TO PROPERLY SIZE A WATTS SERIES ETX, ETSX, ETA or ET-RA NON-POTABLE WATER EXPANSION TANK: The set pressure of the boiler fill valve. 12psi Air Charge is Standard. The set pressure of the relief valve. NOTE: The lowest setting of the aquastat. NOTE: The maximum setting of the aquastat. MAX.Oct 18, 2023 · Water heater expansion tanks are not terribly expensive. But high-end models can be a bit pricier. Expect to pay anywhere from $40 to $200, or about $120 on average, for a water heater expansion tank. The price varies based on the tank size. On average, residential homes with 40- to 50-gallon water heaters use a 2-gallon water heater expansion ... Expansion Tanks on the How-It-Works series.Expansion tanks are critical components to your Plumbing and Hydronic Heating systems because they prevent your pu...Apr 11, 2014 · Expansion Tanks on the How-It-Works series.Expansion tanks are critical components to your Plumbing and Hydronic Heating systems because they prevent your pu... Steel-Type Expansion Tank maintenance should include: Test the level in the tank to ensure it is not waterlogged or overfilled. Additionally, this can cause problems with the loop and cause the pressure relief valve to vent unnecessarily. Check the tank for rust and corrosion. Lastly, ensure tanks are properly mounted and installed at the ... Call or text 888-757-4774. Amtrol 141N43 - THERM-X-TROL ST-12 Expansion Tank- Amtrol ST-12 (Therm-X-Trol) is a water heater expansion tank, designed for use in domestic hot water heating systems to eliminate the potential hazards of water expansion. Water heater expansion tank is commonly installed in a domestic hot water system …Expansion Tank Mounting Bracket for Hot Water Heater,Thermal Expansion Tank Holder with 2 Earthquake Straps,Support 5-Gallon Hot Water Tanks up to 13 inches in Diameter-1 Set. 4.8 out of 5 stars. 5. 50+ bought in past month. $16.99 $ 16. 99. 5% coupon applied at checkout Save 5% with coupon.5 days ago · Remove the cap to the valve stem on expansion tank and attach a tire pressure gauge. The pressure should be above 75 psi. If there is no air pressure within the tank, the expansion tank has failed. You will need to replace it with a new one. If there is pressure inside the tank, you'll need to check the water pressure. VEVOR Electric Mini-Tank Water Heater, 2.5-Gallon Tank Hot Water Boiler Storage, 1400W Power, Safety Temperature Pressure Valve Easy Install, for Kichen Bathroom Restaurant, Shelf Wall Floor Mounted 3.2 out of 5 stars 9 What is a water heater expansion tank? Water heater expansion tanks, also known as thermal expansion tanks, are devices that are attached to water heating systems to …A water heater expansion tank is a small tank that is attached to the water supply pipe of the heater. The expansion tank is designed to handle the thermal expansion of water as it heats up in the water heater, preventing excess water pressure. Speaking technically, there is a pressurised area within the expansion tank, sometimes called an air ...If the bladder extends beyond the normal movement, WessGuard ®. monitor will activate an audible LED alarm and energy management system to notify maintenance staff of a potential system issue. 101 Tank Street Greenwood, IN 46143. P: 317-888-9800 F: 317-865-7411 www.westank.com.Watts Hot Water Expansion Tank for Hydronic Baseboard Heater - Stainless Steel, 60psi, NPT Male Connection. Item #63726 | Model #0950162 ... An extremely important part of maintaining your expansion tank is checking the pressure. To check your expansion tank pressure, you should use a standard tire gauge and press it against the valve on the top of the tank. You can then adjust the pressure with a hand pump and raise the pressure as needed. If pressure is too high, simply press ... Factory pre-charged at 40 psi. Certified with cUPC and NSF 61 compliant. Brass air charging port with O-ring seal. 16-Gauge cold rolled steel shell. High quality coating prevents corrosion. 100% butyl rubber diaphragm lined with polypropylene. Maximum pressure of 150 psi. Maximum temperature rating of 200 degree F.About This Product. This expansion tank controls thermal expansion of water in open domestic hot water supply systems. It absorbs the increased volume of water generated by the hot water heating source. Its' pre-pressurized steel tank uses an expansion membrane to prevent air/water contact for long system life. Expansion - HVAC Tanks. Wessels manufactures three expansion tank designs: Compression, Bladder and Diaphragm. Each tank style has models that are either built in accordance with the ASME boiler and pressure vessel code or non-code. Tanks range in size from 2 to 10,000 gallons. Most of Wessels pressure vessels are designed using a pre ... Water storage tanks are the perfect solution for those looking to save some money on their water bills. Not only can you use it for your household, it can be used for animals, gard...The manufacturer’s instructions for the expansion tank can tell you how to do this. Install the tee fitting to the cold water supply line. Determine which end of the threaded connector on the expansion tank fits the tee fitting. Wrap the Teflon tape around the proper end; fit the tank connector to the tee fitting.The size needed for your expansion tank is determined by the size of your home's water heater. Expansion tanks are available in 2-gallon and 4.5-gallon sizes. A 2-gallon tank will be appropriate for water heaters up to 50 gallons. An adequately sized tank should have a volume that equals 2% to 5% of the water volume within the system. 