Can I Add an Extra Tank to My Air Compressor

Yes, you can absolutely add an extra tank to your air compressor. This common upgrade is a fantastic way to boost your system’s air storage capacity and performance. It solves the frustrating problem of frequent compressor cycling and low air volume.

This modification provides a larger reservoir of compressed air for your tools. You’ll experience longer run times and more consistent pressure, enhancing your workshop’s efficiency. It’s a cost-effective alternative to buying a whole new, larger compressor unit.

Best Add-On Tanks for Your Air Compressor – Detailed Comparison

HPDAVV 30-Gallon Vertical Air Tank – Best Overall Choice

This ready-to-use auxiliary tank is a top pick for its complete, pre-assembled kit. It includes a pressure gauge, drain valve, and safety valve, making installation straightforward. Its 30-gallon capacity offers a significant boost for most home workshops, providing longer tool runtime between compressor cycles.

DEWALT 20V MAX Powered Portable Water Tank – Best for Mobility

Ideal for job sites or mobile mechanics, this portable tank features rugged construction and easy-transport handles. The 8-gallon size is perfect for supplementing smaller pancake or hot dog compressors. It includes a quick-connect coupler for fast tool changes, enhancing your workflow away from a stationary air source.

Performance Tool11-Gallon Horizontal Tank – Best for Permanent Installation

This horizontal ASME-certified tank is the ideal, durable core for a custom plumbed system. Its robust design supports permanent installation in a workshop garage. The 11-gallon capacity is excellent for smoothing out demand from multiple tools, reducing wear on your primary compressor’s motor.

Key Benefits of Adding a Secondary Air Compressor Tank

Expanding your air storage offers immediate, tangible improvements to your workshop’s performance. This upgrade directly addresses common limitations of smaller compressor systems. The advantages extend beyond just having more air available on demand.

Enhanced Tool Performance and Runtime

A larger air reservoir allows tools to run longer and more consistently. Your compressor motor cycles on less frequently, reducing wear. This is crucial for air-hungry tools like sanders, grinders, or paint sprayers.

• Longer Continuous Use: Tools can operate for extended periods before tank pressure drops and the compressor must restart.
• Stable Pressure: A secondary tank helps mitigate pressure drops, providing a steadier airflow for consistent tool power.
• Handles High-Demand Tools: It enables the use of tools that require a higher CFM (Cubic Feet per Minute) than your primary compressor can supply continuously.

Increased System Efficiency and Longevity

Reducing the cycle frequency of your main compressor is one of the best things you can do for its lifespan. Every time the motor starts, it undergoes significant stress and heat buildup.

An auxiliary tank acts as a buffer. It allows the compressor to fill both tanks and then rest for a longer period. This leads to cooler operation and less mechanical fatigue over time.

Key Takeaway: The core benefits are longer tool runtimes, stable pressure, and reduced wear on your primary compressor motor, leading to lower maintenance costs and longer equipment life.

Practical Workshop Applications

Consider a scenario where you’re using a die grinder that consumes more CFM than your compressor can sustain. Without an extra tank, the tool will quickly drain the reservoir, causing the compressor to run constantly.

With added storage, the compressor fills the large combined volume and shuts off. You then have a substantial reserve of air to draw from, allowing you to work uninterrupted. This setup is also perfect for running multiple lower-CFM tools simultaneously from a single air source.

How to Connect an Additional Tank to Your Air System

Connecting an auxiliary tank is a straightforward process with the right parts and planning. Safety and correct component selection are paramount for a reliable and leak-free system. This guide outlines the essential steps and required fittings.

Essential Components and Fittings You’ll Need

Gathering the correct parts before you start is crucial for a smooth installation. You will need more than just the new tank itself. The right connectors ensure safe operation at your system’s working pressure.

• Pipe Fittings: NPT (National Pipe Taper) fittings, tees, elbows, and nipples to route air between tanks.
• Shut-Off Valves: Install valves on both tanks to isolate them for maintenance or in case of a leak.
• Pressure-Rated Hose: Use a flexible, reinforced hose rated for your compressor’s maximum PSI if a rigid pipe connection isn’t practical.
• Thread Sealant: Always use PTFE tape or pipe dope on all threaded connections to prevent air leaks.

Step-by-Step Installation Process

Follow this logical sequence to ensure a safe and functional connection. Always depressurize your entire system completely before beginning any work.

1. Depressurize and Plan Layout: Drain all air from your primary compressor and plan the physical placement of the new tank for optimal airflow and accessibility.
2. Install the Main Connection: Using a tee fitting, connect your air line from the compressor’s outlet to the inlet ports of both the original and new tank.
3. Add Safety and Control Valves: Ensure each tank has its own drain valve at the lowest point. Install a shut-off valve on the line to the auxiliary tank.
4. Pressure Test for Leaks: Close all drains and tool outlets. Pressurize the system and spray all connections with soapy water to check for bubbles indicating leaks.

