater is limited by the maximum energy input, and if the maximum flow rate is exceeded the temperature at the outlet will begin to drop.  Careful attention must be given to selecting the proper size heater for your application.  Normally tankless companies provide a chart showing the maximum flow rate for any given temperature rise.  When using these tables you should use the inlet water temperature that you have during the winter months.

Electric tankless hot water heaters are more expensive than storage tankless heaters and usually will require a dedicated 220 volt service line be installed if you want enough hot water for a shower.  They are also more complex than standard heaters and will probably be more likely to suffer a breakdown, harder to find a qualified service company, and more expensive to repair.

Gas Tankless Water Heaters

Gas is the preferred choice for tankless water heaters because with gas you can heat the water more quickly than with electrics allowing substantially larger flow rates. This is important especially for whole house tankless water heaters.

The advantages of a gas tankless unit are endless amounts of hot water, higher overall efficiency than storage water heaters due to the elimination of standby losses due to no storage tank, and smaller footprint than a tank type unit.

Disadvantages include increased delivery time for hot water, high minimum flows from the fixture to achieve a desired warm to hot temperature, increased gas line size in existing tank type installations, increased vent size, and higher repair costs.  Most gas tankless hot water heaters also have sophisticated electronic controls and thus will not operate if there is a power outage.   Some models generate their own electricity from the flowing water and are immune to the power outage problem.

Gas tankless hot water heaters are considerably more expensive than traditional storage types and should any thing go wrong they are expensive to repair.  It’s also harder to find experienced service people for tankless units.

Hot Water Demand Pumps

Whatever technology you end up with, if you have long pipe runs or long waits for hot water, and you have to run water down the drain while you wait for the hot water to arrive, then you should consider installing a hot water demand system pump. 

Demand hot water systems work with any type of water heater, and will save you time, water, and money. They use very little electricity to operate, typically about $2.00 per year.

Save thousands of gallons of water every year by adding a demand pump to your storage type, tankless, or solar water heater.

Chilipepper Sales 1380 Greg St., # 221 Sparks Nevada,      89431       PH (775)-359-1223