What is the Right Size Water Heater?

If it is time to replace your water heater, then you may be wondering what size is the correct size for your house. Of course, there is no one right answer to this question. There are several factors to consider, such as:

• Peak Demand in Gallons per Minute
• Number of People in the House
• What kind of Water Heater (Tank, Tankless, Solar)
• Geographic location of your home

Let’s take a look at some of the common systems and the key criteria to judge the size of the tank.

Tank Water Heating Systems

There are two schools of thought when it comes to how to size a tank system. The first is to use the storage capacity of the tank as a judge of the proper size. This can be good for a rough estimate for your tank. Take into consideration things like:

• How many people are in your home
• How much water is used during the “peak” times such as morning or evening showers
• How much water do appliances use
• How many showers or tubs are in your home
• How cold to winter temperatures get in your geographical area.

There are many charts online that will point to a size based solely on the number of people in the home as well. Again, this is a good rough estimate but does not really take into consideration full peak usage.

Using the First Hour rating can be a more accurate judge of what size tank you need. Take some time to calculate what the peak usage for your home is in an hour. Add up any multiple showers, bath tubs, sinks or appliances that might all be run at the same time. Then use this number as a basis for the size of your hot water heater.

Tankless Systems

On Demand or tankless systems require a bit of a different method to judge size. Those systems are typically rated in temperature rise per minute for a flow rate of water. This means that you will need to do a few calculations.

First, figure out what your peak demand of water is. Look at your flow rates for your sinks and shower heads to determine this number. Typical numbers are 2 gallons a minute for a shower head or .5 gallons per minute for faucets. So if you have two showers and a sink that might be running your number would be 4.5 gallons per minute.

Then you will need to figure the average temperature of the water coming into the house. A good system will give you a 70 degree temperature rise at a flow rate of 5 gallons per minute. This means in the winter, your hot water would be around 102 degrees.

Do you need help buying or installing a new water heater? Click here to get free custom quotes from reputable hot water heating system contractors in the Philadelphia area. You’ll receive custom quotes without having to invite contractors to your home!