Do I need a thermal expansion tank? - Let's do an experiment! 

When learning about this expansion tank, there shouldn't be any other video than this one. You showed thermal expansion visually and with a pressure gauge. You showed us the bladder inside and how it works with an increase in pressure. You can't show any more about this topic. Nice job man

The reason you now need a thermal expansion tank is because public water supplies used to be "open." Basically just a pipe from the street to your house. When water in the water heater expanded, it could easily flow back into the public water supply. However, there were instances of stuff getting into the water supply so today most water meters have a "check valve" that prevents this from happening. So you need a thermal expansion tank nowadays. If you don't have one, among other things, the water heater tank will balloon out when the water pressure is high and then back in when it's not. This in and out tank expansion cracks the glass lining of the tank causing it to corrode and leak prematurely. So thermal expansion tanks make water heaters last longer. Also the greatly increased water pressure from thermal expansion often damages piping and valves on washing machines, dishwashers, ice makers, etc. and can cause pipe connections to leak. The temperature and pressure relief valve will open if the pressure gets too high, but if that happens frequently, the T&P safety valve can get clogged with sediment and may not work when you really need it to. To check if you need a thermal expansion tank (or to test if the one you have is working), put a water pressure gauge anywhere on the cold water side of your plumbing system, then use a lot of hot water (so the tank will fill with cold) and watch the pressure gauge as the cold water is heated. If the pressure does not rise during a heating cycle, either you don't need a thermal expansion tank or the one you have is working. However, utilities come around and replace meters all the time so you may not need one today and could need one tomorrow. My neighbor (who, ironically, works for the water company) got her meter replaced (while at work). She had no expansion tank. A few days later, a plastic fitting under a bathroom sink couldn't take the higher pressure and her house was flooded (took six months to repair). Finally, it's a good idea to get some leak detectors (they look a lot like smoke detectors) and put under sinks, near the HVAC system--anywhere water might leak. Has saved my house several times...

I bought this water heater ru-vid.comUgkx8G49mV71sAzUl9shXyLW-r3XgHH9EVh1 for use in my bus conversion. I installed it under my kitchen sink and it is fed by a high efficiency on-demand LP water heater. It is both a backup hot water source as well as a water saving device since we have hot water on demand rather than having to wait for the gas on demand water heater to finish its ignition cycle. I decided on this water heater due to the fact that it only draws 1300watts when it's ON instead of the 1500 watts that most Water heaters this size draw. In an RV a couple hundred watts can be a big deal. With very low standby losses, I don't have to worry about excessive power consumption. When propane is not available for our gas water heater, in conjunction with our low flow shower head there is enough hot water available to shower, albeit we won't be taking "hotel showers." Also very happy with the recovery rate of this water heater. Granted, it is quite small, but it does exactly what we need it to do.

This is one of the best documentary on expansion tank.

HVAC guy here. This video was awesome. Thank you!

I used to live in the Midwest, now I’m in East Phoenix. Almost all residential water distribution is above ground out here. I can remember when I’d only been out here a few months, I was home in the middle of the day and tried to take a shower when it was ~115° outside. On full cold the water was just shy of scalding, 120°+. It was at the extreme upper limit of tolerable for me - and then only for exceedingly short periods. So yeah, no doing laundry or showering in the middle of the day unless you’ve got some MacGyver projects already in flight. Another piece of trivia showing Arizona is not a suitable environment for humans: there’s a phenomenon of people in motorcycle/traffic accidents, or pedestrians struck by vehicles, wherein the victim ends up on the blacktop and suffering more serious injuries from having laid or fallen on the ground than from the collision which threw them to the ground. Stay where there’s trees & grass & seasons & most of the people on the interstate aren’t from LA. Where using your turn signal isn’t considered a sign of weakness. I’ve wandered off topic and into a nostalgic rant, my apologies. Enjoy your content. Cheers!