0 / 0. AMTROL ST-12 (Therm-X-Trol) is a water heater expansion tank, designed for use in domestic hot water heating systems to eliminate the potential hazards of water expansion. Water heater expansion tank is commonly installed in a domestic hot water system that contains a backflow preventer, a check valve or a pressure reducing valve. To maintain a constant pressure, an expansion vessel is installed to contain the increase in the water volume as it expands as it heats up. The expansion vessel is divided into two compartments separated by a diaphragm. There is water on one side and air on the other side. Initially the air pressure equals the system pressure. As water heats inside the water heater and exceeds the capacity of the tank, the overflow rushes into the expansion tank. When an expansion tank is installed, the extra water volume automatically rushes into the tank. This lowers the water pressure inside your water heater to safe levels, protecting your tank (and other water appliances) from ... Jan 19, 2023 · How to Safely Remove an Old Water Heater: A Step-by-Step Guide. Jan 29, 2024. Removing an old water heater might seem daunting, but with the right approach, it can be done safely and efficiently. In this guide, we'll walk you through the process step-by-step, as explained by Steve from Fast Water Heater Company. Step 1: Drain the Water Heater... Step 5: Find the cold water supply. The expansion tank is usually connected to the cold water supply, so you need to determine which pipes are cold water supply. Step 6: Install your expansion tank. Hang the expansion tank above the cold water supply. Make sure that it can enter through the horizontal part and the water heater.Over six decades later, Extrol is still the world's leading expansion. From the Manufacturer. Amtrol Inc. designed and patented the first Extrol diaphragm expansion tank in 1954 to control system pressure and help reduce energy consumption in heating and chilled water systems. Over six decades later, Extrol is still the world's leading … The design is simple: create a true flow-through configuration. Wessels manufactures expansion tank products built in accordance with the ASME boiler and pressure vessel code. Wessels Full-Flow Bladder Tanks feature: Butyl bladder material –does not support nutrients found on natural rubber. Water circulation through the tank –every cycle ... Well water pressure tanks are connected to water wells and perform several vital functions in water supply systems. Here’s what you need to know about well water pressure tanks. A ...With the tank mounted, we can add inlet and outlet piping: Cut a short length of PEX and install an elbow fitting to the tank inlet. Run PEX from the elbow to a tee installed on the cold water supply. Repeat for the hot water outlet line. Secure all crimp rings and check for leaks. Use red PEX for hot and blue for cold.Hot water from a tap or shower head has become a main staple of the modern home. The ability to turn on the hot water tap and almost instantly obtain hot water is a feature of most...It should be installed after the anti-thermosyphon loop, at the highest point in the piping, and before connection to the tank. Pressure gauge. This is to verify the system pressure at the tank. Tank isolation valve. An isolation valve is necessary to service the tank without having to drain the entire system. It should be a lock-shield type to ...Air Blockage. Air is vital inside the hot water system of your expansion tank. If the air gets trapped inside your expansion vessel may have hydronic airlock issues. This air blockage can lead to unwanted sounds. Apart from that, water will fail to go inside the pipes and heater because of this type of black.Apr 11, 2018 · Hydronic Hot Water Systems. This calculator covers the design and selection of a hydronic hot water expansion tank. The expansion tank is a part of an overall hot water system that often includes a hot water generator (fuel fired boiler), piping, valves/fittings, water treatment, hot water coils (air handling units and fan coil units) and hot water pump(s). Jan 19, 2022 · The expansion tank of a water heater is a minor yet vital component that safeguards your home from potential damage due to excess pressure in your water system. When the water heats up in various parts of your home, like the kitchen or bathroom, it expands and creates pressure. An expansion