Pro Tip: For the safest and most efficient airflow, use the largest diameter piping or hose possible between tanks. This reduces pressure drop and allows the auxiliary tank to fill quickly.

Critical Safety Considerations and Pressure Management

Working with pressurized air systems requires strict adherence to safety protocols. Ignoring these can lead to equipment failure or dangerous accidents. Proper pressure management is the cornerstone of a safe and functional dual-tank setup.

Pressure Ratings and ASME Certification

Never install a tank that cannot handle your compressor’s maximum output pressure. Every pressure vessel has a maximum working pressure (MWP) stamped on its data plate. This is a non-negotiable safety limit.

• ASME Certification: Always use an auxiliary tank certified by the American Society of Mechanical Engineers (ASME). This ensures it was manufactured to rigorous safety standards.
• Match or Exceed Primary Tank: The new tank’s MWP must be equal to or greater than your main compressor tank’s rating. Using an under-rated tank is extremely hazardous.
• Respect the Pressure Switch: Your compressor’s pressure switch controls the cut-in and cut-out pressure. The entire system, including the add-on tank, will be pressurized to this cut-out level.

Mandatory Safety Devices and Maintenance

Your secondary tank must be equipped with the same safety features as your primary one. These devices are critical fail-safes that prevent catastrophic over-pressurization.

The pressure relief valve is the most important component. It automatically releases air if the pressure exceeds a safe level. Test this valve periodically by manually pulling the ring to ensure it isn’t stuck.

Regular maintenance is non-optional. You must drain moisture from both tanks daily after use to prevent internal rust. Inspect all fittings and hoses regularly for signs of wear, cracks, or leaks.

Safety Summary: The three absolute rules are: 1) Use only ASME-certified tanks, 2) Ensure the tank’s pressure rating matches or exceeds your system’s max PSI, and 3) Equip it with a functioning pressure relief valve.

System Pressure Dynamics

Adding a tank increases total air volume but does not increase pressure. Your compressor will work longer to fill the combined volume to its cut-out pressure. Conversely, it will take longer for the pressure to drop to the cut-in point, giving your motor more rest.

This dynamic reduces motor cycles but means recovery time (time to refill tanks from empty) is longer. Plan your work accordingly, allowing the system to fully pressurize before starting a demanding task.

Evaluating Your Compressor: Is It Suitable for an Extra Tank?

Not every air compressor is an ideal candidate for this upgrade. Adding capacity strains the pump and motor during the fill cycle. A proper evaluation ensures your primary unit can handle the increased demand without failing prematurely.

Assessing Compressor Pump and Motor Capacity

The key factor is your compressor’s CFM (Cubic Feet per Minute) output at its working pressure. A small, low-CFM pump will struggle to fill a significantly larger total volume. This leads to excessively long run times and motor overheating.

• CFM vs. Tank Size: A general rule is that your compressor should fill its total tank volume (original + new) to pressure within a reasonable time (e.g., 2-4 minutes for workshop use).
• Duty Cycle: Check your compressor’s duty cycle (e.g., 50%). This is the percentage of time it can run within a 10-minute period. Adding too much tank volume can force it to exceed this limit.
• Motor Power: Larger tank volume requires more work from the motor during each cycle. Ensure your motor is adequately powered and not already operating at its thermal limit.

When to Upgrade vs. When to Buy a New Compressor

This decision hinges on cost, your existing compressor’s health, and your air needs. Adding a tank is a cost-effective solution for a robust compressor that just needs more storage.

Consider the following comparison to guide your decision:

Situation	Add a Tank	Buy a New Compressor
Primary Issue	Frequent cycling, short tool runtime	Insufficient CFM, low pressure
Compressor Health	Strong motor & pump in good condition	Old, underpowered, or failing unit
Cost Consideration	Lower upfront investment	Higher cost for a complete system
Best For	Extending the life of a capable unit	Meeting substantially higher air demands

Takeaway: If your compressor has a healthy, adequately sized pump but the tank empties too fast, adding storage is smart. If the pump itself can’t deliver enough continuous CFM for your tools, you need a larger compressor.

Advanced Configurations and Professional Setup Tips

For users with demanding needs, a simple parallel connection might not be optimal. Advanced plumbing can unlock greater efficiency and control. These professional setups are ideal for permanent workshop installations.

Manifold Systems and Dedicated Tool Lines

Instead of daisy-chaining tanks, consider feeding both from a central air manifold. This is a distribution block with multiple outlet ports. It creates a more organized and efficient hub for your entire air system.

