Tag: Water Heaters

Types of Commercial Water Heaters: Feel the Heat this Valentine’s Day

Posted on by 360 Engineering

When it comes to commercial water heaters, building owners and tenants have several options to choose from, each with its own set of advantages and disadvantages. As plumbing engineers, we know that understanding these options is crucial for recommending the best solutions to our clients. In this blog post, we’ll explore the different types of commercial water heaters, including electric resistance, heat pump, gas-fired, and the differences between tankless and storage tank types. We’ll also touch on the Denver Energy Code changes and restrictions related to service water heating. Our goal is to help everyone “feel the heat” this Valentine’s Day!

Electric Resistance Water Heaters

Electric resistance water heaters are commonly used in many settings, especially for tenant spaces with relatively small fixture hot water loads or in areas without natural gas or propane readily available. They work by using electric resistance heating elements to conduct heat to the water stored in a tank. These heaters are relatively simple to install and maintain, making them a popular choice for many owners.

Pros:

  • Easy to install and maintain
  • Widely available
  • Can be installed in various locations (no venting to the exterior required)

Cons:

  • Slower recovery rate compared to gas-fired water heaters
  • Higher operating costs compared to gas-fired or heat pump water heaters

Heat Pump Water Heaters

Heat pump water heaters are an energy-efficient alternative to traditional electric resistance heaters. They work by transferring heat from the surrounding air to the water, using a refrigeration cycle. This process makes them significantly more efficient, as they use less electricity to heat the same amount of water—it’s generally more efficient to move energy from one medium to another rather than “create” it by burning gas or heating up resistor.

Pros:

  • Highly energy-efficient
  • Lower operating costs
  • Environmentally friendly

Cons:

  • Performance can be affected by ambient temperature
  • Higher upfront cost
  • Requires a well-ventilated space, or potentially outdoor space for the condenser
  • For split systems with outdoor condensers, requires water piping to run outside—which creates additional design requirements for freeze protection

Gas-Fired Water Heaters

Gas-fired water heaters use natural gas or propane to heat the water. They are known for their fast recovery rates and lower operating costs compared to electric resistance heaters (until electricity and gas prices start to coincide). These heaters are a popular choice in areas where natural gas is readily available.

Pros:

  • Lower operating costs
  • Faster recovery rate
  • Reliable performance

Cons:

  • Potential for gas leaks
  • Requires a gas line and proper ventilation (both combustion air intake and flue exhaust to the outside)
  • Higher installation costs

Tankless vs. Storage Tank Water Heaters

Another significant decision to face is choosing between tankless and storage tank water heaters. Each type has its own set of benefits and drawbacks.

Storage Tank Water Heaters

These are the traditional water heaters with a large tank that stores hot water until it’s needed. They are available in various sizes, typically ranging from 10 to 120 gallons (though both larger and smaller options exist as well).

Pros:

  • Lower upfront cost
  • Simple and reliable
  • Can provide hot water to a large quantity of fixtures simultaneously

Cons:

  • Higher energy consumption due to standby heat loss
  • Takes up more space
  • Limited hot water supply, depending on the provided recovery rate (higher recovery rate equals higher energy usage)

Tankless Water Heaters

Tankless water heaters, also known as on-demand or “instantaneous” water heaters, heat water only when it’s needed. They do not store hot water, which eliminates standby heat loss.

Pros:

  • Energy-efficient
  • Endless hot water supply
  • Compact size

Cons:

  • Limited flow rate (the higher than required instantaneous hot water flow, the greater the energy required)
  • Higher upfront cost
  • May require upgrades to electrical or gas systems

Denver Energy Code Restrictions

The Denver Energy Code has specific restrictions on the types of water heaters that can be installed in new and existing commercial buildings. As of March 1, 2023, the code requires partial electrification for all existing commercial and multifamily buildings when replacing gas-fired space and water heating equipment1. This means that gas-fired water heaters are being phased out in favor of more energy-efficient options like electric heat pump water heaters2.

For commercial buildings, the Denver Energy Code also encourages the use of electric heat pump water heaters and restricts the installation of new gas-fired water heaters3. These changes are part of Denver’s broader efforts to reduce carbon emissions and promote sustainable building practices.

Valentine’s Day Jokes

And because you asked for it, here are some Valentine-themed jokes to help everyone feel the heat (or maybe just make us plumbing engineers chuckle):

  • What did the tankless water heater say to its Valentine? “With you, I never run out of love!”
  • Why did the electric water heater break up with its partner? It just couldn’t handle the constant resistance!
  • What did the water heater say to its crush on Valentine’s Day? “You make me feel like my T&P valve is about to go off!”

Conclusion

Choosing the right water heater for a commercial building involves considering various factors, including energy efficiency, operating costs, and installation requirements. Electric resistance, heat pump, gas-fired, storage, and tankless water heaters each have their own advantages and disadvantages. Understanding these options and the local energy code restrictions can help businesses make informed decisions.

