1. Elbi Expansion Tank Installation Instructions

• POST a QUESTION or READ FAQs about heating system expansion tanks: their function, size, location, maintenance, and need for draining (on some models)

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1. Install the galvanized tee on top of the water heater. Next prepare the long nipple with plumber's tape on both ends. Prep the threads on the expansion tank with plumber's tape and a brush of pipe joint compound. Last is nipple on top of the tee. Only the end going into the tee needs plumber's.
2. This expansion tank is designed for operation on the inlet cold water line and is limited to a maximum working pressure of 150 pounds per square inch (psi). Figures 1 and 2 above show the correct valves and fittings that you will need to install your.

Installing a. Thermal Expansion Tank. Water expands when heated. A 50 gallon tank of cold water becomes about 52 gallons or more when the water is hot. Installing a. Thermal Expansion Tank. Follow the installation instructions that came with your Thermal. Expansion Tank. Connect the tank to the cold water line.

Hot water heating system expansion tank / compression tank installation, troubleshooting, repair:

How to identify, inspect, install, repair, or service heating boiler expansion tanks: here we explain the function of expansion tanks on hot water (hydronic) heating systems.

We discuss what happens if the expansion tank becomes waterlogged, how to drain a waterlogged expansion tank, and what sorts of expansion tanks, like the one shown at page top, should never become waterlogged.

We describe where the expansion tank may be found (sometimes in the attic!) and we illustrate different sorts of expansion tanks used over the history of hydronic heating in buildings. In this article series we provide a heating system expansion tank / compression tank Troubleshooting & Repair Guide that will address just about any problem traced to this heating system component.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Heating Boiler Expansion Tanks - Troubleshoot, Understand, Fix

The photo at page top shows a modern Extrol(R) bladder-type heating system expansion tank. At left over our client's head is a reddish tan steel heating boiler expansion tank (or compression tank in some texts).

In detailed articles listed at the end of this page our information on hot water heating system expansion tanks includes:

How to Drain an Expansion Tank - Troubleshooting & Repair Guide: Diagnostic Tests for Waterlogged Heating Boiler Expansion Tank - How to troubleshoot an internal-bladder type expansion tank or How to troubleshoot a traditional bladderless expansion tank or compression tank. How to diagnose trouble with internal bladder Extrol type expansion tanks - What goes wrong with bladderless expansion tanks - waterlogging & its causes

[Click to enlarge any image]

What is a Heating Boiler Expansion Tank & How Do Expansion Tanks Work

Heating boiler expansion tanks are metal tanks of varying sizes that are installed to absorb the initial pressure increase that occurs when the heating boiler system warms up.

Air molecules entrained in water inside the heating boiler itself as well as in the heating system piping, baseboards, or radiators, expand and thus cause an initial pressure increase in the heating system.

That pressure is increase is absorbed by allowing water from the heating system to squash or compress a reservoir of air inside the expansion tank - which is why some heating experts call our expansion tank a 'compression tank'.

Inside of a working expansion tank is a reserve space of air. In fact, when the heating boiler and system are cool, the traditional bladderless boiler expansion tank will contain mostly air.

Or in newer smaller internal bladder type expansion/compression tanks an internal rubber bladder keeps air separated from the heating system's water - avoiding rapid loss of air by absorption into the heating systems' water.

As the heating system warms up and as airentrained in the water raises system pressure, the increased pressure forces some of the heating system water into the expansion tank, squashing its air-charge into a smaller volume, thuspermitting the tank to absorb the initial increase in system pressure.

Technical note: the water and air inside the expansion tank will always share the same pressure, but since water is not (very) compressible and air is, the increase in pressure will squeeze the air down to a smaller volume.

That's why some heating system water can pass into the expansion tank.

If heating system pressures and/or temperatures exceed normal (for a residential heating boiler that would be a pressure above 30 psi or a temperature much above 200 °F) then the expansion tank is dismissed from duty and the pressure/temperature relief valve on the boiler will open to provide emergency relief.

What Happens if the Expansion / Compression Tank is Not Working?

The loss of air cushion in the expansion / compression tank means that at each heating-on cycle the system pressure can be too high, causing the temperature/pressure relief valve to spill.