tank acts as a safety net, absorbing this excess water ... This is because the water meters come with check valves which create a closed-loop system. Check with your city's plumbing inspector to be sure of the ...Dec 1, 2016 ... The expansion tank is installed on the water supply pipe that supplies the water heater. Water expands as it is heated, and without the room to ...Typical Expansion Tank Sizes for a Cast Iron Radiator type typical residential heating system. For a 100 MBTUH boiler you'd use either an Amtrol Extrol #60 or an Amtrol Fill-Trol #111. For 125-150 MBTUH you'd use an Amtrol Extrol #90. For a 175-200 MBTUH boiler you'd use an Amtrol Extrol #SX30V.Water Heater Expansion Tank Cost Breakdown. The main factors that influence the cost of installing a hot water heater expansion tank are materials—including the size and type of tank you install—and labor. Size. Most smaller homes will need a 2-gallon expansion tank, which costs $40 to $60.Thermal Expansion Tanks. Designed for hydronic heating systems or potable hot water systems, the tank uses compressed air to maintain system pressures by accepting and expelling the changing volume of water as it heats and cools. Carbon Steel Construction With a Heavy Duty Butyl Fixed Diaphragm. 3.5 to 90 Gallon Capacity.Hot water tank piping diagrams are essential for designing and installing an efficient and reliable hot water system in any residential or commercial building. The heart of any hot... Corrosion resistant 18 gauge galavanized steel provides safe and secure installation. Supports large 5 gallon or small 2 gallon expansion tanks. The durable support base bears the weight of the expansion tank. Inclued nylon straps keep tank securely in place. Bracket slots allow use with any water heater seismic safety straps up to 1-3/4" wide. A water heater expansion tank is a small tank that is attached to the water supply pipe of the heater. The expansion tank is designed to handle the thermal expansion of water as it heats up in the water heater, preventing excess water pressure. Speaking technically, there is a pressurised area within the expansion tank, sometimes called an air ... Oct 18, 2023 · Water heater expansion tanks are not terribly expensive. But high-end models can be a bit pricier. Expect to pay anywhere from $40 to $200, or about $120 on average, for a water heater expansion tank. The price varies based on the tank size. On average, residential homes with 40- to 50-gallon water heaters use a 2-gallon water heater expansion ... Ask your do it yourself plumbing questions and get free answers as well as DIY information about faucets, toilets, pumps and water filters from plumbers at ... Expansion - HVAC Tanks. Wessels manufactures three expansion tank designs: Compression, Bladder and Diaphragm. Each tank style has models that are either built in accordance with the ASME boiler and pressure vessel code or non-code. Tanks range in size from 2 to 10,000 gallons. Most of Wessels pressure vessels are designed using a pre ... An expansion tank is used in a hydronic hot water system to accomplish three main tasks, (1) accommodate thermal expansion of the hot water, (2) maintain positive pressure at …TO PROPERLY SIZE A WATTS SERIES ETX, ETSX, ETA or ET-RA NON-POTABLE WATER EXPANSION TANK: The set pressure of the boiler fill valve. 12psi Air Charge is Standard. The set pressure of the relief valve. NOTE: The lowest setting of the aquastat. NOTE: The maximum setting of the aquastat. MAX.Propane is an essential fuel for many households, providing heat, hot water, and cooking. Refilling your propane tank can be a hassle, but it doesn’t have to be. With the right app...A standard fifty-gallon unit expands to fifty-two gallons when heated to 120 degrees Fahrenheit, causing the volume of expanded water to rise to dangerous levels. Without a place to accommodate the increased liquid, it pushes out on the hot-water tank’s valve, fittings, gaskets and spigots. Hot water heater tanks are not designed to expand so ...HoldRiteQuick Strap 13-Dia Stainless Steel Expansion Tank Mounting Bracket For 5-Gallons Expansion Tank Water Heater. 44. • Secures expansion tank to wall and takes weight load off pipes. • Galvanized and stainless steel construction. • …Hot Water Boiler Expansion Tanks. The ratio of water to the air inside the steel expansion tank is optimal at 2/3rds water to 1/3 air. Tanks not equipped with a site glass need an Airtrol fitting. Located on the bottom of the expansion tank is a fitting. It has an air bleeder on the bottom of it.Apr 20, 2008. #3. tank. An expansion tank will work no matter where it is installed in the system. Recommendations call for it to be in the cold water line adjacent to the water heater, and after the shut off valve. These requirements are to insure that the tank does its thing even under unusual conditions.A water heater expansion tank is a small tank that is attached to the water supply pipe of the heater. The expansion tank is designed to handle