Tankless water heaters were widely used in Europe and Japan long before they became popular in the United States. Thanks to the rise of the sustainability movement, these energy-saving appliances are now well established in the U.S. market.
According to the U.S. Department of Energy, water heating contributes to about 18% of home’s energy consumption. Installing and using the right type of water heaters can bring substantial amount of savings in annual energy cost. However, it may require you to replace an existing conventional storage-based water heater with the tankless model. Initial upgrade cost is not cheap, but you will notice the benefit in the long run. There are clear differences between storage and tankless water heaters, as explained below.
Storage Water Heaters
The most widely used water heater in the United States is the conventional storage type. The first automatic tank-type water heater was invented around 1889 by Edwin Ruud, a Norwegian mechanical engineer, after he immigrated to Pennsylvania, and it has been popular ever since. One of the best things about storage water heaters is its simplicity. This appliance is basically a tank or drum filled with water and heating mechanism at the bottom. Most tanks are made of stainless steel and glass-lined on the inner surface to prevent corrosion. A supply pipe (or dip tube) feeds cold water to the heating mechanism (either an element or a burner). As the water reaches high temperature, it rises to the top of the tank. Heat-out pipe, also located near the top of the tank, takes the water and brings it out.
For safety reasons, all storage water heaters have T&P valves, which will open when temperature and pressure inside the tank exceed safe limit. As hot water flows out of the tank, cold water enters to replace it. The tank is always full and it can store anywhere between 20 and 80 gallons at any given time. Water is constantly heated inside the tank even when hot water tap is closed. All the energy wasted by this mechanism is called standby heat loss. Tankless water heaters do not suffer from the same energy loss issue. However, newer models of storage-based models feature insulated tank to minimize wasting energy.
A storage water heater is typically designed to last at least 10 years; more advanced models can give 20 years. Periodic maintenance can extend its life and minimize energy loss. Each brand requires specific maintenance procedures, but most include:
- flushing out water from the tank every three months
- checking T&P valve every six months (replacing them if needs be)
- replacing anode rod every three years
Pros:
- Lower initial purchase price
- Periodic maintenance should be simple and you can do it without help from professional plumbers if motivated. In case replacements are necessary, use only parts recommended by the manufacturer
- Easy installation. Even when you have to hire professionals, the cost is not overly expensive
- Unless you use an electric-type, storage water heaters can deliver hot water during power outages
Cons:
- High energy consumption. Insulated tank is better, but not by much
- More capacity means bigger tank, so it takes up more space
- There will be preheat time after you use all hot water inside the tank
- When T&P valve opens, water will leak out
- Sometimes hot water flows out along with rust, especially when the tank is corroded
Tankless Water Heaters
While the storage type is still widely used, the tankless model is becoming more popular. As the name suggests, it has no storage tank so it heats water on-demand. There is no constant heating mechanism as the appliance works only when you need hot water flowing. This can mean significant energy saving, but the initial purchase price can cost up to three times more than the conventional model does. If you choose to have the electric-powered model, it is probably necessary to make electrical upgrades as well.
When you turn on the hot water tap, the cold water from the supply line enters the appliance and activates a powerful heat exchanger, which usually consists of a coil. Powered by either gas burner or electricity, the coil transfers heat directly to the water. As a result, the water that comes out of the appliance has high temperatures. Advanced models offer temperature setting, so you have control over energy usage as well.
A single tankless water heater can deliver up to 5 gallons of hot water per minute. Higher temperature means slower flow rate (the amount of heated water at one time). The biggest downside with tankless water heater is that you cannot reliably use it for multiple fixtures at the same time. For example, using hot water for the shower and dishwasher simultaneously will reduce the flow rate and pressure. You can overcome the problem by installing a large whole-house heater or multiple heaters, which will increase initial cost. A tankless water heater can last for 20 years or more with regular maintenance such as:
- De-lime procedure to remove hard water deposits
- Flushing every 6 months or so
- Regular service at least once a year
The cost for maintenance is another issue. Tankless water heater is quite sophisticated appliance, and all those maintenance procedures are best left to professionals.
Pros:
- You never run out of hot water
- Expected useful life is 5 – 10 years longer than their storage-based counterparts
- No standby heat loss
- Most tankless water heaters are small; you can install them on walls or outdoor siding
- Save up to 34% of water heating bill, depending on water usage
- Use energy to heat certain amounts of water to specific temperature only
Cons:
- Initial cost is high; the price can be up to $1,000 higher or more than conventional water heater
- Installation requires professionals
- Electrical upgrade (if necessary) can cost up to $5,000
- Some models are sensitive to hard-water, so you need water-softener as well
Tankless water heaters have been widely used in Europe and Japan long before they became popular in the United States. Thanks to the rise of the environment-friendly movement, these energy-saving appliances are now well established in the U.S. market. Brentwood Star Plumbing Company has noticed a significant increase in demand for tankless water heaters in the Nashville, TN area. We expect this rise in demand for more sustainable energy consumption to continue, and look forward to seeing more clean energy technology innovations adopted in our community.
All images courtesy of Brentwood Star Plumbing.
Todd Hodges
Brentwood Star Plumbing Company
http://www.brentwoodstarplumbing.com
brentwoodstarplumbing@gmail.com