Been in the plumbing industry for 20+ years. The way this video is put together is PERFECT, definitely knows plumbing very well. Just make sure to run video at 1.25 speed so that it feels normal. 😁

Thank you so much for posting this video. About two years ago, our small town replaced the old water meters. Immediately after this, we noticed water on the floor of our basement at the bottom of our tank water heater, clearly from the PRV. We were having to empty a large plastic Folger's coffee container every 2-3 days. We were also experiencing a short blast of high pressure water whenever we would turn on a faucet. Uneducated about this particular area of plumbing, I was still smart enough to know that none of this was right....at all. It took several days of internet investigation and calls to Town Hall to find out that the new meters changed our water supply to a closed system. Long story short.....I have a Watts thermal expansion tank (honestly...because that's the label on your tanks...lol) arriving this weekend. And I've already installed a secondary inline PRV. I just didn't trust the PRV on the tank for some reason. Again, we cannot thank you enough! You can't imagine the stress you have relieved in this household. This video should be the Gold Standard for all educational videos posted! You truly did a fantastic job. We have subscribed and clicked the bell......you've got us for life!! ❤😊❤

I am a retired home inspector and never received this type of training. When I came across these tanks I only knew to check the pressure on both the water heater and the tank based on training myself through compairson between different homes. This is an excellent video and a valuable training aid to all...

I'm over here wondering why our public schools don't do what you just did. You sir are a legend. Keep it up!!

This should be a required part of the training every new plumber must receive. You did an outstanding job presenting this information in a way that every home owner, building inspector and tradesman will understand and remember. I’m really impressed!

What a GREAT demonstration! You should mention that it is code in many locations to put those in. This is because municipalities are putting in backflow preventers at residential meters and the water has nowhere to go. With no backflow prevention the water simply goes back out into the main. We know that, but people that don't know what expansion tanks are don't.

No one could have done a more thorough and effective job of explaining all this as you did. I learned so much. Great job!

As a retired plumber of 48 years, I used to be puzzled at how many people did not know basic physics. Now I realize my Earth Science teacher in 9th grade was a jewel, Thanks Mr. Rice, Central High, Cheyenne Wyo. 1969

Greetings from the Gambia🇬🇲. Im a plumber in my 5th year apprenticeship. You can follow nice meeting my fellow plumbers😊❤

Owned many homes for decades, never needed an expansion tank. Never had a problem

Thanks for taking your time to show us this. Excellent work!

I am on a municipal water system with no backflow preventer installed. Now I know why an expansion tank was not installed on my water system.👍🏻

Yes my friend , you did wonderful job for mechsnical contractor

Very good video explaining the purpose and how the thermal expansion work. My only "silly" suggestion is to chance "water creation" to "more volume" . The mass of water doesn't change but its volume. Thank you

One other thing you should add to your discussion is the potential effect of added pressure to any weak pipe connection in the system, for instance a buried elbow hidden inside a living space wall. For anyone still using Polybutylene pipes, a thermal expansion tank could mean significant added life to their water supply system. I did an in depth study of thermal expansion tanks a few years ago and I now have them both at my home and my vacation home as well. Thanks for the video, the visualization of the water expansion and the baloon in the bottle were highly instructive, great lateral thinking on your part.

I am a retired marine engineer and was aware of how an expansion tank works because we had similar but much larger systems on boar made by a company called Newpress. I watched your video just to see how good an explanation you were going to give an I must admit you did an excellent job of explaining how the system works and why you need expansion tanks in a sealed system. The only thing I would add, if I may, is the reason why your expansion tank doesn’t collapse like the water bottle did. Thanks that was a very well explained tutorial with excellent demonstrations. Thank you.

All true if the house has a PRV or some form of backflow prevention (i.e., check-valve, not all do!) as that won't allow water to expand back into the system, causing the excess pressure. If the house doesn't have a a PRV or check valve an expansion tank is NOT needed. My home has neither a PRV nor a tank. That being said, good explanation of why many homes DO need a tank!

I wish my plumber had watched this. Instead I put up with 13 yrs of a dripping T/P valve, then finally installed one myself. Thanks for educating us all!

Another big thing to know is whether your incoming water to your house has a one way check valve at the water meter. If there is one you are defiently going to need an expansion tank. In my area there is no check valves for the incoming water supply. So an expansion tank is not required. Great demonstration.

I truly appreciate the amount of time and effort put into this video, setting up the visuals and also editing it all together.. with incredible quality both audio and video. Very hard to come by videos this great today.

