Whenever you turn on the tap and set it to red, two things happen. First, your hot water tank springs into action. It either warms up the needed water, or delivers pre-heated water from a holding tank. Next, the water travels through the home’s plumbing and into the open tap.
As you can imagine, the farther away the hot water source is, the longer it takes for the water to turn hot at the end destination.
A point-of-use water heater seeks to shorten the waiting time.
What is a Point of Use Water Heater?
A point of use water heater is a small unit that heats the water close to where it’s needed, whether it’s a faucet, shower, tub, kitchen sink, or washing machine.
This is why such heaters are known by several names, including “point of service water heater”, “on demand POU water heater”, or simply POU or POS water heater.
POU water heaters are compact enough to be installed under most sinks and can be integrated to the existing plumbing system. Compared to central water heaters or hot water recirculation systems, this makes them a popular option for homeowners on a budget, have limited space, or have few outlets that need hot water.
Types of Point of Use Water Heaters
There are two main types of POU water heaters: tank and tankless.
1. Point-of-use tank water heater
These look like a miniaturized version of the traditional tank water heater. Their smaller size allows them to be installed close to typical water outlets, such as undersinks. POU tank heaters range from 2.5 gallons to 20 gallons.
2. Point-of-use tankless water heater
Like their larger tankless brothers, a POU tankless heater doesn’t store heated water. It only gets to work once a tap is opened. This allows it to have a smaller footprint than the POU tank heater, in exchange for a slight delay in hot water delivery.
In terms of location, POU water heaters are also available in different designs:
- Under sink
- Over sink
- Wall mounted
What are the Benefits of a Point of Use Water Heater?
- According to the DOE, water heating is the second highest energy use in residential homes, second only to HVAC. In fact, it can account for nearly 20% of a typical home’s electric bill.
- The Energy Star initiative shows that even homes equipped with a central water heater can benefit from point of use water heaters, since they can help reduce the heat lost in the water distribution system. POU heaters can restore the hot water temperature in fixtures farthest from the central heater. In terms of energy efficiency, it can be advantageous compared to increasing the temperature setting of the central storage water heater.
- A POU heater may also be a better choice when heating water for a hot tub.
- DOE estimates show that homeowners can lower their monthly water heating costs by as much as 50% by using POU water heaters at each water outlet.
- This translates to a minimum savings of $100 annually when using a POU water heater.
- Most tank water heaters typically have a 10-15 year life expectancy, based on data from the DOE.
- In contrast, tankless water heaters can last for up to 25 years given proper maintenance.
- In addition, once they finally reach end of life, tankless POU heaters are much easier to replace compared to bulky central storage tank units.
When Does a POU Water Heater Make Sense?
POU heaters are the ideal choice in the following cases:
Smaller homes with limited fixtures
It makes better sense to have point of use heaters in homes with only one bathroom and a limited amount of hot water outlets, such as a kitchen sink and washing machine.
Larger homes with distant water outlets
For large residences, heat loss can be an issue. Older or uninsulated plumbing can reduce hot water temperature by up to 5°F. Even with well-insulated pipes, the farther the water has to travel from the central heating tank, the cooler it gets when it reaches its intended destination. A POU heater can boost the temperature at the endpoint without having to raise the temperature of the storage tank itself.
Infrequent hot water use
Homes with less hot water demand can save a lot by using POU heaters, instead of relying on a wasteful storage tank heater that keeps water heated even though it’s infrequently needed.
POU heaters excel in water outlets that are rarely used, such as guestrooms or powder rooms.
Homes with limited space or plumbing issues
Because of its compact nature, POU heaters can easily fit under most sinks, especially the tankless models. They can also be installed right into the existing pipe with a minimum of fuss, making them the ideal solution without having to redo the whole plumbing system.
How to Choose a POU Water Heater
Step 1: Determine your hot water consumption
Before checking out specific models and reviews, you need to know how much hot water you use for a given water fixture.
Here is the average supply requirement for most water outlets:
|Flow rate (gallons per minute)||Minimum pressure required (psi)|
Kitchen sink ⅜-½”
Kitchen sink ¾”
Step 2: Determine the type you need
With water consumption in hand, you can now choose between tank and tankless POU water heaters.
The flow rate is the amount of hot water the heater can deliver per minute. Most tankless POU heaters have a flow rate of 0.35 to 0.5 gpm, while mini-tank POU water heaters can hold 2.5 gallons. Larger tank POU heaters can hold up between 4 to 7 gallons.
Step 3: Determine the size
If you decide to go the tank route, you need to determine the tank size and recovery rate.
Tank size – how much hot water the tank can hold at any given time
Recovery rate – the less time it takes to heat the water, the shorter your waiting time will be. This is determined by the efficiency and wattage of the unit’s heating element. In general, higher watts means shorter recovery time.
The Best Point of Use Water Heaters for 2021
Budget tankless POU water heater:
Measuring just 14×10 inches, this compact water heater is small enough to fit in tight spaces while its low price tag can fit the tightest budget.
The EMT1 includes an adjustable thermostat to control the temperature, and an indicator light to let you know when water is being heated.
Premium tankless POU water heater:
This 2-gallon water heater has a 90°F recovery rise of about 7 minutes, and boasts an ETL rating for HUD Mobile Home Construction and Safety Standards for Energy Efficiency.
Like other Bradford White heaters, it comes with fully automatic controls and the brand’s Vitraglas® Lining enamel layer, which protects the unit from the corrosive effects of hot water for a longer lifespan.
Mini-tank POU water heater:
This mini-tank POU heater can store up to 6 gallons, enough to service a dishwasher load or 5-minute hot shower. At less than 17” tall, it’s also compact enough to fit in tight spaces. Like the rest of Bradford White’s heater line, it boasts fully automatic controls and Vitraglas enamel lining for exceptional corrosion resistance.
In fact, our test results show that Vitraglas provides unsurpassed protection against failure compared to other water heater linings.
Larger-capacity tank POU water heater:
This 19-gallon POU heater combines the storage capacity of conventional tank water heaters with the compact size and energy efficiency of point-of-use heaters. This makes it the ideal choice for situations where hot water demand is intermittent but space is at a premium, such as small boats, RVs, or wet bars.
As with other Bradford White heaters, it comes with fully automatic controls, Vitraglas enamel lining, and ETL HUD Mobile Home Construction and Safety Standards for Energy Efficiency certification.