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Right-Sizing Your Water Heater: A Key to Lower Bills (and Long, Hot Showers) Part 2

Posted: March 9, 2017

Hot water knob

Part Two of Two

In Part One of this two-part post, we talked about the importance of peak demand in helping to size a propane water heater for use in your home. Here in part two, we’ll discuss two other concepts in right-sizing: Storage capacity/Hot Water Flow Rate and Inlet Temperature.

Capacity and hot water flow rate
Measuring how much hot water your water heater can produce depends on the type of equipment you have. For a water heater with a tank, the most important factor in sizing is storage capacity – basically, the size of the tank itself. An important concept related to capacity is recovery rate, which measures how long it takes your water heater to refill with hot water. A small unit with a high recovery rate could out-perform a large unit with a slow recovery rate.

In propane tankless water heaters, the most important sizing factor is hot water flow rate – how many gallons of hot water per minute your water heater can produce and distribute. While tankless water heaters can’t technically “run out” of hot water, the flow rate of an improperly sized unit could slow to a trickle.

Inlet temperature
The third factor to consider in sizing a system is the temperature of water coming into your home – called the inlet temperature. To heat water to acceptable temperatures for a hot shower during a very cold winter, your system may need to heat the water 60 degrees or more– which means you’ll need more BTUs to reach that temperature than in the summer.

Putting it all together
To find the right sized water heater for your home, calculate your peak demand, then find a tank capacity that will meet that need at the coldest time of the year – that is, when the difference between the inlet and outlet water temperatures is highest. In a tankless system, you’ll want to make sure the hot water flow rate of the water heater is high enough to meet peak demand when inlet temperatures are lowest.

If you need help sizing your water heater – or if you think it might be time for a new, high-efficiency unit for home – let us know. Our experts will help you choose from our selection of propane water heaters, and even give you a FREE estimate!