Where Should the Expansion Tank Be Installed on a Boiler?

A boiler expansion tank is an essential part of your central water heating system. These additions allow heated water to escape without damaging your plumbing and can last five to ten years with the proper upkeep. Still, you may wonder, “Where should the expansion tank be installed on a boiler?”

Our contractors specialize in boiler installation in Port Washington. They outline some key factors to consider before replacing your boiler expansion tank.

At Professional Services, we help hundreds of Port Washington homeowners like you get the hot water they need. Our boiler technicians can help you identify when repairs or replacements are necessary and what to expect during service. Contact us at 262-218-2636 to schedule an installation today.

1. Water Boiler Expansion Tank Basics

Furnaces and boilers provide a consistent flow of hot water to your showerheads, faucets, and utilities. However, heat can cause water pressure in the appliance to rise, damaging your plumbing systems and discharging water.

A boiler expansion tank prevents this problem by yielding water the space it needs to expand when heated.

You should install or replace a boiler expansion tank if you notice a sudden thump sound in your plumbing after turning off your faucet. This noise indicates hydraulic shock in your boiler system, which can lead to discharge.

Where should the expansion tank be installed on a boiler? The answer to this question depends on several factors.

2. Steel Expansion Tanks

Steel expansion tanks are common in older properties. These do not come with a diaphragm. 

A diaphragm is a component that separates the tank into two sections. One section allows water to escape, while the other regulates water pressure. Since a steel tank combines these two sections into a single unit — allowing water and air to touch — it can cause rusting or corrosion to develop over time.

Steel expansion tanks also have pressure gauges that allow you to monitor the tank during operation. 

We can install your steel expansion tank directly above your boiler via a tee-fitting in the cold water pipe. The attachments you use will depend on the size and age of your appliance. In most cases, you can secure a copper pipe to an adapter and install the steel tank vertically above the water heater.

3. Bladder Expansion Tanks

In contrast with a steel expansion tank, a bladder expansion tank does include a diaphragm. Consequently, the water moving in and out of the boiler does not connect with air during transit. Bladder expansion tanks typically require less maintenance and last longer than steel tanks because the risk of corrosion is low.

Like the steel expansion tank, you can install these devices eighteen inches above your boiler. Sometimes, it’s practical to install an additional valve between connectors. This method makes removing and replacing a bladder expansion tank easy if it sustains damage.

4. Assessing the Tank

You should always inspect your expansion tank thoroughly before attempting an installation. Our contractors often see tanks with surface damage — pitting, cracks, etc. In such cases, an expansion tank installation could cause significant damage to your plumbing and compromise the cleanliness and temperature of your water supply.

A boiler expansion tank must undergo a pre-charge corresponding to the system fill pressure of your appliance. Most expansion tanks have a default pre-charge of between 10-15 pound-force per square inch.

Once the pre-charge is complete, you must replace the seal on the tank to keep a consistent air pressure reading during operation. We are pros at the pre-installation process and understand how challenging this step can be if you lack experience.

5. Installing the Tank

After your tank has an adequate charge, you can begin the fitting process to your water heater. First, connect it to the appropriate couplings. Ensure that water does not leak around the installation. 

If you find water filling the tank before it is secure, you must drain it and start the process over. 

You must always install an expansion tank on the receiving side of the warm-water circulator. You can find this component at the lowest end of the water line. Tighten the adapters and pressurize the water heater.

If you notice any discharge after pressurizing the heater, turn off the system and repair or replace the faulty expansion tank or adapter. Discharge indicates that the pressure in the tank will continue to drop, effectively making it useless. A leak may also suggest that your expansion tank is too small for your boiler or has an inadequate charge.

Where should the expansion tank be installed on a boiler if there is not enough space above the appliance? Don’t crowd your water heater with clutter or items that prevent you from installing the tank on the cold-water pipe. We can help you replace your boiler if your current appliance is not the correct size for your property. 

6. Post-Installation Inspection 

Inspect your expansion tank regularly. This practice helps you monitor water pressure and identify any leaks before they reduce the system’s performance. If you aren’t sure if your expansion tank is in the correct place, you can always call a professional plumber like ours to inspect it.

Our Boiler Repair Service

We don’t recommend trying to install a boiler expansion tank without experience. Calling our crew at Professional Services is the best way to ensure that your plumbing system performs efficiently. 

We will respond to your requests quickly and recommend the best products for your boiler or water heater. Our friendly contractors will explain how you can protect your appliance year-round and what to do if you notice leaks or damage. 

Enjoy outstanding communication and competitive pricing from our team during every interaction.

Contact Us

As a homeowner, you should understand how your plumbing system works. Our team is ready to provide the boiler facts you need when you call.

Where should the expansion tank be installed on a boiler? Learn more from our HVAC technicians at Professional Services. Schedule a consultation in Port Washington or the surrounding areas at 262-218-2636.