Water-Source Heat Pumps – Are these HVAC systems worth Installing?

House and lake: ideal for water source heat pump installationImage by jimsimons from Pixabay

When looking to invest in a comfortable, reliable, durable, and cost-effective heating and cooling system, considering the type of an HVAC unit is very important. There is a wide selection of electric, gas, solar and oil-powered systems, but one is worth mentioning – heat pumps. You can choose an air source type, geothermal, or water source. This article will focus on water-source heat pumps, its benefits, and why it's worth investing.

Firstly, we need to know what to consider, advantages and disadvantages before getting a water source heat pump.

Are water source heat pumps a worthy investment?

Before anything else, let's see how water source heat pumps work? Like geothermal and air-source heat pumps, they draw heat from the surrounding (air, ground, or water), which is, in this case – water, but the method varies depending on the type of loops used. The outdoor piping can be open or closed loop.

Closed-loop system – this system uses a continuous loop of piping submerged in the water body. In the heating cycle, the antifreeze mixture or refrigerant circulates through the piping system, picks up heat, and sends it to the heat pump, installed inside the house, for heating. Once the heat is transferred, the antifreeze mixture/refrigerant circulates back to be heated again. In the cooling cycle, the process is reversed, thanks to the reversing valve. The refrigerant picks up heat from inside the house and sends it directly to the groundwater, releasing the heat.

Open-loop system – water goes directly to the heat pump for the heat exchange and is returned to the body of water. An open system uses groundwater from a well as a heat source. For the proper operation of the heat pump, it is mandatory to have a good quality of water, free of pollutants.

Remember that you need a body of water nearby to install this type of a heat pump. So, unless you're near a lake or a pond, this option might be out of the question. However, if you are, here are some of the benefits of having a water source heat pump.

Water source heat pumps are also known as ground-source or earth-energy systems.

Benefits of water source heat pumps

Just like other types, water source heat pumps also have their benefits and advantages. But we will also briefly discuss some of their disadvantages for better-informed decision-making. Here are some advantages and disadvantages of water source heat pumps.

Installation tips and costs

First, let's focus on installation. Like geothermal heat pumps, they're harder to install compared to air-source heat pumps, but they're still relatively easier. Unlike geothermal heat pumps, water source heat pumps don't need trenches or large land areas. As long as you're near a lake or a pond, it can run properly. However, you might need additional equipment for your water source heat pump.

And remember that before installation, you might need permits from local authorities and is depending on where it will be placed. Check first with your local government units about this concern.

As for cost, they're not cheap either. In the shorter run, air source heat pumps might be the better pick. However, despite the high upfront costs of water source heat pumps, you get high payback for it. For example, in the UK, the average payback period for most domestic heat pumps is 5 years, 10 for the larger units.

And like most heat pumps, water source ones save you money and energy, in the long run, depending on what heating unit gets replaced, which leads us to its next benefit.

Energy efficiency and environmental impact

Unlike gas furnaces that generate heat, heat pumps only transfer heat from one place to another, so they require less electricity to operate. Water source heat pumps can give you up to 5 units of heat for every unit of electricity consumed. The Coefficient of Performance – COP is around 5. Furthermore, water transfers heat more efficiently than air since its temperature is more consistent and stable. When it comes to transferring heat rate, water is better than both air and ground.

Aside from the energy they consume, these units are environmentally friendly too. Because they don't depend on combustion, water source heat pumps don't emit a lot of carbon dioxide. And it's not just the air that's pollution-free. The water source used by the heat pump remains mostly unaffected as well due to their designs.

For example, open-loop systems only draw water and return it the water to the pond as it is without incident. Closed-loop systems, on the other hand, merely let the mixture gather heat as it travels through the coils. So, there's not too much to worry about polluting the water.

In the wintertime, a river, lake, or pond where the heat exchanger is installed, is warmer than the air, and due to its thermal capacity, it will retain some of the solar heat, making it more efficient than the air heat pumps.

Unit maintenance and durability

Most homeowners worry about maintaining their heat pump since it's best to keep it for as long as possible. Firstly, what is the lifespan of a water source heat pump? They last for about 15 years, sometimes 20, which is slightly more than an air source heat pump's life. Water source heat pumps can also last up to 50 years if maintained properly.

In terms of maintenance, most of it can be done for indoor components. Maintaining and repairing a water source heat pump is relatively easier compared to an air source one. For multiple units installed as a system in a large building, the system should still work even with one unit gone. Its parts are also easy to remove and replace for installation and repair. Additionally, professional technicians aren't always required in these types of settings.

However, it's a different story with an open-loop heat pump. If you're installing this kind of system, the water source should be clean. Otherwise, the heat pump will need filtration. If you choose an open-loop heat pump, you'll have to watch over the water filter. Regardless, water source heat pumps still require regular tune-ups and maintenance.

Disadvantages

  • Requires a permit
  • Requires a reliable source of water nearby
  • Requires electricity
  • Engineering challenges
  • Cannot store summer heat for use in winter
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Comparison to other heat pump types

We have talked about what makes water source heat pumps worthy investments. Now we will make quick comparisons of a water source, air source, and geothermal heat pumps. Besides their heat sources, there are notable differences among these three, like lifespan and cost, among other things. Comparing these three heat pump types will give you more of an idea of what you're investing in.

Lifespan and durability

  • Air-source heat pumps – they usually last for an average of 15 years, and their lifespan can decrease depending on location. This type of heat pump can only last for 7 to 12 years in coastal areas where it's more prone to corrosion. Air source heat pumps need more constant maintenance due to its exposure to the elements.
  • Geothermal heat pumps – they can last for more than 20 years, and its loops can last for almost 50 years at best. It doesn't require much maintenance except for its indoor component. Geothermal heat pumps are protected from the elements because of its underground installation.
  • Water-source heat pumps – like geothermal heat pumps, they can also last for 15 to 20 years. With proper maintenance, this type of heat pumps can even last for as long as 50 years. However, with open-loop systems, they require filtrations, especially if the water source isn't clean.

Cost and installation

While all three units are somewhat costly, their installation methods and costs in the long run still differ.

  • Air-source heat pumps – this type of a heat pump is relatively cheaper and easier to install in the shorter run.
  • Geothermal heat pumps – out of all three, geothermal heat pumps have the highest upfront costs. They also require a huge land area and trenches for installation. However, it still saves money in the long run.
  • Water-source heat pumps – they have high installation costs but a good payback in the long run. Compared to geothermal heat pumps, they are relatively easier and cheaper to install. However, they require quality and a sufficient amount of water nearby. Clean water is better, especially if you'll install an open-loop system.

Conclusion

Here are some of the comparisons among the three heat pump types. The conclusion is that water source heat pumps are good investments in the long run. They also provide year-round comfortable and reliable heating in the winter and cooling in the summer, that, when combined with other types of HVAC equipment, can significantly reduce your energy bills. However, the choice is yours at the end of the day. It's important to choose the appropriate heat pump for your needs and availability.

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