How to Install a Reserve Tank

Installing a reserve tank can be a game-changer for homeowners struggling with hot water shortages. They provide an ample supply of hot water for high-demand fixtures like deep-soaking bathtubs or multi-head showers. In this guide, we’ll explore the process of installing a reserve tank, drawing insights from plumbing expert Richard Trethewey, who demonstrates the process in the video above.

Understanding the Need for a Reserve Tank

Many homeowners mistakenly believe they have an on-demand water heater when they have a combi unit with a limited water tank. This misunderstanding can lead to frustration, particularly when filling large tubs or when multiple people are using hot water at the same time. 

Combi units that attempt to meet dual demands of home heating and water heating often fall short in situations with high demand. The limitation stems from the combi unit’s inability to heat water quickly enough to sustain a high flow rate over an extended period.

Identifying Hot Water Shortages

Hot water shortages often manifest as:

• Tub water cooling before the tub is full
• Showers running cold prematurely
• Multiple hot water appliances are unable to run simultaneously

When these scenarios occur regularly, it’s a clear sign that your hot water system isn’t keeping up with your household’s needs.

Assessing Your Hot Water Needs

Before installing a reserve tank, you should understand your household’s hot water requirements. Knowing how much hot water you use and when it is most in demand will help you choose the right tank size and set your system up for success.

Calculating Water Usage and Peak Demand

To determine your hot water needs:

1. Measure the capacity of your largest tub or appliance
2. Consider peak usage times when multiple hot water sources may be in use
3. Factor in the flow rate of your fixtures, especially tub fillers, which can exceed seven gallons per minute

Additionally, think about your household’s lifestyle. For example, families who often run the dishwasher, washing machine, and multiple showers at the same time will need a larger reserve tank compared to smaller households.

Choosing the Right Size Reserve Tank

The size of your reserve tank should match your peak hot water demands. For most households with large tubs, an 80-gallon tank is more than enough. This size gives your family ample hot water for filling a 60-gallon tub while leaving a buffer for other simultaneous uses. Larger tanks, such as those exceeding 100 gallons, may be necessary for particularly high-demand households or those with luxury bathroom setups with multiple high-flow fixtures.

Preparing for a Reserve Tank Installation

Before starting the installation process, you’ll need to gather the right materials and pick an optimal location. Keep in mind that adding a reserve tank to your home is complicated, so if you have little experience with plumbing, it’s worth hiring a licensed plumber. Either way, being well-prepared will streamline the process and minimize complications.

Gathering Materials and Tools

Ensure you have the following on hand:

• Reserve tank (80-gallon capacity recommended)
• Expansion tank
• Bronze pump
• Copper piping and fittings
• Hose and bucket for draining
• Thread tape and pipe dope
• Tubing cutter
• Wrenches and pliers

Safety equipment, such as gloves and protective eyewear, is also essential, especially when completing the project yourself.

Selecting the Installation Location

Choose a location for your reserve tank that is:

• Close to the existing water heater or combi unit
• In an area not prone to freezing
• Accessible for maintenance and repairs
• Able to support the weight of a full tank

When picking the location, also consider the distance hot water will need to travel to reach your fixtures. Placing the reserve tank closer to high-demand fixtures can reduce heat loss in the pipes and improve system efficiency.

Reserve Tank Installation Process

Installing a reserve tank involves several key steps. While a skilled DIYer might tackle this project, it’s often best left to professionals due to the complexity of plumbing and potential safety issues.

Step 1: Shutting Off Power and Water

Begin by turning off the power and gas to your combi boiler or on-demand water heater. Then, shut off the water supply and drain the existing tank using a hose and bucket. Double-check that all power sources are disconnected to avoid any accidental electrocution or gas leaks.

Step 2: Cutting and Preparing Pipes

Cut the piping that runs from the boiler’s tank to the system, as well as the return side. This allows you to connect the reserve tank’s outlet into the existing system. Measure and cut precisely to avoid any mistakes that could lead to leaks or misalignment.

Step 3: Installing the Expansion Tank

Install a new expansion tank between the boiler’s tank and the new reserve tank. The expansion tank helps manage pressure in the closed system. Without it, the pressure from ‌heated water could damage your pipes or the tank itself.

Step 4: Connecting the Reserve Tank

Connect the tank’s outlet pipe to the reserve tank’s inlet. Install a bronze pump on the outlet side of the reserve tank and connect it to the return side of the system. The pump will help maintain the flow of hot water from the reserve tank to your fixtures.

Step 5: Purging Air and Refilling

Slowly turn on the water to purge air from the boiler. Open a faucet valve and keep it open until water flows continuously without hissing or burping, indicating all air has been removed from the system. Air pockets can cause inconsistent water flow and reduce the efficiency of your system, so don’t skip this step.

Step 6: Reactivating the System

Turn the combi boiler back on and allow it to heat and circulate water through the new reserve tank. Check the system for any leaks or unusual noises. If everything is functioning correctly, you should have a steady supply of hot water, even during peak usage times.

Optimizing Your New Reserve Tank Hot Water System

Once your reserve tank is installed, there are steps you can take to ensure it operates at peak efficiency. Regular maintenance and proper system settings can extend the life of your tank and prevent issues before they arise.

Setting the Right Temperature

Set the storage tank to the desired temperature, typically between 120°F and 140°F. Remember that the boiler’s high limit should be set at least 20 degrees higher than the storage tank temperature setting. This ensures that the water in the reserve tank is always replenished with sufficiently hot water.

Regular Maintenance

Here are some tips to keep your system running smoothly:

• Flush the tank annually to remove sediment
• Check for leaks and corrosion regularly
• Inspect the anode rod (if applicable) every few years
• Test the pressure relief valve periodically

Regular maintenance helps prevent buildup that can reduce efficiency or cause damage. For homes with hard water, more frequent flushing may be necessary to remove mineral buildup.

Reserve Tank Cost Considerations

The cost of installing a reserve tank can vary widely depending on factors such as tank size, labor costs, and any necessary modifications to your existing system. On average, homeowners can expect to pay between $1,614 and $3,051 for a complete installation, including the tank.*

*Cost information according to contractor estimates used by Angi.

Factors Affecting Cost

Several elements can influence the overall cost:

• Complexity of the installation
• Local labor rates
• Size and quality of the reserve tank
• Any required upgrades to existing plumbing or electrical systems

Upgrading your plumbing system might involve additional costs, particularly if new pipes, fittings, or support structures are needed. Consulting a professional beforehand can give you a more accurate estimate and help you budget accordingly.

Long-Term Savings

While the upfront cost may seem significant, a reserve tank can lead to long-term savings through:

• Extended life of your primary water heater
• Increased home value and appeal to potential buyers
• Reduced energy consumption by minimizing the need for constant reheating

In addition to these benefits, having a reliable supply of hot water can enhance your daily living experience, making tasks like bathing, cooking, and cleaning more comfortable and efficient.

Our Conclusion

Installing a reserve tank is the best solution for homeowners facing hot water shortages, especially those with large tubs or high-demand households. While the installation process can be complex, the benefits of consistent hot water supply and potential energy savings make it a worthwhile investment for many homes.

Water heater products were manufactured by Heat Transfer Products (HTP) and Jomar Distributors.

Expert assistance provided by Papalia Home Services