Whether you’re a business owner, plumber, or engineer, understanding the intricacies of water heaters is key to ensuring a comfortable working environment—just like keeping the warmth alive in your Valentine’s heart!

1: Building Code Changes for Existing Buildings – City and County of Denver – https://www.denvergov.org/Government/Agencies-Departments-Offices/Agencies-Departments-Offices-Directory/Climate-Action-Sustainability-and-Resiliency/Cutting-Denvers-Carbon-Pollution/Efficient-Commercial-Buildings/Denver-Building-Regulations/Denver-Energy-Code-for-Existing-Buildings/Building-Code-Changes-for-Existing-Buildings

2: 2022 Denver Energy Code Fact Sheet Electrification for Service Water Heating – https://www.denvergov.org/files/assets/public/v/1/climate-action/documents/hpbh/nze/2022-denver-energy-code-fact-sheets-c-electrification-for-service-water-heating.pdf

3: Denver Energy Code Requirements for Existing Buildings – https://www.denvergov.org/Government/Agencies-Departments-Offices/Agencies-Departments-Offices-Directory/Climate-Action-Sustainability-and-Resiliency/Cutting-Denvers-Carbon-Pollution/Efficient-Commercial-Buildings/Denver-Building-Regulations/Denver-Energy-Code-for-Existing-Buildings

Hot Water Decoded: An Introductory Guide to Water Heaters

Posted on by 360 Engineering

As the name suggests, water heaters are equipment that will raise water temperature. Water heaters come in many shapes and sizes but can be characterized by storage and energy sources. Storage methods are tank or tankless; the energy source is electricity or fossil fuels. Tank water heaters, also called “storage” type water heaters, hold a set volume of water that is heated through prolonged contact with the internal heating components. Tankless, or “instant,” water heaters use a much higher energy input to heat the water to the desired temperature as it flows to the fixture.

There are two main ways to use electricity to heat water, one being electric resistance and the other by using the electricity to run a heat-pump refrigerant cycle. Electric resistance-style heating elements are simple and have no moving parts, but the energy output is equal to the energy consumed by the coil. Although heat-pump water heaters also use electricity to operate, they “move” heat instead of “creating” it. This process is a more efficient way of heating water, allowing heat pump water heaters to be up to 410% more efficient than an equivalent resistance style.

Components of a Heat Pump Water Heater

Water heaters that use fossil fuels as the energy source are usually referred to as gas water heaters. The options for source types are most commonly natural gas or propane. Natural gas is the fossil fuel utility most often offered by service providers, while propane is usually shipped and stored in tanks on-site. Although most gas water heaters are similar, the most noticeable difference is between condensing and non-condensing style burners.

When gas-fired equipment burns fuel, it doesn’t use 100% of the energy released from combustion, resulting in a mixture of unburnt fuel and water vapor. If cooled enough, the flue gases can condense on the flue vent piping, leading to corrosion. Hence, manufacturers reserve approximately 20% of the energy released to keep the flue gas temperatures high enough to prevent condensation. More modern gas-fired water heaters will utilize the condensation to put more energy into the water instead of keeping the flue vent gases hot, resulting in efficiencies up to 98%. The corrosive condensate produced by this process is handled by using resilient metals for the heat exchanger and acid-neutralization kits to ensure the condensation produced is safe for sanitary lines and treatment plants.

Condensing vs. Non-Condensing Continuous Flow
Tank-Type Water Heaters
Pros
  • Lower instant power consumption to satisfy the hot water demand
  • Fewer components
  • Less expensive to purchase and maintain
Cons
  • Larger footprint
  • Heavy when filled
  • Thermal energy loss over time
  • Less flexible installation options
Tankless Water Heaters
Pros
  • Smaller footprint
  • When sized correctly, provides the user with a constant supply of heated water all year round
  • Less heat loss
Cons
  • Larger energy input
  • Contains more complicated controls and safeties
  • More expensive to purchase
Electric Resistance Water Heaters
Pros
  • Ease of installation (no flues required)
  • Simple/reliable operation
Cons
  • Can require electrical service upsizing
  • Power input depends on voltage availability
Heat Pump Water Heaters
Pros
  • Highest efficiency
  • Provides cooling in the summer by extracting heat from the room
Cons
  • New technology
  • Highest equipment first cost
  • More maintenance
  • Takes energy away from the room, requiring the heating system to compensate in the winter
Gas-Fired Water Heaters
Pros
  • Higher energy density of fossil fuels means smaller pipes are required
  • Provides large volumes of heated water independent from what electrical service is available
Cons
  • Requires combustion air to operate
  • Requires flue vent piping
  • Products of combustion are released near the building, lowering the air quality of the surrounding area