Loved your comment about AZ cold water temp... I'm in Tucson and during this summer (2023) there were a couple weeks where the cold water was warm/hot enough so that my showers didn't need any hot water...

I've been in the hvac business for 20 yrs and had boilers with hot water element fail every 2 yrs leak and now it makes perfect sense thank you for your detailed info and dedication 😮

Can you learn everything about everything then teach it all to us just like this? Great job, appreciate the time and effort you put in this video for us.

Seeing the demonstrations helps me understand the concept tremendously! Nice job 👍

If you are responsible for the plumbing setup in your video... 👏👏👏! Beautifully done!

great representation of a expansion tank, you made it all make sense. Great video, thanks for your time!

Fantastic and comprehensive look at current plumbing best-practices. Definitely learned a thing or two for my home. Bravo!

Wow! What a great lecture and demo! Thank you.

I've been a plumber for 40+ years. I think you nailed it.

Great, great explanation of how expansion tanks work. Love your video and how detailed it is explained. Clearly visualize with the gauges and simulated scenario in real time. Thanks for share your knowledge and experience. Today I learned more!! 👏👏

Wow! By far the best video on expansion tanks on the web!!! Great job thank you very much for doing this and sharing

I'm in St. Louis. Customers, especially older ones, are all so skeptical of "that blue ball thing that you put on my water heater". I've developed a pretty good understanding of thermal expansion and I feel like I'm able to explain it pretty well, but this video is a game changer. Thanks for putting in the time.

Perfect interpretation of how important these tanks truly are.

One of the best no-bs demonstrations I've watched on youtube to date! Very well done, thank you!

I think you about covered every angle on this ! I installed a pressure reducing valve on our system in addition to the expansion tank. The PRV definitely closes to system but I believe very essential to reduce pressure to fixtures to 50 psi max. They will last longer. Our input pressure is over 80 psi at the meter . I also think that the expansion tank may prolong the tank life by retinue the amount of expansion/contraction inside it. For those who think 80 plus psi is nice, be aware that most well pumps only deliver within a 30-50 psi range.

This has been an excellent video. Great explanations and demonstrations. I have always wondered why expansion tanks became common on plumbing systems. Well done!

Great video. There is no "more water". It is expanded water. As you show, if the pressure gets high enough to be a danger, the pressure relief valve opens and reduces the pressure. At best, expansion tanks save you this wasted water. And there is also a second safety valve that pops on water heater should the pressure relief value fail. One would think water heater makers would include an expansion tank inside the water heater, but they are cheap. I bet they could sell a lot if they did that though since it save installation time. Also, the pressure does not keep building and building until the water heater explodes, provided the thermostat is working. It shuts off the heating and the pressure stops increasing. To make the water heater explode, you have to disable the pressure relief valve, block the emergency pressure plug, and disable the thermostat. Doing that is crazy since it make the water heater a bomb.

The best video explaining thermal expansion tanks and water heating functions! Excellent work!

This might be the best home systems video I’ve ever seen. Amazing demonstration, thank you.

To add a few things that might help those who aren’t quite aware of symptoms and causes … First, don’t do testing like that in your own home. Learn by watching the video, not by being a copycat. Residential plumbing codes in most jurisdictions in the USA have an upper limit of 80 PSI as the maximum pressure to feed plumbing fixtures. In many places the incoming municipal water will have a pressure well above that (my house had 105 PSI when I last measured it), so a pressure reducing valve (PRV) is installed just past the water meter. As far as I know, all PRVs for residential water prevent back flow to the water meter; and many water meters also prevent back flow into the water service lines. So expanded water isn’t able to flow back into the water service lines in most cases. So where does it go if there is no expansion tank and the T&P isn’t dripping? Old ball float toilet valves were good for letting the expanded water flow through them and then down the overflow tube ;) Old faucets with washers and seats would often have a wear point that would let the expanded water drip through. So it’s quite possible that a dripping faucet or running toilet is an indicator that you need an expansion tank.

I'm renting a house the plumber they sent out didn't even know how to test the system I found out that he's a apprentice plumber and works in rough install. Thank you very much for the effort. You are keeping me at JACK of all trades

Excellent demonstration. Well done!

