Point of use tankless water heaters are powered by electricity and can serve up to two water fixtures
The reason they are called point-of-use tankless water heaters is because they need to be installed in close proximity to the tap they will serve. Due to the short distance the heated water has to travel, hot water is practically delivered instantaneously. This is the very reason why point-of-use tankless water heaters are often referred to as instantaneous water heaters.
Point-of-use water heaters are also used by traditional water heater owners to lessen the hot water delay due to long pipes runs. This makes them very useful for remote areas of the home that are far away from where the hot water storage tank is located. In fact, you don’t even need to run any pipes from the storage tank water heating unit going through the remote bathroom as the point-of-use tankless water heating unit can well enough supply your water heating needs on that specific bathroom. Doing this can save you money on plumbing and installation costs on new constructions.
Due to their compact size and since they do not require any venting systems, these small electric-powered tankless water heating units can be installed inside cabinets or under the sink to provide hot water for the kitchen sink, shower, and bathroom sink. In addition, since they are tankless models, they are able to supply you with endless supply of hot water.
There are higher capacity point-of-use tankless units that are able to serve two taps at the same time – that being the shower and the bathroom sink. However, most models are low capacity and are able to serve only the tap in which they are installed. If you will be purchasing a point-of-use tankless water heating unit, it is advisable to choose a unit that can handle your required temperature rise on the area where you live.
The truth is point-of-use water heaters are not necessarily tankless as there are mini-tank water heater models. These water heating units are powered by electricity and have 2.5, 4, and 6 gallon capacities which is why they can also be installed in close proximity to the hot water tap you will be using it on. Their small tank capacities allow you to install them under sinks. Their main drawback though is that they are not able to supply you with unlimited amounts of hot water like tankless models do.
Point-of-use water heaters are mostly installed for three reasons: first, it can be used to provide hot water for remote taps or taps that are not connected to the main water heater or if there is no main water heater; second, it can be used to remove the long delay spent from long pipe runs from the main water heater; and lastly third, it can be installed as an inline water heating system to elevate the temperature coming from the main water heater. If you choose to install point-of-use water heating units on a new home construction on areas that may use hot water, you may actually save money on plumbing and material costs. Regardless of your reason for installing a point-of-use unit, the main objective is that you get hot water whenever you need it.
A point-of-use tankless water heating unit is cheaper to buy and install and can provide you with endless amounts of hot water. Since they are tankless models, they are more efficient as they are not subjected to standby heat loss like tank models are. In addition to this, they also have a much longer warranty than other water heater types. While point-of-use mini-tank cost lesser, the limited hot water it can provide can sometimes be a drawback.
Most point-of-use water heaters have very low flow rate which is why they can only be used on one tap. However, there are also models that have a higher flow rate which is why they can be installed and used on two taps running simultaneously.
Some point-of-use tankless water heating units, particularly those installed under the sink require a minimum flow rate in order for the unit to turn on automatically. If the minimum flow rate is not met, the flow rate sensor of the water heating unit will not initiate the heating process even if the faucet is turned on. Most under-the-sink tankless water heating units will have a minimum flow rate of 0.5 to 0.75 GPM (Gallons Per Minute).
One of the highly rated point-of-use water heating units that can be installed under the sink are the Bosch PowerStar models. All Bosch PowerStar models require 240 volt wiring. The PowerStar AE3.4 is small enough to run on a 15 ampere circuit, while other PowerStar models such as the AE12, AE115, and AE125 needs a 200 ampere electrical service.
The Bosch PowerStar AE3.4 is able to serve one bathroom sink for areas with warm climates only. The Bosch PowerStar AE7.2, AE9.5, AE12 on the other hand are able to serve one bathroom sink regardless of climate. The Bosch PowerStar AE115 has enough flow rate to supply 1 shower and 1 bathroom sink, or 2 bathroom sinks in areas with warm climates only. The Bosch PowerStar AE125 on the other hand is able to serve 1 shower and 1 bathroom sink, or 2 bathroom sinks simultaneously regardless of climate conditions.
There are other high quality point-of-use tankless water heating models such as the Titan SCR2, Stiebel Eltron’s Tempra and DHC series, and models made by Chronomite, Eemax, and Seisco.
If you need a point-of-use mini-tank model, then you should look into Bosch Ariston, Eemax, Insinkerator, Rheem, and Stiebel Eltron. Mini-tank water heaters are compact in size and come in 2.5, 4, and 6 gallon capacities. The tanks are well insulated to further reduce standby heat loss. Many models are equipped with glass linings as well as sacrificial anode rods to reduce corrosion towards the tank. Mini tanks can be plugged in on standard 110-120 voltage outlets with no special wiring needed. However, there are some 6-gallon models that needs to be hard-wired towards the electrical system with a 10 ampere current draw.