How Long Does a Water Heater Take To Heat Up?

Property owners in New York City must ensure tenants have an adequate hot water supply. This supply depends on the water heater output and size, but how long does a water heater take to heat up the water to begin with? Many factors go into the overall effectiveness of a water heater. Discover what contributes to heating times and how to preserve the supply of hot water for all your tenants.

How Long Does a Water Heater Take To Heat Up: 5 Factors Affecting Heating Time

1. Type of Water Heater

An average-size residential water heater takes between 30 and 80 minutes to heat up, depending on its fuel source and tank size. That said, the type of water heater or heating system your building uses plays a crucial role in the hot water supply and the time to heat.

A centralized system is relatively common in an apartment building and typically includes one or more centralized heaters. A standard centralized system includes tanks, heat pumps, and boilers and uses electricity, natural gas, or, less commonly, propane to heat the supply. In some modern systems, you can use solar power for heating.

Some buildings have individual unit heaters instead. While both individual and centralized systems usually depend on reservoirs for hot water, it is also common to find tankless water heaters in individual units. Tankless heaters are more expensive to install and maintain. However, they reduce the heating time for water and ensure a continuous hot water supply at so many gallons per minute.

While tankless water heaters are efficient with individual apartments, especially for on-demand hot water, they struggle to supply multiple units. Peak times of hot water usage can be especially difficult for tankless systems trying to serve too many tenants at once.

For apartment buildings, individual-unit water heaters are likely your best and most efficient option. The units reduce heating time, and as long as you appropriately size them for the apartments, tenants should have a continuous hot water supply when needed.

2. System Size

System size contributes to how long a water heater takes to heat up. The capacity is also critical to meeting apartment building or unit demands. The most important part of water heater selection is finding a balance between tenant needs, operating costs, and appliance lifespan. To determine the right size for your complex, you must calculate the building’s load.

A load calculation factors in the number of apartments in the building, number of bathrooms per unit, types of fixtures, and estimated peak usage patterns. A professional plumber from Calray Boilers can help you get the correct numbers to figure out water heater size and demands.

Water heater capacity matters for its heating time. An undersized water heater can’t heat fast enough and will run out of hot water too fast during peak times, leading to complaints. Also, the system will run almost constantly to maintain as much heat as possible. Such overworking causes excess wear, hot water delays, and premature failure.

That being said, “bigger is better” is not necessarily the case with water heaters. An oversized system may not be as disruptive and hold water temperatures steadier for longer. However, a larger tank can also waste energy by heating more water than is necessary. Because the system has excess hot water, it experiences more significant standby heat loss than smaller or appropriately sized systems.

3. Incoming Water Temperature

How long it takes a water heater to heat up depends in part on the incoming water temperature. Municipal supply lines travel underground to your property. The location of these municipal lines affects the temperature of the water entering your buildings. While the supply typically maintains a stable temperature throughout the year, it is significantly lower than what people want their hot water to be.

If the water heater is not an adequate size for the property or unit, more cold municipal water gets fed directly into the system during peak use times. The more municipal water is added to the system, the longer it takes to heat.

4. Desired Water Temperature

The higher the desired water temperature, the longer it takes to heat. OSHA recommends a hot water temperature of 122°F to prevent bacterial growth and spread. Many experts suggest a temperature of 120°F for safety and energy-consciousness.

Despite these recommendations, most water heaters have a factory setting of 140°F. The higher temperature not only requires a longer heating time but also increases the risk of scalding in older tenants and young children.

Some property owners deliberately keep temperature settings high to reduce heat loss throughout the plumbing supply system. If you worry about heat loss, consider installing adequate insulation throughout the property, specifically on hot water supply routes.

5. System Efficiency and Maintenance

The condition of the system also affects how long it takes a water heater to heat up. An efficient and well-maintained system will heat water faster and maintain the desired temperature for longer with less energy expenditure.

A poorly maintained system can have many issues that prolong or impair heating times altogether. The primary issue we see in these systems is sediment buildup. Sediment acts as an insulator and reduces efficient heat transfer between the heating element or burner and the water. It forces the water heater to work harder and for longer to reach a desired temperature setting.

Without regular maintenance, a water heater and its components may experience premature wear. Heating elements can degrade. Burners may become clogged and less effective. Corrosion may set in, affecting the tank’s heat exchangers and reducing the system’s overall lifespan.