In using a tankless hot water heater, you can have hot water whenever you need it. These systems instantly heat water as it flows through the device and does not retain any water internally except for what is in the heat exchanger coil, making these heaters highly efficient and safe. With today’s technology, an endless supply of hot water is available when needed.
Unlike standard units, which continuously heat and reheat water so that it is always hot, tankless heaters generate hot water instantly using high-powered gas burners or electric coils. Yes, this instant heating requires more power, but because the water does not have to be reheated again and again, like in a standard ‘tank model,’ tankless systems use less energy overall.
Pros and Cons of Compact Water Systems
Does the system really provide ‘instant hot water’ at a uniform temperature?
Pro: After running (wasting) the cold water from the pipes out of the faucet, tankless water heaters can provide an unending stream of hot water almost instantly.
Con: Inconsistent water temperatures due to the heater’s inability to send enough hot water to multiple outlets simultaneously. It has also been noted that the faucets must be opened fully to activate the heater.
What is the expected life of a tankless hot water heater?
Pro: Most tank heaters have a life expectancy of ten years, whereas tankless models function for twice as long.
Con: A longer lifespan equates to a more expensive unit with the tankless unit costing more than twice as much. They are also more expensive to install, so labor fees must be factored into the overall price tag.
Pro: While these systems are more expensive, they are also more efficient. In fact, Consumer Reports indicates that tankless water heaters are 22% more efficient than standard models. The monthly savings might be nominal, but homeowners can expect to save hundreds of dollars annually.
Con: Tankless water heaters supply a steady stream of hot water, but the supply is not unlimited. Standard models heat several gallons of water at once – perfect for a single person taking a shower or washing the dishes. But if an individual is running the dishwasher or washing machine while someone else is taking a shower (or two people are taking showers in two different bathrooms at the same time), a tankless heater is not equipped to keep up. A traditional water heater, which can store between 30 and 80 gallons, will not have a problem providing hot water to multiple outlets at the same time.
In gas fired systems, the use of electronic ignition means no standing pilot light that constantly uses energy. When purchasing a system, use an ENERGY STAR certified tankless water heaters for additional savings.
Tankless Hot Water Heaters Have a Compact Design
Advantages and Disadvantages of Tankless Hot Water Heaters
Advantages - the main advantages of a tankless water heater system is the continuous flow of hot water as compared to the limited flow of continuously heated hot water from a conventional tank water heaters, and
Disadvantages – the main disadvantage of tankless hot water systems are their high initial costs (equipment and installation).
Operation of a Tankless Hot Water Heater
The heater is normally turned off but is equipped with flow sensors which activate it when water travels through them, and a negative feedback loop is used to bring water to the target temperature. Water circulates through a copper heat exchanger (copper heat exchangers are preferred because of their high thermal conductivity and ease of fabrication) and is warmed by gas or electrical heating.
Tankless heater controls
Tankless water heaters can be further divided into two categories according to their heating capability: "full on/full off" versus "modulated". Full on/full off units do not have a variable power output level; the unit is either fully on or completely off. This can cause an annoying and possibly hazardous variation of hot water temperature as the flow of water through the heater varies. Modulated tankless water heaters change their heat output in response to the flow rate of water running through the unit. This is usually done by using a flow sensor, a modulating gas valve, an inlet water temperature sensor, and an outlet water temperature sensor-choke valve. A properly configured modulating heater can supply the same output temperature of water at differing water flow rates within their rated capacity.
A smart investment for now and the future - increase your home’s value with a tankless hot water heater. You will obtain an improved Home Energy Rating System (HERS) Index Score and optimized LEED certification. Additionally, available energy efficiency rebates and tax credits offer the opportunity to help make your purchase more affordable.