How does a hot water system work?

How does a hot water system work?

What is a hot water system?

A hot water system is an appliance that heats and stores hot water for your home’s taps and showers. It’s essential for everyday tasks like showering, washing dishes, and doing laundry. There are two main types:

  • Storage systems: These heat water in a tank and keep it hot until you need it. They’re the most common type and come in gas or electric models.

  • Instantaneous systems: These heat water only when you turn on the tap, so they’re more energy-efficient. However, they may not be suitable for homes with high hot water demand.

How do electric hot water systems work?

Electric hot water systems come in two main varieties: storage and instantaneous. They both use electricity to heat water, but how they store and deliver it differs.

Storage Systems:

  1. Heating: These systems have a large insulated tank that holds the hot water. Inside the tank, one or two heating elements, typically made from nickel-chrome alloy or copper, are located near the bottom. When electricity flows through these elements, resistance creates heat, which warms the surrounding water.

  2. Thermostat Control: A thermostat is installed within the tank to regulate the water temperature. It automatically turns the heating element on and off to maintain a set temperature, usually around 60°C (140°F) to prevent bacteria growth.

  3. Hot Water Delivery: Cold water enters the tank at the bottom. As the water gets heated, it naturally rises due to lower density. This creates a layered effect with the hottest water at the top of the tank, ready for use when you turn on a hot water tap.

  4. Insulation: The tank is well-insulated to minimise heat loss, keeping the stored water hot for longer and reducing energy consumption.

Instantaneous Systems (also known as Continuous Flow or Tankless):

  1. On-Demand Heating: Unlike storage systems, these systems don’t have a tank. Instead, they heat water only when you turn on the hot water tap. Cold water flows through a heat exchanger within the unit.

  2. Heat Exchanger: The heat exchanger is where the magic happens. It contains powerful electric heating elements that rapidly heat the water as it passes through.

  3. Hot Water Delivery: The heated water is then immediately delivered to your hot water tap. Since there’s no storage tank, there’s no standby heat loss, making them potentially more energy-efficient than storage systems.

How long does an electric hot water system last?

Typically, expect it to last between 10 and 15 years. These are the factors that can make the difference;

  • Type of System: Storage tank systems tend to have a shorter lifespan than tankless (instantaneous) systems. Storage tanks are more prone to internal corrosion from mineral buildup and pressure fluctuations, which can lead to leaks and malfunctions.

  • Water Quality: Hard water, with high mineral content, can accelerate corrosion in storage tanks, reducing their lifespan. In areas with hard water, you might see the lifespan drop by a couple of years.

  • Maintenance: Regular maintenance, like checking and replacing the anode rod (sacrificial component that attracts corrosion) in storage tanks, can extend the lifespan of your system.

How do gas hot water systems work?

Gas hot water systems, like their electric counterparts, come in storage and instantaneous varieties. Both utilise natural gas or propane to heat water, but the process differs slightly.

Storage Systems:

  1. Gas Burner: Located beneath the insulated water tank, a gas burner ignites when the water temperature dips below the set point on the thermostat.

  2. Heat Transfer: The burning gas heats a metal heat exchanger located within the tank. This heat exchanger efficiently transfers heat from the combustion chamber to the surrounding water.

  3. Thermostat Control: Similar to electric systems, a thermostat regulates the water temperature. It turns the gas burner on and off to maintain the desired temperature, typically around 60°C (140°F).

  4. Hot Water Delivery: Cold water enters the tank at the bottom and is heated by the surrounding hot water. Hot water naturally rises and is delivered to your taps when needed. The tank’s insulation helps retain heat, minimising energy consumption.

Instantaneous Systems (also known as Continuous Flow or Tankless):

  1. On-Demand Heating: There’s no storage tank in these systems. Instead, a flow sensor detects when you turn on a hot water tap.

  2. Gas Burner and Heat Exchanger: Upon sensing water flow, the system activates. A gas burner ignites, heating a heat exchanger. Cold water passes through this heat exchanger, getting rapidly heated in the process.

  3. Hot Water Delivery: The instantly heated water is delivered directly to your hot water tap. Since there’s no storage, there’s no standby heat loss, making them potentially more energy-efficient than storage systems.

  4. Safety Features: These systems often have safety features like flue gas sensors and automatic shut-off mechanisms to prevent gas leaks or overheating.

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How long should a gas hot water system last?