See RELIEF VALVE LEAKS for a catalog of causes of TPR valve leaks.

Watch out: if you see water dripping or squirting out of the temperature/pressure relief valve on any vessel, such as a hydronic heating boiler, the situation is unsafe. The valve may be doing its job of relieving excessive pressure or temperature, but there is a risk that the valve becomes clogged by mineral deposits or crud left by the escaping water. A clogged TPR valve is no longer protecting the system from an explosion

See details at BLEVE EXPLOSIONS

A second problem with older expansion/compression tanks - those that do not use an internal bladder to keep water and air separate, is the loss of air out of the compression tank and into the heating system water. We won't like the result.

Why do we care about keeping air out of the heating system water?

Air in the hot water heating system can cause loss of heat: air in baseboards radiators keeps hot water out - they don't get hot. And air in hot water heating system piping can simply keep hot water from ever reaching the radiators or baseboards.

Details are at AIR-BOUND HEATING SYSTEMS

See HOT WATER PRESSURE EXPANSION RATE if you're feeling curious about the physics involved in the pressure increase as we heat up water,

How & Why do Expansion Tanks Get Waterlogged?

Loss of Air Charge in a Bladderless Steel Traditional Heating System Expansion Tank

In older hot water heating boiler expansion tanks that do not have an internal bladder to keep air and water separate, over time air in the expansion tank may become absorbed into the heating water.

Elbi Expansion Tank Installation Instructions

Air may also find its way via the heating water to other air bleeders or vents in the system.

As air is lost and water just stays in the expansion tank, the space and pressure cushion provided by air in the expansion tank gets too small, or is lost entirely.

There is no more air cushion to absorb initial pressure increases in the heating system during each heating boiler on-cycle.

Loss of Air Charge in an Internal-Bladder-Type Heating System Expansion Tank

In a modern internal-bladder type expansion tank use on heating systems it is not usually necessary to add air nor to change the tank pressure. There are however several sources of loss of the air charge and causes of water logging in an internal bladder-type expansion tank:

• Expansion tank bladder rupture: Occasionally the internal bladder of these tanks an rupture, leading rather quickly, perhaps in less than a single heating season, to a water-logged expansion tank tank. In that case the symptom may be observing that heating system pressure relief valve may spill or water may be found leaking out at the expansion tank's air pressure adjustment valve.
  See this field report: RELIEF VALVE LEAK DUE TO EXPANSION TANK that traces a leaky relief valve to a failed expansion vessel on a Cosmogas boiler.
• Expansion tank pinhole leak: occasionally a pinhole leak develops in the internal bladder of an expansion tank. We first received reports of this subtle failure from readers reporting on waterlogged water supply system pressure tanks.
  The pinhole leak is almost impossible to observe even if you cut apart the tank to remove and inspect the rubber tank bladder or diaphragm.
  Rather the symptom shows up as a slow loss of tank volume that can result in cyclic leaking at the heating systems TPR valve. Since other heating system problems such as water hammer can also cause sporadic TPR valve leaks or drips this defect can be hard to track down.
  On water supply system tanks we may observe an increase in the air pressure of the tank above its initial charge, measured at its pressure valve, even when there is no water pressure on the system.
  That's because water has leaked into the air space, reducing the available volume for air and thus permanently increasing the pressure therein. Remember from your gas laws that P1V1 = P2V2? If we reduce the air volume the pressure must increase.
• Expansion tank membrane permeability: Reader NJT, Holohan, and several other sources cited at REFERENCES note that a bladder-type hydronic heating expansion tank may lose air pressure at about 1 psi per year as air passes through the tank membrane and into the heating system's hot water.
  Considering that heating system pressures and temperatures are cycling constantly during the heating season, one may speculate that the unidirectional movement of air from the tank through its bladder and into the heating water would have to be occurring when system pressures are highest.

Boiler Expansion Tank Installation & Operation Manuals, Guides, Standards

Illustration: an example guide showing the location of two types of expansion tanks, excerpted from Amtrol's Extrol instructions from 2014, cited in detail below.

