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Let's Talk Hot Water – 8/9/13

Conventional residential water heaters come in three basic types:

1) Electric

2) LP or natural gas fired gravity vent

3) LP or natural gas fired power vent

If you are replacing an exiting water heater, you may be limited by what was originally installed.

Electric is least expensive to purchase and install requiring two pipe connections and one electric connection  It is the most expensive way to heat water.  

If you do not heat many gallons of water, it is a good choice. Electric can almost always replace an LP or natural gas fired water heater.

LP or natural gas fired gravity vent water heaters are more expensive to purchase and install than electric, but heat water more cost effectively.  Gravity 

vent water heaters typically vent cumbustion gases through roof.  If you are replacing a gravity vent water heater, capacity of new water heater may be 

restricted by what size vent is in place.  If you are installing in new construction, size vent pipe for largest imaginable water heater (typically 4" vent pipe).

LP or natural gas power vent water hearters are more expensive to purchase and replace than choices above, but may be less expensive than gravity 

vent to install in new construction.  Power venting eliminates need for venting through roof.  Combustion gases are exhausted by a fan (power vent) through 

a side wall using plastic (pvc) pipe.  Some people do not like power vent water heaters because they can hear venter fan run while water is being heated.  

If you are noise sensitive and are building new construction and are using LP or natural gas for heating water, make sure your builder knows you want 

gravity vent.  Power vent motors can fail before rest of water heater, they can be expensive to replace.

Once you have selected what type of water heater is right for you, you are ready to select what size.  Water heaters have two critical specifications:  

1) Number of gallons available first hour

2) Recovery rise, typically 90F gallons - how many gallons heater can heat 90F in one hour.

Consider how many people will be using your water heater and what type of fixtures use hot water.  If you have a large capacity tub and need to have 

hot water avaiable shortly after filling your tub, you will need a lot of hot water capacity.  Your plumber should be able tohelp you select suficiant capacity.

Electric water heaters size for size have lower first first hour and recovery rise ratings.

Above are practical consideration for selecting a conventional residential water heater.

Nest time, I will review ways to heat water other than with a conventional residential water heater.

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