the thermal expansion of water as it heats up in the water heater, preventing excess water pressure. Speaking technically, there is a pressurised area within the expansion tank, sometimes called an air ...Apr 20, 2008. #3. tank. An expansion tank will work no matter where it is installed in the system. Recommendations call for it to be in the cold water line adjacent to the water heater, and after the shut off valve. These requirements are to insure that the tank does its thing even under unusual conditions. Step 4: Install the Expansion Tank. Place the unit above the pipe that supplies cool water to make it close to the heater. Mark a spot on the wall and drill some holes for the mounting pipes. Screw-in the expansion tank and attach the cold water supply line. Jan 16, 2007 · List Price: $78.40. Metal. Made in USA. Accepts expanded water caused by thermal expansion. Returns water to the system when hot water is used. Prevents the relief valve from going off. Inline thermal expansion tank. Accepts expanded water caused by thermal expansion. Show more. Water Heater Expansion Tanks. Price. to. Go. $40 - $50. $50 - $100. Expert Installation Available $ 41. 87 (830) Everbilt. 2 gal. Thermal Expansion Tank. Add to Cart. Compare. ... Everbilt. 4.5 gal. Thermal Expansion Tank. Add to Cart. Compare. 0/0. Related Searches. hot water tank. pressure tank. expansion tank. watts water heater expansion ...Well water pressure tanks are connected to water wells and perform several vital functions in water supply systems. Here’s what you need to know about well water pressure tanks. A ...About This Product. This expansion tank controls thermal expansion of water in open domestic hot water supply systems. It absorbs the increased volume of water generated by the hot water heating source. Its' pre-pressurized steel tank uses an expansion membrane to prevent air/water contact for long system life.With 0 psi on the water side of the tank, the tank’s air charge should be pressurized to the system’s anticipated fill pressure. In this case, 30 ft. times 0.5 = 15 psi, plus 2 lb. residual = 17 psi. Then, you must also adjust the pressure regulator to compensate for the additional pressure necessary to lift the column of water to the top ...Signs of Trouble with a Heating Boiler Expansion Tank. Expansion tanks on hot water heating systems can be divided roughly into two groups: Older type bladderless heating system expansion tanks (atmospheric expansion tanks) and; Newer type internal bladder-type expansion tanks such as those sold by Amtrol Inc.; The behavior, maintenance, … When water is heated, it expands due to a phenomenon known as thermal expansion. Expansion tanks are designed to safely absorb the excess water created and prevent relief valves from triggering. We offer a range of expansion tanks for potable and non-potable applications. The potable water expansion tank shall be installed in the cold water service pipe line on the supply side of the water heater (or water storage tank). IMPORTANT: This Watts thermal expansion tank sizing tool should be used as a general guide to sizing thermal expansion tanks. Sizing calculations are wholly dependent on user input and are ...My hot water tank has a Thermal Expansion Control Valve installed on the cold water intake line (rather than an expansion tank). In the past 2-3 days, I have noticed that there is a small amount of water constantly draining out of this Valve/Tube.Apr 11, 2018 · Hydronic Hot Water Systems. This calculator covers the design and selection of a hydronic hot water expansion tank. The expansion tank is a part of an overall hot water system that often includes a hot water generator (fuel fired boiler), piping, valves/fittings, water treatment, hot water coils (air handling units and fan coil units) and hot water pump(s). Feb 11, 2010 · Step 1 - Define Expansion Tank Recharge. An expansion tank is attached to your boiler heating system to reduce the event of overflow creeping into a home or other building. It is a pressurized tank. When water takes up too much space in the expansion tank it will cause the air pressure to change. Recharging an expansion tank is the act of ... DESIGN: This 2-gallon thermal expansion tank has a dimension of 12. 4-inches x 8. 