On average, a gas hot water system can last between 8 and 12 years. Here’s a deeper look at the factors affecting their lifespan:

  • Type of System: Similar to electric systems, tankless gas hot water heaters generally outlast storage tank models. Storage tanks are more susceptible to corrosion and pressure fluctuations that can lead to leaks and malfunctions. Tankless systems experience less wear and tear due to on-demand heating.

  • Water Quality: Hard water, high in minerals, can accelerate corrosion in storage tanks, shortening their lifespan. This impact might be more significant in areas with particularly hard water.

  • Maintenance: For storage tanks, this includes checking and replacing the anode rod (a sacrificial component that attracts corrosion) to extend system life.

  • Ventilation: Proper ventilation is essential for gas systems to function safely and efficiently.

Are heat pump hot water systems worth it?

Heat pump hot water systems can be a worthwhile option, but it depends on several factors:

Pros:

  • Energy Efficiency: They are significantly more energy-efficient than traditional electric hot water heaters, potentially reducing your electricity bills. They achieve this by extracting heat from the surrounding air instead of generating it with electricity.

  • Environmentally Friendly: Due to their lower energy consumption, they have a smaller carbon footprint compared to electric or gas systems.

  • Lower Running Costs: Over time, the savings on your electricity bill can outweigh the upfront cost of the system.

  • Fewer Safety Risks: They don’t involve combustion, eliminating the risks associated with gas hot water systems like gas leaks or carbon monoxide poisoning.

  • Long Lifespan: Heat pump hot water heaters can last up to 15 years with proper maintenance.

Cons:

  • Higher Upfront Cost: Heat pump hot water heaters typically cost more than traditional electric or gas hot water heaters.

  • Lower Efficiency in Colder Climates: While they work in most climates, their efficiency can decrease significantly in very cold environments – not relevant for us in QLD!

  • Slower Hot Water Recovery: They may take longer to heat water compared to traditional hot water heaters, especially if there’s high hot water demand in your household.

  • Installation Requirements: They require space for the outdoor unit and may need additional plumbing compared to traditional systems.

Additional considerations include;

  • Your Climate: If you live in a mild climate, a heat pump hot water system can be a very efficient choice. However, if you live in a cold climate, you might be better off with a traditional gas or electric system, so keep this in mind when reading reviews.

  • Hot Water Usage: Use a lot if water? A heat pump hot water system might struggle to keep up with demand.

  • Government Rebates: Unfortunately, the Climate Smart Energy Savers rebate that provided rebates for solar and heat pump hot water systems closed in December 2023.

Overall, heat pump hot water systems are a promising energy-efficient technology. If you live in a mild climate with moderate hot water usage and are looking for a long-term environmentally friendly option, then a heat pump hot water heater could be a worthwhile investment.

How long does a hot water system last?

The lifespan of a hot water system in Queensland can vary depending on the type of system and several other factors. Here’s a general breakdown:

Electric Hot Water Systems:

  • Storage Tanks: In QLD, you can expect an electric storage hot water system to last around 8-12 years.

  • Tankless: These can potentially last longer, up to 15 years.

Gas Hot Water Systems:

  • Storage Tanks: Similar to electric storage systems, gas storage tank hot water heaters in QLD typically last 8-12 years.

  • Tankless: Tankless gas hot water systems can last up to 12 years or even longer.

Heat Pump Hot Water Systems:

  • With proper care, heat pump hot water heaters in Queensland can last around 10-15 years.

Here are some additional factors that can influence the lifespan of your hot water system:

  • Water Quality: The presence of hard water, high in minerals, can accelerate corrosion in storage tanks, reducing their lifespan. This might be more noticeable in some areas of QLD compared to others.

  • Maintenance: Regular maintenance, like checking and replacing the anode rod in storage tanks, can significantly extend the system’s life.

  • Manufacturer Warranty: The warranty period offered by the manufacturer can be a good indicator of the expected lifespan. It typically ranges from 5 to 12 years.

Climate Considerations:

In general, the mild climate of Queensland shouldn’t significantly impact the lifespan of hot water systems compared to colder regions.

How much electricity does a hot water system use?

The amount of electricity a hot water system uses in and around Brisbane depends on several factors:

  • Type of System:

    • Electric Storage: These are generally the least efficient and can use anywhere between 2,000 kWh and 4,000 kWh of electricity per year in QLD, depending on the size and insulation level of the tank.

