Electricity Saving Tips For Homes And Offices

Heat Pump Water Heaters: What are they? How they help in saving electricity?

By on April 22, 2016

Life in today’s world is becoming more and more challenging. And at the same time it is becoming more and more easier than it was a few decades ago. Human comfort depends on many different things. In order to cater to the myriad of human needs, there are a variety of appliances which offer the needed services just at the flick of a button.

Water heaters have become a household thing since long. Earlier people used some rudimentary methods to heat the water which they required for some specific needs, but with the advent of technology science has brought many feasible options to us which would cater to the same needs in a more efficient way. Heat Pump Water Heaters do just the same.

What are Heat Pump Water Heaters?

Before we go on to see the various benefits it offers, it is very important to first understand what are Heat Pump Water Heaters.

There are basically two types of water heaters

  1. Instant water heaters (electric and gas)
  2. Storage water heaters (electric and solar)

We have discussed in detail about these in our article “Water Heater: Choose the right one for your needs”.

How do Heat Pump Water Heaters work?

Water Heaters with Heat Pumps are a tremendous option to conserve electricity and reduce the money spent on electricity bills. As a refrigerator cools things kept in it by taking the heat from them and venting it outside, a heat pump works in just the opposite way. That is, it takes the heat from the surroundings and uses it to heat the water. It also has a refrigerant gas like an air conditioner has, which flows in the pipes connecting the different internal components of a heat pump water heater.

These water heaters absorb the heat in the air and transfers it to the water in the storage, thus increasing the temperature of the water and releasing cool air outside. That is why one experiences coolness around these type of water heaters. In fact, it can actually be used for cooling the air too. Water Heaters with Heat Pumps not only heat the water, but they do so very efficiently and very quickly. This is because in addition to the electricity they consume, they also take the heat from the air to heat the water.

(Source: http://www.mncee.org/getattachment/Innovation-Exchange/Projects/Current/Heat-Pump-Water-Heaters--Savings-Potential-in-Minn/heat-pump-diagram-(1).png.aspx)

Working of a Heat Pump Water Heater (Source: http://www.mncee.org/getattachment/Innovation-Exchange/Projects/Current/Heat-Pump-Water-Heaters–Savings-Potential-in-Minn/heat-pump-diagram-(1).png.aspx)

Energy efficiency of Heat Pump Water Heaters

Heat Pump Water Heaters are the best option one has if one wants to save electricity. This is because its efficiency is increased as in addition to consuming electricity, it also takes up heat from the surroundings to heat the water up. So it means that the same amount of water will be heated up in lesser time than in a regular water heater, as total energy consumed is more in case of Heat Pump Water Heaters. How?

If a regular water heater consumes 1 kW to heat up a given quantity of water, a heat pump water heater, in addition to the 1 kW takes up heat from the surroundings amounting to 2.5 kW on the same 1 kW electricity consumed on an average. This means that on the same 1 kW electricity being consumed, a heat pump water heater provides 3.5 kW output (1 kW + 2.5 kW) to heat the same quantity of water. Please not that this value (2.5 kW) may vary according to the brand or specifications of the product you are buying. It can be lower than 2.5 kW and it can be higher than 2.5 kW as well. It entirely depends on the heater that you are buying. So it is advised that you go through the specifications of the product in detail before buying.

How does it affect my savings on electricity?

Let us come down to the part which concerns your expenses on the electricity consumed. The minimum capacity of a heat pump water heater that is readily available (brands like AO Smith, Racold, Bajaj)  in market now-a-days is 50 litres. So let us assume the quantity of water you want to heat is 50 L. Here we consider the two water heaters, a regular water heater and a heat pump water heater.

As we discussed in one of our articles “Choose the right sized water heater/geyser for electricity saving”, the total number of electricity units consumed can be found out using a basic formula-

Ideal Units for heating = Volume of Water x Temperature Difference x 0.0012

Here the volume of water is 50 L. Let us assume that the temperature of the tap water is 20 oC and you want to use it at 60 oC. So the temp difference is 40 oC (60-20).

Regular water heater Heat pump water heater
Number of electricity Units consumed = 50 x 40 x 0.0012 = 2.4 units Number of electricity Units consumed = (50 x 40 x 0.0012) / 3.5 = 0.69 units

So this means that where a regular water heater uses 2.4 units of electricity, a heat pump water heater uses 0.69 units. And how does it affect your expenses?

Let us assume the tariff is Rs 5 per unit.

Expenditure on 1 unit = Rs 5 Expenditure on 1 unit = Rs 5
Expenditure on 2.4 units = 5 x 2.4 = Rs 12 Expenditure on 0.69 unit = 5 x 0.69 = Rs 3.45

Suppose the water heater is used for 30 days

Regular water heater Heat pump water heater
Total number of units in 30 days = 2.4 x 30 = 72 Total number of units in 30 days = 0.69 x 30 = 20.7
Expenditure on 72 units = 5 x 72 = Rs 360 Expenditure on 20.7 units = 5 x 20.7 = Rs 103.5

The prices of a regular water heater and a heat pump water heater will be different. Usually the price range of a regular water heater is in the range of Rs 10000- Rs 15000 and that of a heat pump water heater lies in the range of Rs 17000 – Rs 25000.

So let us assume the price of a regular water heater is Rs 13000 and that of a heat pump water heater is Rs 20000.

Then the difference in the cost of buying = 20000 – 13000 = Rs 7000

In a month (30 days) you are spending Rs 103.5 if you use a heat pump water heater and Rs 360 if you use regular water heater. So the savings = Rs 360 – Rs 103.5 = Rs 256.5

So how long will it take to recover Rs 7000?

(7000/256.5) = 27 months = 2.25 years (approximately)

It means that if you buy a heat pump water heater (which is costlier than a regular water heater of the same capacity) then in almost 2 years and a quarter, you will be able to recover the extra money you spent on buying the heat pump water heater. And after that, it will all be savings on electricity !

Benefits of using Heat Pump Water Heaters

Heat Pump Water Heaters provide a very suitable and efficient alternative to the regular water heater. Here are a few benefits of using Heat Pump Water Heaters-

  1. It can heat up large volume of water at a time. They come in different varieties having capacities upto 200 Litres (or more sometimes).
  2. These are highly cost effective as they consume lesser electricity to heat up the same volume of water than a regular water heater.
  3. They do provide service for a long time. Meaning? They have a long life.
  4. They can act as coolers as well as they tend to cool up the place where they are installed.
  5. Heat Pump Water Heaters are absolutely safe.
  6. The installation requires little effort. Also they are easy to maintain.

Drawback

Since a heat pump water heater contains a refrigerant gas, it is important that the heating coils are protected against corrosion. Also since the refrigerant gas might not be environment friendly, so it is advised that it should be properly checked for its ill-effects on the environment.

Conclusion

Heat Pump Water Heaters are a tremendous innovation in the field of appliances, especially the ones which are light on the electricity consumption. So if you want to spend lesser than what you pay currently for using warmer water, heat pump water heater is the thing which you would not want to miss out on.

References:

http://energy.gov/energysaver/articles/heat-pump-water-heaters

https://www.energystar.gov/index.cfm?c=heat_pump.pr_how_it_works

https://www.energystar.gov/index.cfm?c=heat_pump.pr_savings_benefits

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