• AMTROL's EXTROL®, the FILL-TROL® [article, in-depth w/ more citations & documents for Amtrol Extrol expansion tanks used on heating systems]
• AMTROL, EXTROL® EXPANSION TANKS INSTALLATION & OPERATION INSTRUCTIONS [PDF] (2016) Models EX-15 - EX-90, Models SX-30V - SC-160V, Extrol Corporation, 1400 Division Road, West Warwick RI 02983, Tel: 401-884-6300, Website: www.amtrol.com, retrieved 2018/08/03, original source: https://www.amtrol.com/wp-content/uploads/2017/04/9015-941-10_16-Extrol-IO-w_InSight-Cap.pdf
• AMTROL EXTROL® EXPANSION TANKS IO INSTRUCTIONS [PDF] (2014) Models EX-15 - EX-90, Models SX-30V - SC-160V,
• AMTROL EXTROL® EXPANSION TANKS IO MANUAL [PDF] (2003) In-Line & SX-Series EXTROL Expansion Tank instructions, retrieved 2018/08/03, original source: https://www.sunsourceproducts.com/library/documents/Amtrol-Extrol-InstallOperation.pdf
• AMTROL FILL-TROL® EXPANSTION TANK IO MANUAL [PDF] (2014) Models FT-109 - FT-111, Amtrol, Inc., retrieved 2018/08/03, original source: http://www.amtrol.com/wp-content/uploads/2017/05/9015026_06_14_FillTrol_IO-1.pdf
  
  Excerpts from Amtrol's Fill-Trol Instructions: For Use In Closed Hydronic Systems Only
  FILL-TROL® is a combination of an EXTROL® expansion tank anda specially designed automatic pressure reducing valve. Together,they manage water expansion to provide satisfactory heating systemperformance.
  The EXTROL is pre-charged at the factory to 12 PSIG and is readyto install in most residential and light commercial systems withoutadjustment.
  The valve is designed to fill the system with water andautomatically shut off the flow when it reaches the precharge pressurein the tank. It will also restore the system to 12 PSIG if the pressuredrops below that point.
  The precharge may be changed to set thedesired fill pressure. Do not install on domestic water systems, or in open heating systems. Corrosion and tank failure may result.
  Use a Therm-X-Trol® or Therm-X-Span® for domestic water systems.
  Use a Radiant EXTROL® for radiant heating systems where air elimination equipment or barrier tubing is not used.
  
• ARMSTRONG L-SERIES BLADDER EXPANSION TANK IO MANUAL [PDF] (2003), Armstrong Pumps Inc., 93 East Ave., North Notawanda NY USA, 14120, Tel: 716-693-8813, Website: www.armstrongpumps.com
  or S.A. Armstrong Ltd., 23 Bertrand Ave. Toronto Ontario Canada M1L 2P3, Tel: 416-755-2291
  or Armstrong Pumps Ltd., Peartree Road, Stanway, Colchester, Essex United Kingdom CO3 0LP Tel: +44 (0) 1206 579491
  This tank uses a replacable internal tank bladder.
• ARMSTRONG L-SERIES BLADDER EXPANATION TANK MANUAL [PDF] (2000) top outlet, installation & operation instructions, includes instructions for changing the expansion tank's internal bladder. Armstrong fluid technology.com Op. Cit.
  
• Bell & Gossett AIRTROL® System Installation, Operating and Service Instructions, Bell & Gossett, 8200 N. Austin Ave., Morton Grove IL 60053, USA - Tel 847 966-3700 Fax 847 965-8379. Retrieved 8/9/2012, original source B&G, [copy on file as Airtrol_Installation_Manual.pdf linked in this reference]
• Bell & Gossett B&G PRESSURIZED EXPANSION TANKS (ASME) Series B, D, B-LA INSTRUCTION MANUAL [PDF] (2012) Bell & Gossett, Xylem Inc.8200 N. Austin AvenueMorton Grove, Illinois 60053USA Tel: (847) 966-3700Website: www.xyleminc.com/brands/bellgossett
• Extrol Corporation, 'Installation & Operation Instructions, Extrol (R) Hydronic Diaphragm Expansion Tanks In-Line & SX-Series', Extrol Corporation, 1400 Division Road, West Warwick RI 02983, Tel: 401-884-6300, Website: www.amtrol.com, retrieved 3/3/2014, original source http://www.amtrol.com/media/documents/extrol/9015183_3_11_EXTROL_IO.pdf
  