• Centralized Control: A manifold allows you to install a main filter, regulator, and lubricator (FRL) that conditions air for all downstream tools simultaneously.
• Dedicated Drops: You can run separate air lines with their own regulators from the manifold to different workstations. This lets you set specific pressures for painting, impact tools, and cleaning.
• Isolation Valves: Include individual shut-off valves for each tank and tool line on the manifold. This enables maintenance without depressurizing the entire system.

Optimizing Airflow and Reducing Pressure Drop

The goal is to deliver the maximum volume of air with the least resistance. Poor plumbing creates bottlenecks that negate the benefits of your extra tank.

Follow these principles for optimal performance:

1. Use Large Diameter Piping: For main trunk lines, use the largest feasible pipe size (e.g., 3/4″ or 1″). This dramatically reduces friction loss compared to standard 1/4″ or 3/8″ hoses.
2. Minimize Elbows and Length: Plan the shortest, most direct route between the compressor, tanks, and manifold. Use sweep elbows instead of sharp 90-degree fittings where possible.
3. Slope and Drain: Install all piping with a slight slope back toward the tanks or to dedicated drain points. This allows condensed moisture to flow out of the lines automatically.

Pro Insight: For a high-performance shop, the ideal hierarchy is: Compressor → Large Main Tank → Air Manifold with FRL → Dedicated Drops to workstations. The auxiliary tank acts as a primary reservoir, not just an add-on.

Incorporating an Aftercooler or Dryer

Larger air volume means more moisture condensation. If you use tools sensitive to water (like sandblasters or paint guns), consider adding an aftercooler or refrigerated dryer between the compressor and the tanks. This protects your tools and your new investment from internal rust.

Common Installation Mistakes and How to Avoid Them

Even a simple upgrade can go wrong if critical details are overlooked. These common errors can lead to poor performance, safety hazards, or system failure. Learning from others’ mistakes ensures your project is successful and durable.

Plumbing and Connection Errors

Improper fittings and routing are the most frequent sources of problems. They create leaks, restrict airflow, and introduce moisture traps into your system.

• Using Non-Pressure-Rated Components: Never use plumbing fittings from a hardware store meant for water. Always use industrial-grade air fittings rated for your system’s maximum PSI.
• Undersized Hoses or Pipes: Connecting tanks with a small-diameter hose (like 1/4″) creates a major bottleneck. This severely limits flow and negates the benefit of the extra tank’s volume.
• Creating Moisture Traps: Running a hose with a low spot or “U” shape between the compressor and tank will collect water. This liquid can be carried into your tools or cause internal tank rust.

Safety and Configuration Oversights

Neglecting safety devices or misunderstanding system dynamics can have serious consequences. These mistakes often stem from trying to cut corners or using incompatible parts.

One critical error is failing to install a check valve if your auxiliary tank is positioned lower than the primary. Without it, condensed water from the main tank can drain back into the compressor pump, causing severe damage.

Another is mismatching pressure ratings, as previously warned, or using a tank with a faulty or missing pressure relief valve. Never assume an old, used tank is safe without a thorough inspection for internal corrosion.

Avoid These Pitfalls: 1) Never use water pipe fittings for air. 2) Ensure all hoses are pressure-rated and large enough in diameter. 3) Install a check valve if needed to prevent backflow. 4) Always pressure-test with soapy water.

Misunderstanding System Performance

A common misconception is that an extra tank will increase your compressor’s CFM output. It does not. The pump produces the same CFM; it just has more storage to fill.

This means recovery time (from empty to full) will be longer. Users sometimes mistake this longer fill time for a compressor problem. The benefit is the extended time you can use air before the pressure drops low enough to trigger the motor.

Cost Analysis: Adding a Tank vs. Buying a Larger Compressor

The financial decision is a major factor for most DIYers and shop owners. Adding an auxiliary tank is typically far less expensive than purchasing a new, larger compressor. However, you must weigh the upfront cost against long-term value and performance.

Breaking Down the Expenses

The total cost of a tank addition includes more than just the tank itself. You must budget for all necessary fittings, valves, and piping to complete a safe installation.

• Auxiliary Tank: $100 – $300+ for a quality ASME-certified tank, depending on size (e.g., 10-gallon to 30-gallon).
• Fittings & Plumbing: $50 – $150 for pressure-rated fittings, shut-off valves, pipe, hose, thread sealant, and brackets.
• Your Time/Labor: A DIY installation takes 2-4 hours for a basic setup. Professional installation could add $200-$500.
• New Large Compressor: $500 – $2,000+ for a unit with a significantly larger built-in tank and higher CFM pump.

When the Upgrade Makes Financial Sense

Adding a tank is most cost-effective when your existing compressor is mechanically sound and meets your CFM needs for short bursts. You are essentially paying for more “battery” capacity, not a more powerful “engine.”

This upgrade extends the useful life of your current equipment. It delays a much larger capital expenditure. If your primary compressor is relatively new and high-quality, boosting its capacity is a smart investment.

Cost-Benefit Verdict: If your compressor’s pump is sufficient but its tank is too small, adding storage for under $500 is excellent value. If the pump is underpowered, spending $1,000+ on a new, correctly sized compressor is the better long-term investment.

Considering Hidden Costs and Value

Factor in the ongoing costs of both options. A new compressor may have a better warranty and improved efficiency. Your old unit, even with a new tank, will still have an older motor and pump with unknown remaining lifespan.

Conversely, the upgrade path has minimal hidden costs if done correctly. The new tank itself will last for decades with proper maintenance. The value lies in maximizing the utility of equipment you already own.

Conclusion: Expanding Your Air Compressor’s Capacity Successfully

Adding an extra tank to your air compressor is a proven and effective upgrade. It delivers longer tool runtimes, more stable pressure, and reduced motor wear. This project can transform your workshop’s capabilities without a major investment.

The key to success is prioritizing safety with ASME-certified tanks and proper pressure ratings. Always perform a thorough leak test after installation. This ensures your system is both powerful and reliable.

Now, assess your compressor’s pump capacity and your air needs. Gather the right fittings and follow the steps outlined. You’re ready to build a more efficient air system that meets your demands.

Take action on this straightforward upgrade. Enjoy the immediate benefits of a professional-grade air supply in your own shop.

Frequently Asked Questions About Adding an Air Compressor Tank

What is the best size for an auxiliary air compressor tank?

A good rule is to match or slightly exceed your primary tank’s volume. For a common 20-gallon compressor, a 20-30 gallon add-on is ideal. This provides a significant capacity boost without overloading the pump.

Consider your CFM needs and available space. Too large a tank can lead to excessively long fill times if your compressor pump is small. Balance increased storage with practical recovery time.

How do you connect two air compressor tanks together safely?

Use a tee fitting to split the air line from your compressor’s outlet. Connect one line to each tank’s inlet port. Install individual shut-off valves and ensure both tanks have their own pressure relief valves.

Always use pressure-rated fittings and hose. Apply PTFE tape to all threads and perform a soapy water leak test on every connection after pressurizing the complete system.

Does adding a second tank increase CFM?

No, adding a tank does not increase your compressor’s CFM (Cubic Feet per Minute) output. The pump produces the same volume of air. The tank only increases storage capacity, like a larger battery.

You gain longer runtime at your tool’s required CFM before pressure drops. For higher continuous CFM, you need a compressor with a more powerful pump, not just more tank volume.

Can I use any old propane tank as an extra air tank?

Absolutely not. This is extremely dangerous. Propane tanks are not designed for compressed air service and lack the required ASME certification and safety features. They can corrode internally and fail catastastically.

Only use tanks specifically manufactured and certified for compressed air. Look for the ASME stamp on the data plate. Your safety depends on using the correct pressure vessel.

What is the purpose of a check valve when adding an auxiliary tank?

A check valve allows air to flow in only one direction. It is crucial if your secondary tank is mounted at a lower elevation than your primary compressor. It prevents water and condensation from the main tank from draining back into the compressor pump.

This backflow can cause severe hydraulic damage to the pump. Install the check valve in the line leading to the lower tank to ensure one-way flow from the compressor outward.

How much does it typically cost to add an extra air tank?

A complete DIY setup typically costs between $150 and $500. This includes an ASME-certified tank ($100-$300), all necessary pressure-rated fittings, valves, and piping ($50-$150). The cost varies greatly with tank size and connection complexity.

This is often far less expensive than buying a new, larger compressor. It is a cost-effective way to extend the capability and lifespan of your existing system.

Why is my compressor running longer after I added a second tank?

This is normal and expected. Your compressor now has a larger total volume to fill to its cut-out pressure. The motor will run for a longer continuous period to pressurize both tanks completely.

The benefit is that it will also rest longer between cycles. The increased run time per cycle is offset by fewer cycles overall, which reduces motor wear and heat buildup.

What is the most common mistake when installing an add-on air tank?

The most common error is using undersized or non-pressure-rated plumbing. Household water fittings and small-diameter hoses create dangerous bottlenecks. They restrict airflow and can fail under pressure.

Always use industrial air components rated for your system’s maximum PSI. Ensure hose and pipe diameters are large enough (3/8″ minimum, 1/2″ or larger preferred) to allow free airflow between tanks.