3-inches and it's indicated for use in water heaters and boilers with a capacity of 30-gallons to 50-gallons. FACTORY PRECHARGED: The expansion tank is factory precharged at 40 psi, this setting can be adjusted during installation to match the water …HoldRite Quick Strap 13-Dia Stainless Steel Expansion Tank Mounting Bracket For 5-Gallons Expansion Tank Water Heater. EASTMAN Nevercold 3/4-in-Dia Brass Recirculating Pump System Universal Water Heater. Rinnai 5-in-Dia Plastic Vent Extension Tankless Gas Water Heater. HoldRite Quick Shed 24-Dia Steel Enclosure For 40 …Oct 18, 2019 ... In today's video, we talk about the importance of having an expansion tank installed on your water heater. These tanks are very helpful in ...Installing an expansion tank is well worth your time and money for the peace of mind it provides. Step 1: Make a Plan. At this point, you will have a plan as to how you are going to run a branch line off of your hot water tank cold water supply to the expansion tank. Sketch out a diagram and obtain the correct fittings.The expansion tank of a water heater is a minor yet vital component that safeguards your home from potential damage due to excess pressure in your water system. When the water heats up in various parts of your home, like the kitchen or bathroom, it expands and creates pressure. An expansion tank acts as a safety net, absorbing this …With 0 psi on the water side of the tank, the tank’s air charge should be pressurized to the system’s anticipated fill pressure. In this case, 30 ft. times 0.5 = 15 psi, plus 2 lb. residual = 17 psi. Then, you must also adjust the pressure regulator to compensate for the additional pressure necessary to lift the column of water to the top ...Mar 10, 2021 ... Generally speaking, you can expect an expansion tank to last roughly 7-10 years. Having said that, it's important to note that it's not uncommon ...About This Product. Built with heavy-duty butyl diaphragm system to absorb the expansion of water volume and help prevent dangerous pressure build-up. This Everbilt Expansion … The thermal expansion tanks are engineered to meet ASME standards, and are also available in non-code designs. Wessels thermal expansion tanks are offered in industry’s broadest range from 2 to 4,000 gallons and up to 250 PSI. Pressurized thermal expansion tanks differ from plain steel expansion tanks in that a flexible bladder or diaphragm ... In order to empty out your water tank, open the valve and either loosen it or remove the six-sided connector. Loosen any screws that hold this part in place with an adjustable wrench. If you do not drain the tank completely then it will not properly recharge. 4. Recharge the expansion tank.HoldRiteQuick Strap 13-Dia Stainless Steel Expansion Tank Mounting Bracket For 5-Gallons Expansion Tank Water Heater. 44. • Secures expansion tank to wall and takes weight load off pipes. • Galvanized and stainless steel construction. • …To maintain a constant pressure, an expansion vessel is installed to contain the increase in the water volume as it expands as it heats up. The expansion vessel is divided into two compartments separated by a diaphragm. There is water on one side and air on the other side. Initially the air pressure equals the system pressure.1.0 INTRODUCTION. An expansion tank is used in a chilled water system to accomplish three main tasks, (1) accommodate thermal expansion of the chilled water, (2) maintain positive pressure at all points in the system at all times and (3) maintain net positive suction head at the chilled water pump(s).An expansion tank is a small tank divided in two sections by a rubber diaphragm. One side is connected to the pipes of the heating system and contains water. The other side is dry and... Section 2.0: Overall Hydronic Hot Water System. This guide covers the design and selection of a hydronic hot water expansion tank. The expansion tank is a part of an overall hot water system that often includes a hot water generator (fuel fired boiler), piping, valves/fittings, water treatment, hot water coils (air handling units and fan coil units) and hot water pump(s).
Prepping to Install a Water Heater Expansion Tank. Start by sketching out your plan for how to install a water heater expansion tank. Create a diagram of how …. Transmission flush cost
The purpose of a Thermal Expansion Tank is to act as an overflow for the excess water created by the water heating, maintaining safe expansion pressure. The ... It prevents the water heater pressure relief valve from opening, saves energy and eliminates a potential safety hazard. It is commonly installed in a domestic hot water system that contains a backflow preventer, a check valve or a pressure reducing valve. Measures: 11 in. L x 7.9 in. W x 11 in. H with 2.1 Gal. tank size, 6 lbs. weight and 3/4 ... The potable water expansion tank shall be installed in the cold water service pipe line on the supply side of the water heater (or water storage tank). IMPORTANT: This Watts thermal expansion tank sizing tool should be used as a general guide to sizing thermal expansion tanks. Sizing calculations are wholly dependent on user input and are ...What is a water heater expansion tank? Water heater expansion tanks, also known as thermal expansion tanks, are devices that are attached to water heating systems to …Expansion tanks are installed on the cold water pipe above the water heater. Generally, expansion tanks are installed in an upright position. However, they can be installed inverted or on their side, provided it is strapped for support. A water heater expansion tank is a small air-filled tank that acts as an expansion chamber to control ...To maintain a constant pressure, an expansion vessel is