• HONEYWELL EXPANSION TANK TK300-XPS MANUAL [PDF] (2006), Honeywell International, Inc., 1985 Douglas Drive North, Golden Valley, MN 55422 USA
  or Honeywell Limited-Honeywell LimitÈe, 35 Dynamic Drive, Toronto, Ontario Canada M1V 4Z9
  Website: customer.honeywell.com
  
• TACO EXPANSION TANK MANUAL CA-SERIES [PDF] (2014), Taco, Inc., 1160 Cranston St., Cranston RI 02920 USA, Tel: 401-942-2800,
  or TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario Canada L5T 2B3 Tel: 905-564-9422
• TACO EXPANSTION TANK BAG REPLACEMENT INSTRUCTIONS CA-EXP Series [PDF[ (2015) Op. Cit. , retrieved 2018/08/03, original source: http://www.taco-hvac.com/uploads/FileLibrary/402-013.pdf
  Most Taco Expansion Tanks are available with either bladders or diaphragms so that water and air are permanently separated.
• TACO EXPANSION TANK MANUAL CBX [PDF] (2013), Op. Cit., retrieved 2018/08/03, original source: http://www.taco-hvac.com/uploads/FileLibrary/402-020.pdf
• TACO EXPANAION TANK CBX BLADDER REPLACEMENT INSTRUCTIONS [PDF] (2004), Op. Cit., retrieved 2018/08/03, original source: http://www.taco-hvac.com/uploads/FileLibrary/402-090CBXExTankRep.pdf
• TACO EXPANSION TANK CW INSTRUCTION SHEET [PDF] (2010), Op. Cit., retrieved 2018/08/03, original source: http://www.taco-hvac.com/uploads/FileLibrary/402-093.pdf
• TACO EXPANSION TANK CW EXP BLADDER REPLACEMENT INSTRUCTIONS [PDF] (2001), Op. Cit., retrieved 2018/08/03, original source: http://www.taco-hvac.com/uploads/FileLibrary/402-025.pdf
• TACO EXPANSION TANK CX INSTRUCTIONS [PDF] (2013), Op. Cit., retrieved 2018/08/03, original source: http://www.taco-hvac.com/uploads/FileLibrary/402-015.pdf
• TACO PS-Series EXPANSION TANKS are also available in plain-steel construction in a range of sizes.
  
• WATER WORKER EXPANSTION TANK INSTALLATION INSTRUCTIONS [PDF], Water Worker, Tel: 401-884-6300, Website: www.waterworkerdiy.com, sold at Lowes building supply stores, retrieved 2018/08/03, original source: http://pdf.lowes.com/installationguides/642031654595_install.pdf
  
• WATTS ET SERIES EXPANSION TANK INSTALLATION INSTRUCTIONS [PDF] (2008) Series ET, Models ET-15 - ET-160 (1/2' NPT for use with an air separator) & Model ET-90 (3/4' NPT) Watts Water Safety & Flow Control Products, 815 Chestnut St., No. Andover, MA 01845-6098 USA, Website: www.watts.com or Watts, 5435 North Service Rd., Burlington, ONT. L7L 5H7 Canada, Website: www.wattscanada.ca
  Excerpt:
  Watts ET Series may be installed in a tee or any other suitable tapping inthe heating system and can be installed in a vertical or horizontal position.
  CAUTION: The tank must be properly supported in horizontal applications.Max. temperature 210°F (99ºC),Max. working pressure 60 psi
• WATTS ET ETX EXPANSION TANK INSTALLATION INSTRUCTIONS [PDF] (2008) Series ETX, ETSX hot water heating system expansion tanks, Op. Cit.
  Excerpt:
  Series ETX may be installed in a tee or any other suitable tapping in the heating system and can be installed in a vertical or horizontal position. Series ETSX are floor models.
• See additional citations at REFERENCES
• Also see MANUALS & PARTS GUIDES - HVAC - home for manuals for HVAC equipment, all brands.

