Tankless Electric Water Heater: Flow Rate!

If you are looking for ventless tankless water heaters, then tankless electric water heater is the answer. This type is more popular with its tankless design and relatively safer. As the name suggests, it does not need a storage tank to hold the amount of heated-water temporarily and uses the electric energy as the power supply. So the unit will only heat the water as soon as we need it, this means the system will produce the mount of hot water instantly (instantaneous performance). Although it is relative easier for the installation (doesn’t need venting system) but the cost of operation is slightly higher than the same type that is powered by gas fuels. And one of crucial issues to take into consideration if you want to use this kind of heater is about flow rate!

Once again, instantaneous tankless electric water heaters are still better for cost saving if compared to the traditional units with storage-tank (typically around 80 gallons to 20 gallon), especially for residential use. They have already been popular in Europe (particularly in Greece, Sweden, Finland, Netherlands, Belgium, & United Kingdom (UK)) and North America (USA and Canada). However there are some important crucial technical points to consider on choosing and installing this type. Some of these issues are flow rate, temperature control, the mechanism of installation, long-term energy savings and service life! Let’s focus to one of those technical issues that is; “Flow Rate”!

Hot water flow rate is closely associated to the performance of the unit to produce and supply the hot water. The sum of each flow rate of all fixtures (such as clothes, dishwashers, sink, showers, and so on) should be equivalent to the hot water demand on a water heating unit.  If the maximum flow rate of the unit is lower than this sum then the unit will not be able to work powerful enough to gratify the instantaneously demand from all fixtures. And the temperature generated is usually not equivalent to the flow rate. Therefore, the lower flow rate tends to produce the higher temperature of hot water, and on the other hand, the unit that has higher flow rate usually will produce the lower generated-water temperature.

The unit will supply and produce hot water only up to its highest rated flow rate. And if this level is exceeded, the water will be pushed to the outside of the unit before it gets the desired temperature. You may find some brands that claim their tankless products will be able to supply the instantaneously unlimited hot water! But in fact, this statement is too difficult to be realized and only can be realistic if the unit is installed in the right settings where it would only have to be used for 1 or 2 uses of simultaneously hot water.

Generally, the maximum flow rate of tankless electric water heaters are usually around 4 GPM (Gallons per minute). This size is less powerful if compared to the maximum flow rate of gas tankless units that can be up to 6-7 GPM! Therefore, electric models usually will not be powerful enough for a large family because they are usually only able to supply 1 shower or 2 showers or 2 dishwashers simultaneously. So you may need to install more than one unit to meet your family’s demand.

In addition, either electric or gas tankless water heaters are usually designed with a threshold level of minimum flow rate. This feature will make the unit be not-active if the level reaches lower than the threshold. And this threshold is controlled by flow detection mechanism that usually each brand or manufacture has their own flow detection design. Example, if you have a faucet that has 0.6 minimum flow rate and your tankless unit has 0.8 minimum of flow-rate then there is no hot water that supplied and distributed to the faucet.

Image source: Amazon.Com

Read also how to calculate the size of pool heaters?

More tags: