When it comes to water heater needs for your house, you have to consider more than merely the size of your household, as the house’s square footage is also an important factor. Water heaters that are too small are overworked and run low on hot water, while ones that are too large waste energy. Dahme Mechanical Industries, Inc is here to help you find the water heater you need for your home.
Where Do I Start?
Start the research process by reviewing broad guidelines for water heater sizing and familiarizing yourself with specifications like efficiency and performance. In addition to energy use, warrantees, and cost, make sure your new water heater meets your household’s daily needs. Consider the following factors:
- Family size.
- Hot water usage habits.
- The FHR, or first-hour rating.
- Whether you want a standard or a tankless water heater.
These are some of the most important factors when selecting a water heater. The FHR shows how many gallons of hot water are available over an hour when starting with a full tank. This rating helps determine if the water heater meets or exceeds your needs based on family size and water usage habits. A tankless water heater may be an option for households with limited hot water use or usage spread out over the day. They cost more but are also more energy-efficient.
What Is Your Family’s Peak Usage?
While family size can provide rough guidelines for water heater needs, peak usage and overall usage of hot water are far more critical factors. Consider a larger water heater if you commonly use two to four appliances that require hot water simultaneously.
Explore your family’s hot water usage, noting peak times, to determine which water heater would best meet your needs without being too large and thus wasting energy. Selecting a water heater that’s too small can result in running low on hot water as well as reducing its life span by overuse.
Watch for the FHR which calculates 70% of the tank capacity plus the recovery rate, or the rate at which the water heater can replenish hot water. This calculation uses 70% of the tank’s capacity since hot water is replaced with unheated water during use. Find the peak usage hour of the day and add up the numbers. Look for a water heater with an FHR rating within a gallon or two of your expected peak demand.
After peak usage, it takes time for the water heater to recover and heat all the water it holds. Incoming water temperature, water heater size, and fuel type affect how long it takes to heat water. An 80-gallon gas water heater could take an hour to reheat, while an electric water heater of the same size could take two hours to heat up.
What Is the Difference Between Tank and Tankless Water Heaters?
Traditional tank water heaters are designed to hold a tank full of hot water, about 20 to 80 gallons, and can provide a significant amount of hot water right away. Tankless water heaters, on the other hand, heat incoming water on demand, requiring buyers to consider flow rate and temperature rise instead of tank size. Both water heater styles have electric and gas-powered versions.
Flow rate is the gallons per minute of hot water needed. Most on-demand heating systems provide 1 to 5 gallons of hot water per minute. Determining your minimum flow rate needs is similar to determining tank size requirements. Keep in mind that maximum flow rates are affected by the incoming water temperature, meaning that colder climates may experience seasonal changes in performance.
Temperature rise is a measure of how many degrees the water needs to be heated to before it reaches the appliance or spigot. Temperature rise varies depending on the climate and season. It’s easy to determine cold water temperature, just measure the temperature after letting the water run for a couple of minutes.
Pros and Cons of Tankless Water Heaters
Tankless water heaters, like any appliance, have their pros and cons. Pros include their compact size, efficiency, long-term savings, and environmental friendliness. Tankless water heaters can be between 8% and 50% more efficient than their tank counterparts since they don’t have to maintain a large reserve of hot water.
Cons of tankless water heaters include a limited flow rate, a higher upfront cost, and possible adaptation of plumbing and utilities to install. Tankless water heaters may not work for homes that use over 40 gallons of hot water daily, but point-of-use tankless water heaters may be installed for high-use appliances. Tankless water heaters can cost up to three times more than comparable traditional tank model.
FAQs About Water Heaters
How big of a water heater does my family need?
- One to two people: 30-40-gallon water heater.
- Two to three people: 40-50-gallon water heater.
- Three to four people: 50-70-gallon water heater.
- Five or more people: 60-80-gallon water heater.
What are my hot water usage habits?
Peak usage, determined by adding overlapping activities during a peak hour, is a key factor in determining your hot water usage habits. You should consider spreading out high-usage activities like showers, laundry, and running the dishwasher.
How much hot water do certain activities use?
- Shower: 10-20 gallons.
- Dishwasher: 6-14 gallons.
- Hand-washing dishes: 4-10 gallons.
- Washing clothes, standard top-loader: 27-40 gallons.
- Washing clothes, front-loaders and high-efficiency top-loaders: 14-27 gallons.
How many gallons per minute do certain activities use (this is targeted to tankless water heaters)?
- Sink: 1 gallon per minute.
- Bathtub: 3 gallons per minute.
- Shower: 2.5 gallons per minute.
- Dishwasher: 3 gallons per minute.
- Clothes washer: 3 gallons per minute.
What temperature should I set my water heater at?
Most people are comfortable at 120 degrees, but you can set you water heater at any temperature that makes your family most comfortable.
Choosing the right water heater for your household is an important decision that will affect utility and maintenance bills for years to come. Consult the experts at Dahme Mechanical Industries, Inc. Their knowledge and experience will help you decide on the style and size of the water heater needed for your family and home needs. Our technicians are also here to help with water heater installations, repairs, and replacements!