Research on permeability of rubber used in internal bladder-type heating system compression tanks or expansion tanks

• Bodell, Bruce R. 'Distillation of saline water using silicone rubber membrane.' U.S. Patent 3,361,645, issued January 2, 1968.
• Ciesielski, Andrew. An introduction to rubber technology. iSmithers Rapra Publishing, 1999.
• Fuller, James, and David M. Stedham. 'Expansion tank with a predictive sensor.' U.S. Patent 8,633,825, issued January 21, 2014.
• Martinello, Ermanno, and Mark Weih. 'Membrane coating for a water pressurization Bladder.' U.S. Patent Application 12/498,128, filed July 6, 2009.
• Stern, S. A., F. J. Onorato, and Charles Libove. 'The permeation of gases through hollow silicone rubber fibers: Effect of fiber elasticity on gas permeability.' AIChE Journal 23, no. 4 (1977): 567-578.
• Terashita, Fumihiro, Shingo Takagi, Shinzo Kohjiya, and Yasutoshi Naito. 'Airtight butyl rubber under high pressures in the storage tank of CAES‐G/T system power plant.' Journal of applied polymer science 95, no. 1 (2005): 173-177.

Expansion Tank Sizing Procedures

This article has moved to EXPANSION TANK SIZING GUIDE

Amtrol's Adapted Extrol®, the Fill-Trol® Diaphragm-Type Expansion Tank

This article section has been moved: see AMTROL's EXTROL®, the FILL-TROL®

Signs of Trouble with a Heating Boiler Expansion Tank

This content has moved to EXPANSION TANK DIAGNOSIS

How to Drain & Re-Charge the Air Needed in a Heating Boiler Expansion Tank, step by step

This topic has moved to EXPANSION TANK DRAIN & AIR RE-CHARGE

Can't Find the Expansion Tank?

This article section has been moved to FIND the EXPANSION TANK

Other Leaks Into Boilers Can Cause Over-Pressure in the Boiler & Relief Valve Leaks

Reader Question: I drained the expansion tank but the system pressure is still too high; high radiators in the house are cold & the relief valve spills

We moved this discussion to LEAKS into the BOILER CAUSE RELIEF VALVE LEAKS

Pressure Settings for Expansion Tanks

Moved to EXPANSION TANK PRESSURE ADJUSTMENT

Service Procedure Using a Pump Damages Expansion Tank Internal Bladders

This discussion has moved to BOILER DRAIN DAMAGES EXPANSION TANK

See HOT WATER TANKS, INDIRECT FIRED for details about that type of domestic hot water heater.

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Technical Reviewers & References

• Holohan, Dan, 'Why compression tanks waterlog', HeatingHelp.com (June 2014) - retrieved 19 March 2015, original source: https://heatinghelp.com/systems-help-center/why-compression-tanks-waterlog/
• Etherton, Mark (contractor), 'Expansion Tanks 101: the facts and myths', Contractor Magazine, contractormag.com, (March 2000), retrieved 19 March 2015, original source: http://contractormag.com/hydronics/cm_column_75
• [4] B&G / ITT Reducing Valves, Instruction Manual V55999: Reducing Valves Installation, Operation, & Service Instructions, Bell & Gossett Air Separators and other heating system components, Bell & Gossett, 8200 N. Austin Ave., Morton Grove IL 60053, USA - Tel 847 966-3700 Fax 847 965-8379. Original source www.bellgossett.com/literature/files/610.pdf
• Domestic and Commercial Oil Burners, Charles H. Burkhardt, McGraw Hill Book Company, New York 3rd Ed 1969.
• 'Residential Hydronic (circulating hot water) Heating Systems', Instructional Technologies Institute, Inc., 145 'D' Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
• Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals,
• Boilers, Boiler Conversions, James E. Brumbaugh, ISBN 0-672-23389-4 (v. 1) Volume II, Oil, Gas, and Coal Burners, Controls, Ducts, Piping, Valves, James E. Brumbaugh, ISBN 0-672-23390-7 (v. 2) Volume III, Radiant Heating, Water Heaters, Ventilation, Air Conditioning, Heat Pumps, Air Cleaners, James E. Brumbaugh, ISBN 0-672-23383-5 (v. 3) or ISBN 0-672-23380-0 (set) Special Sales Director, Macmillan Publishing Co., 866 Third Ave., New York, NY 10022. Macmillan Publishing Co., NY
• Installation Guide for Residential Hydronic Heating Systems
• Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922
• ...

