Heat Pump Water Heater

Heat Pump Water Heater Performance Results

So just how effective is a heat pump water heater at providing piping hot water for an entire household?

The performance results on this page hold the answer, because they measure the electricity consumption of heat pump water heaters installed in homes worldwide, as well as the power usage of the backup electric heating element (if applicable) that turns on during periods of high demand or as an anti-legionella measure.

Air-water heat pumps are without a doubt more efficient than conventional water heaters at delivering hot water but the question has long been how they stack up when compared to solar water heaters. The information here provides real insight into that debate.

The measurements are done by the homeowners themselves using energy monitors and smart meters, which they have been kind enough to share with me to make a difference for the environment.

Results obtained in a laboratory can only take you so far because each installation has its own unique set of circumstances, so in the field measurements provide a valuable yardstick on what to really expect from a water heating system performance wise.

If you own a heat pump water heater, please consider measuring its efficiency and submitting your results here.

Heat Pump Water Heater Performance Tables

Insolation: 5.08 kW/m2 per day

Performance Indicator: Electricity Used (kwh)

Tank Size: 300 l (79 gal.)

Configuration: Integrated

Hot Water Users: Family of 4

Water Consumption: Early Morning, Medium

This heat pump water heater was installed in 2007 to provide hot water for a household of 4 people.

Measurements were taken using a dedicated kwh meter from April 2007 and a concluding reading was taken in August 2010 to be able to determine the average electricity consumption over a three year period.

The results are very impressive especially considering the length of time over which the measurements were obtained. More details here...

KVA Control - Stiebel Eltron WWK300AH

Insolation: 2.64 kW/m2 per day

Performance Indicator: Electricity Used (kwh)

Owner Name: Wilfried Groot Zevert

Tank Size: 300 l (79 gal.)

Configuration: Add-on system

Hot Water Users: Two Adults & Two Children

Live web readings are like gold dust when it comes to field performance measurements and these results are no exception.

Connected in August 2010, the data is wirelessly sent to a server twice a day and displayed on the website.

There is a wealth of information available which highlights how well the system is performing in real-time...

Live performance results

Insolation: 2.98 kW/m2 per day

Performance Indicator: Electricity Used (kwh)

Owner Name: Wouter Degraeve

Tank Size: 300 l (79 gal.)

Configuration: Add-on system

Hot Water Users: Two Adults & One Child

You would expect the performance of an air-water heat pump in Belgium to be pretty inefficient due to the low insolation rates and climatic conditions.

Well, as the saying goes, the proof of the pudding is in the eating and these performance figures that are displayed on the web in real time give the answer.

In fact, there is so much information available that it can be a little confusing, but the most important metric to look at is the electricity used...

Real-time efficiency results

Making Sense of the Results

In each table you will see information that will make the results more meaningful to you so here is an explanation of each category...

    star System Brand Name and Installer - The domestic electric heat pump water heater industry is still in its infancy so brand and installer names are important measures of performance. Click on the relevant links to find out more about the installing company and the cost of that particular system.

    star Location - Heat pump water heaters work by using electricity to move heat from one place, such as the air warmed by the sun, to another, such as water contained in a tank. So theoretically their performance should improve in warmer climates as there is more hot air to work with.

    star Tank Size - A big advantage when installing a system like this is that it can be used in conjunction with your existing tank so there is no need to buy a new one. Match the tank sizes here with your own to estimate how much it would cost to heat in your situation.

    star Installation Date - The length of time that a unit has been installed can give an indication of its reliability and also how it performs as it ages.

    star Measurement Device - It's useful to know which energy monitoring device was used to measure the electrical consumption of the air to water heat pump because some are more accurate than others.

    star Configuration - Integrated systems come in a single package while add-on systems use the existing water heater and are often placed some distance away from the tank.

    star Water Consumption - How much hot water you and your family use, and when, effects performance in a big way. So the scale below is used to roughly calculate water use. Match according to your situation, when you predominantly shower or bath such as early morning, day, or evening (If you bath rather than shower assume medium consumption):

    Low Medium High
    Shower time per person averages less than 10 min Shower time per person averages from 10 - 14 min Shower time per person averages more than 14 min

The Top Three Systems

Find out which systems rank the highest on the hot water heat pump top three list in several countries worldwide including South Africa and read some of the reviews written by people who own them.

About Solar Water Performance

This website attempts to set benchmarks for the performance of installed solar water heaters and geysers using the collective measurements of homeowners worldwide.... View More

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