    • Electric Tankless (Instantaneous): These can be more efficient than storage systems, potentially using 30-50% less electricity. Their usage depends on your hot water consumption habits.

    • Heat Pump: These are the most energy-efficient option, using up to 70% less electricity than traditional electric hot water systems. They typically use around 1,200 kWh to 2,000 kWh per year in QLD.

  • Size of the System: Larger hot water systems naturally use more electricity to heat the larger volume of water.

  • Insulation Level: A well-insulated hot water tank minimises heat loss, reducing energy consumption.

  • Hot Water Usage: The more hot water you use, the more electricity the system will use to heat it.

  • Tariff: If you’re on an off-peak electricity tariff, you can potentially reduce your hot water heating costs by scheduling the system to operate during off-peak hours when electricity prices are lower.

What size hot water system do I need?

Here’s a general guideline to get you started (based on electric storage hot water systems):

  • Small household (1-2 people): 100L – 150L

  • Medium household (3-4 people): 150L – 250L

  • Large household (5+ people): 250L – 400L

How to flush hot water system

Here’s a guide on how to flush your hot water system:

Safety Precautions:

  • Turn off the power: For electric hot water systems, turn off the power at the switchboard before you begin. For gas hot water systems, turn off the gas supply valve.

  • Turn off the cold water supply: Locate the shut-off valve for the cold water inlet pipe to your hot water system and turn it off completely.

  • Allow the water to cool: Hot water can cause serious burns. Wait for at least an hour to allow the water in the tank to cool down before proceeding.

Flushing Process:

  • Attach the hose: Locate the drain valve on your hot water system. It’s usually a small valve near the bottom of the tank. Attach one end of the garden hose to the drain valve and secure it tightly with a hose clamp (if available).

  • Open a hot water tap: Open a hot water tap furthest away from the heater (e.g., bathroom or kitchen sink). This will help air enter the tank as it drains.

  • Drain the tank: Open the drain valve slowly using the wrench or pliers. Be prepared for a rush of water. You can direct the hose to a drain or empty it into a bucket.

  • Flush the sediment: Once most of the water has drained, turn on the cold water supply slightly for a short period (15-20 seconds) to agitate any sediment at the bottom of the tank. This will help loosen any buildup and flush it out. Then, close the cold water supply again and let the tank drain completely. Repeat this process of opening the cold water supply for short bursts and draining a few times to remove any loose sediment.

  • Close the drain valve: Once you’re satisfied that most of the sediment has been flushed, firmly close the drain valve using the wrench or pliers.

  • Turn on the cold water supply: Slowly turn on the cold water supply valve to refill the tank. Keep the hot water tap open you opened earlier to allow air to escape from the system. You’ll see sputtering or air bubbles initially.

  • Close the hot water tap: Once water flows steadily from the hot water tap without sputtering, close the tap.

  • Turn on the power (electric) or gas (gas): For electric systems, turn the power back on at the switchboard. For gas systems, turn the gas supply valve back on and follow the manufacturer’s instructions for re-lighting the pilot light (if applicable).

    Why is my hot water system leaking?

    There are several reasons why your hot water system might be leaking. Here are some of the most common culprits:

    Leaking hot water tank can be caused by;

    • Corrosion: Over time, especially with hard water, the interior tank can rust and develop holes.

    • Pressure Relief Valve Failure: The pressure relief valve is a safety feature that releases pressure if it builds up too high. A faulty valve might leak constantly or fail to seal properly.

    • Cracks: Physical damage to the tank from impacts or seismic activity can cause cracks and leaks.

    • Loose Connections: Pipes or fittings connected to the tank might become loose over time due to vibrations or normal wear and tear, causing leaks at the connection points.

    • Faulty Drain Valve: A worn-out or damaged drain valve might not seal properly, leading to persistent leaks.

    • Leaking Heating Element (Electric Systems Only): In electric hot water systems, a malfunctioning heating element can cause leaks around the element seal.

    Here’s what you can do:

    • Turn off the water supply: Locate the shut-off valve for the cold water inlet pipe to your hot water system and turn it off completely. This will prevent further water damage.

    • Identify the source of the leak: Carefully inspect the tank, pipes, fittings, and valves around your hot water system to locate the exact source of the leak.

    • Call a Amalgamated Services: For most leaks, especially those involving the tank itself, it’s advisable to call us to assess the situation and recommend repairs or replacements. Attempting to fix a major leak yourself could be hazardous and might not be a permanent solution.