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What are Thermal Expansion Tanks?

Thermal Expansion Tanks Are Your Friend

 

Thermal Expansion Tanks

     What, might you ask, is a thermal expansion tank and why do I need one? Good question, considering a vast majority of the population has never heard of a thermal expansion tank and doesn’t have a clue as to why it’s suddenly so important to have one installed by their new hot water tank.

     Of all the options for an installation of a water heater, the number one topic of debate is the necessity of the Thermal Expansion Tank. There’s no question about it. An expansion tank should be installed with every water heater every time. So often the thought is, “ my old water heater never had one, so why do I all of a sudden need one now?”  It’s a simple matter of physics. Most people understand that when water is heated it expands. So, If water is expanding , where does this “extra” water go? The Expansion Tank. When sized right and installed correctly, it’s the expansion tank’s job to take on this “extra” water caused by thermal expansion. Thermal expansion tanks have a rubber bladder in them with an “air cushion” on one side and the other side connected to the water piping.  When thermal expansion occurs, the water presses against the bladder and compresses the air cushion on the other side of the bladder to allow for that “extra” water to expand into the thermal expansion tank. When someone opens a faucet the compressed air presses on the bladder in the other direction to push the excess water back into the plumbing system. This device sized, tuned, and installed correctly minimizes excess pressure caused when water expands from being heated.  Okay, so that’s the “what”. Now here’s the “why”.

     In the past, expansion tanks were not as necessary as they are today. Back then, when thermal expansion would occur it would push the expanding water back through the plumbing system and into the city main. Today’s plumbing systems are more sophisticated, utilizing controls and other devices for efficiency and comfort. This often creates what is called a “closed system”, which prevents the expanding water from traveling back in the opposite direction.  Many utilities have also been adding check valves to their water meters, so that once city water passes your meter it cannot flow back into the city supply. This makes your entire home a closed system.  Since all of these things could potentially play a part in your plumbing system, the water is essentially trapped in this closed system until someone opens a valve. Imagine what happens when the water is heated in this closed system. With nowhere to go the pressure begins to increase substantially as the water tries to expand. This pressure could go well above normal working pressure, and could exceed 150-psi (pounds per square inch) if it weren’t for the safety relief valve. This valve is designed to open and relieve pressure from the water heater when it goes above 150-psi, draining to the floor, then outside the building where it won’t cause water damage. A system without a working expansion tank can face potentially large swings in water pressure, taxing the glass lining of the water heater, and other plumbing fixtures and components throughout the house. It could potentially be a small disaster in waiting.

     The most common problem with expansion tanks is incorrect installation. Our technicians commonly run across expansion tanks that have failed prematurely and/or were installed incorrectly. Thermal expansion tanks must be properly sized, located, tuned, and checked annually during the annual water heater maintenance. A good installation will help maintain minimal pressure increase caused by thermal expansion, can reduce water hammer, and help protect plumbing components from strain. An incorrect installation can be as bad as having no expansion tank at all, and sometimes worse. Incorrect installation can be the cause of everything from high water bills and water hammer, to excessive wear on the water heater and plumbing fixtures.

     So, now you have it, your physics lesson in thermal dynamics for the day. Not only can you impress friends and scientists with your new found knowledge, you can converse more confidently with your plumber next time you have a hot water heater installed. And we hope when that time comes, you’re having that conversation with a technician from Verne and Ellsworth Hann. Feel free to converse with us at 216-932-9755.

What People Are Saying

  • Your company did an excellent job!  We really appreciated how quickly your crew worked in order to get our heat back on as soon as possible.  Everyone seemed very knowledgeable, professional and excellent in their work!

    - George O.( Cleveland Heights, Boiler Installation, January 2018 )
  • Thank you thank you!  For your amazing response and difficult repair – I really appreciate it!

    - Marianne P.( Aurora, Boiler Installation, December 2017 )
  • Bill carefully examined the old boiler and piping, checked all the radiators and came up with a replacement proposal.  He explained two issues with the old boiler that other contractors did not notice or did not care to explain.  The first was what’s causing the rust in the boiler and how he was going to minimize the issue in the new system.  The second was how he would re-pipe the kitchen loop so the kitchen wouldn’t be so cold.  Bill addressed each and every question I had.  Although we received four bids that were comparable, we chose Bill Hann’s company because he was knowledgeable, thoughtful and detailed.  The work was completed in two days by a great installer team.  They were on time, professional and courteous.  The new boiler and piping work nicely without any issues and we now have a comfortable kitchen to dine in.  I’d highly recommend them.

    - Brian B.( Shaker Heights, Boiler Installation, January 2018 )
  • I strongly recommend Verne & Ellsworth Hann without reservation.  Choosing the right boiler was important and proper installation was critical.  I was impressed with all aspects of the Verne & Ellsworth Hann organization.  Most importantly, Bill Hann earned my trust.  The installation team was excellent.  They were experienced.  They arrived precisely on time every day.  They explained every step of the process.  They worked as a team.  They treated my home with extreme care, as if it was their own.  The installation is a thing of beauty.  Every time I go into my basement I smile.  I now have a reliable, efficient system.  I don’t usually take the time to write recommendations, but in this case I am doing so because it is so well deserved.

     

    - Allen P.( Shaker Heights, Boiler Installation, December 2017 )
  • Boiler has performed like a champ!  Install is neat and clean. Instructions for next 3 months have been followed.  New stat works well!

    - John R.( Cleveland Heights, Boiler Installation, December 2017 )