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Related Articles

• 1 Install a Tankless Water Heater Pressure Relief Valve
• 2 Replace Corroded Couplings for Hot Water Tanks
• 3 Test Household Water Pressure
• 4 Fix a Copper Pipe Leak Without Welding

Before new plumbing regulations came into existence, excess water from water heaters flowed back into the municipal water supply, causing contamination. One solution was to fit a backflow valve on the heater outlet. However, added pressure overstressed the tank, causing an explosion hazard. Changes in municipal regulations now call for an expansion tank to be fitted to water heaters. These tanks are divided by a rubber membrane supported by compressed air, with sufficient space above the membrane to absorb the overflow. With the latest breakthroughs in plumbing technology, you can save money by installing a pressure tank yourself.

Household Pressure

Obtain a suitable thermal expansion tank based on the size of your water heater. Read the pressure requirement on the side of the tank; this is usually between 40 and 60 psi. Establish the household’s static pressure by attaching a pressure gauge to a threaded faucet such as a washing machine inlet or garden standpipe. Turn off all faucets and relevant appliances to get a reading of the household’s static water pressure. If it is above 60 psi or below the recommended pressure printed on the expansion tank, adjust the household's water pressure reducing valve. This is a small component fitted with a bell-shaped housing between the water meter and main household plumbing. Undo the locknut below the hex screw protruding from the top of the bell-shaped housing. Ask a friend to monitor the pressure gauge while calling you on his cell phone. Turn the adjusting screw clockwise with an adjustable wrench to Increase the pressure; counterclockwise to reduce pressure. When the pressure reaches the expansion tank’s recommended setting, hold the adjusting screw steady and tighten the locknut with a second adjustable wrench.

Tank Pressure

Check the pressure inside the expansion tank with a tire-pressure gauge pressed onto the Schrader valve on the bottom of the tank. If the reading is high, bleed off some of the pressure. If it is below the recommended pressure, attach a hand pump to the Schrader valve and pump in more air until the reading on the tire gauge coincides with the static pressure in your home. Do not use an air compressor as it may rupture the rubber bellows inside the tank.

Saddle Clamp

Locate the household water supply shutoff valve on the house side of the pipe leading from your water meter. Turn the handle all the way to shut off the water, then open a bathroom or kitchen faucet until it stops dripping, to relieve any water pressure. Use a saddle valve to provide a T-coupling attachment point on the pipe without cutting the tubing or using solder. Undo the clamp bolts, remove the upper half of the clamp and position the saddle valve on the tubing with the outlet pointing downward. Ensure the rubber gasket on the lower half of the valve is seated properly. Slide the saddle valve sideways to allow sufficient clearance for the expansion tank to fit between the valve and the water heater. Replace the top half of the clamp and tighten the clamp bolts fairly securely with an adjustable wrench; do not collapse the tubing by overtightening the clamp. Screw the piercing handle on the side of the valve clockwise all the way until the sharpened point penetrates the copper tubing. Undo the piercing handle to the fully open position. With the tank pointing downward, this configuration will support its weight without stressing the copper tube.

Installation

Wrap a short piece of Teflon tape tightly around the expansion tank's connecting thread. Lift the tank and screw it clockwise onto the saddle valve until the threads are tight. Open the household water shutoff valve and check for leaks. If water drips from the base of the piercing handle shaft, tighten its connecting union carefully until it stops dripping. Alternatively, if water seeps out of the clamp, tighten the clamp screws another quarter turn. Open the hot water faucet farthest away from the tank to bleed off any air bubbles trapped in the pipes.

About the Author

After graduating from the University of the Witwatersrand and qualifying as an aircraft engineer, Ian Kelly joined a Kitchen remodeling company and qualified as a Certified Kitchen Designer (CKD). Kelly then established an organization specializing in home improvement, including repair and maintenance of household appliances, garden equipment and lawn mowers.

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