installed to contain the increase in the water volume as it expands as it heats up. The expansion vessel is divided into two compartments separated by a diaphragm. There is water on one side and air on the other side. Initially the air pressure equals the system pressure.Hot water replacement is common in households, as they wear out over time. The general lifespan is eight to 12 years depending on location, manufacturer’s design and maintenance. I... Thermal Expansion Tanks & Thermal Expansion Control Valves for water heater systems. Water heater (hot water cylinder) expansion tanks such as the 2 1/2 gallon expansion tank shown here from Falcon Stainless, Inc., is sold by Amazon and is intended to accomodate expansion in potable water or domestic hot water supply heating systems. After installing, turn the set temperature on your water heater up from 120 degrees F to 140 degrees F. the Tank Booster then mixes cold water back in to reduce the temperature down to a safe 120 degrees F. by storing water at a higher temperature and mixing cold water in to reduce the temperature, you will double the amount of usable hot water ...Installing an expansion tank is well worth your time and money for the peace of mind it provides. Step 1: Make a Plan. At this point, you will have a plan as to how you are going to run a branch line off of your hot water tank cold water supply to the expansion tank. Sketch out a diagram and obtain the correct fittings.Call or text 888-757-4774. Amtrol 141N43 - THERM-X-TROL ST-12 Expansion Tank- Amtrol ST-12 (Therm-X-Trol) is a water heater expansion tank, designed for use in domestic hot water heating systems to eliminate the potential hazards of water expansion. Water heater expansion tank is commonly installed in a domestic hot water system …Installing a hot water heater expansion tank is a crucial step in ensuring the optimal functionality and longevity of your water heating system. Expansion tanks help to alleviate the pressure buildup that occurs within the water heater as the water heats up and expands. Without an expansion tank, this increased pressure can lead to a range of ...Oct 20, 2017 ... We install them on all our water heaters now (and mixing valves). The expansion tank does as its name suggests. It allows for expansion in the ...In order to empty out your water tank, open the valve and either loosen it or remove the six-sided connector. Loosen any screws that hold this part in place with an adjustable wrench. If you do not drain the tank completely then it will not properly recharge. 4. Recharge the expansion tank.Step 5 - Pressurize the Expansion Tank: With the water supply turned off, ensure the tank's pressure reading is zero. Use a bicycle tire pump to inflate the tank to around 12 psi or follow the manufacturer's instructions. ... Step 12 - Verify Hot Water: Once the system has heated up, open a hot water faucet and ensure a consistent flow of hot ...May 24, 2019 · The key concepts are: 1. Pressurizing the air side of the tank to equal the static pressure of the water at the expansion tank location and before adding water to the system. This prevents cold water from partially compressing the air in the tank. The diaphragm only begins to compress when the water temperature rises. 2. Apr 11, 2018 · Hydronic Hot Water Systems. This calculator covers the design and selection of a hydronic hot water expansion tank. The expansion tank is a part of an overall hot water system that often includes a hot water generator (fuel fired boiler), piping, valves/fittings, water treatment, hot water coils (air handling units and fan coil units) and hot water pump(s). The thermal expansion tanks are engineered to meet ASME standards, and are also available in non-code designs. Wessels thermal expansion tanks are offered in industry’s broadest range from 2 to 4,000 gallons and up to 250 PSI. Pressurized thermal expansion tanks differ from plain steel expansion tanks in that a flexible bladder or diaphragm ... An expansion tank or expansion vessel is a small tank used to protect closed water heating systems and domestic hot water systems from excessive pressure. The tank is partially filled with air, whose compressibility cushions shock caused by water hammer [citation needed] and absorbs excess water pressure caused by thermal expansion. [1] A water heater expansion tank is a small tank that is attached to the water supply pipe of the heater. The expansion tank is designed to handle the thermal expansion of water as it heats up in the water heater, preventing excess water pressure. Speaking technically, there is a pressurised area within the expansion tank, sometimes called an air ... This tank is atmospheric and is located at a height above the CCCW pump suction line to provide make-up to the system and also to act as a surge for expansion of the fluid in circulation due to temperature changes. The tank level is maintained by a supply of DM water. Sign in to download full-size image. Figure 9.12..