Heat pump hot water service vs. standard electric storage hot water service

Sep 1, 2020

Here is some basic information when considering replacing your old electric storage HWS:

Hot water accounts for approximately 25% of your electricity bill. For a household that uses 200L/day that could be as much as $850* a year for an off peak electric hot water service

Is it possible that you could save hundreds of dollars a year by installing a hot water service heat pump?

Let’s see how this is possible

A standard electric hot water service uses a heating element to heat the water. The heating element is usually rated at 3.6Kw.  The Coefficient of  Performance (CoP) or the amount of electricity consumed to yield a given amount of heat energy for a standard electric hot water service is 1:1 that is to say it takes one Kw of electricity to produce one Kw of heat energy. In the case of the a 3.6Kw heating element it uses 3.6Kw of electrical energy to produce 3.6kw of heat energy making the element 100% efficient.

This not the same for a domestic hot water heat pump. If we look at a heat pump with a  CoP(winter) of  1:3.5 that is to say it takes one Kw of electricity and produces 3.5Kw of heat energy. We can say that the heat pump is 3.5 times more efficient at producing hot water or it operates at 350% efficiency compared to the standard electric hot water service.

Putting a dollar value on the efficiency of the heat pump is simple. If we look at the yearly bill of $850 for an electric hot water system and divide it by 3.5 being the CoP of the heat pump the cost would be $242 compared to the $850 a saving of $607.  This is a no brainer.

Keep in mind that there are some heat pumps out there that are just not up to the task and any heat pump that has a heating element that kicks in when the air temperature starts to fall is not a true heat pump.