This is all very simple, but what is usually missed is that you do NOT need one of these unless you have a backflow preventer. most old houses do NOT have such a thing, so when the water begins to expand it simply pushes the extra volume back into the water main. Water supply systems use centrifugal pumps, and thus water can be pushed backwards through them, and on a huge city system, there is always a tap open somewhere.

Wasn't sure if I was going to watch the whole video but I am so glad I did. Best demonstration video in the history of ever! Thank you so much for the break down of everything. Amazing Job!!

I learned a lot from this video. Thanks a lot for putting in the effort to educate everyone on this important topic not many people pay attention to

One of the best demonstrations I’ve ever seen. Very well done!

Great video. I never had thermal expansion tanks on homes I owned or lived in near Chicago. I have one in my home near Dallas and had to replace it this past weekend when the old one sprung a leak. I enjoyed getting an understanding of its purpose.

Many thanks. I'm a landlord of 20 properties and never thought it was important to spend the extra for an expansion tank. Guess I have work todo installing some expansion tanks! Very good video. Explained well.

Hopefully done a good job he says This is a definitive video for the explanation of the use and need for a hot water expansion tank. Thank you

Awesome demonstration. Thanks for putting in the work on this.

Absolutely awesome video. Many engineering courses teach this science, but you gave us a great visualization of this application in the practical world and you also demonstrated the things that can go wrong if you don’t address it properly with components like expansion tanks. You also showed what negative pressure can do to a thin walled cylinder (like a water heater tank) when negative line pressure / vacuum collapsed the plastic bottle. I know in some older cities in Massachusetts, you need a vacuum break on your hot water heater tank. As I’m told, if a fire truck starts sucking water from a nearby hydrant and you do not have a water line check valve in your home, then it could result in the collapse of your hot water heater tank, so awesome demonstration. Thank you for pulling this together.

Fascinating; thanks for sharing. I didn’t know about the function of the relief tank - I thought it was to prevent water hammer. Originally I didn’t have the pressure tank in my system. Last time I replaced the water heater, the plumber took it upon himself to add the pressure tank. Now I see he was a competent technician who kept up with best industry practice.

For the first time, I had pleasure clicking the thumbs up 👍🏽 button.

That is the most understandable explanation I have ever seen to express the need for expansion tanks on water heaters. I appreciate all the visuals you used to demonstrate what is really happening inside that water heater. Awesome job.

Great explanation of the expansion tank and why it is needed. When I bought my 60 year old house a few years ago I installed a whole house filter system. Along with the filters I put in a PRV, which my house did not have originally. I found that the water pressure coming into my house was around 120 - 125 psi. I set the PRV to 60 psi and thought everything was good. A few days later my filters were leaking and the pressure had increased back to 120 psi after the filters. I thought the PRV had gone bad and the mfg sent me a replacement, the same thing happened. Then I did some digging around and figured out my problem was there was never an expansion tank installed in my home. I put one in and have since never had any issues. I recently replaced my 20 year old water heater in this house and found that the T&P valve was non functional. You would think that a home inspector would test these things when you pay them to check the home for issues before buying it.

Historically, this wasn't an issue in municipalities. What has happened since is that the water companies have installed new meters that are 'tighter' internally. The excess pressure from residential WH's formally used to travel towards the city's meters and beyond. This caused them all kinds of issues on their pumping side. Now, the excess pressures can no longer pass into the city systems. However, residential customers didn't understand why their T&P valves were suddenly seeping/leaking one day. And in the beginning, when this started to be a problem, municipalities were silent to the plumbers and the public about what was happening. I remember this well. Now it's common knowledge, but it wasn't always so. The municipalities didn't want to be blamed for leaking, in house HW services when all they were doing was protecting their pumping stages/equipment.

What an amazing job explaining things such a clear manor. Great teacher! Thank you

This is the most lifesome lesson that I have ever learned in the industry! Bravo !

I've taught apprentices in the past and your presentation is excellent! I have one tip and one question: TIP - I've used something called a "bottle bushing", it's a plastic adapter bushing that you glue into a PVC socket and it uses an O-ring to seal the joint between the bushing and bottle, I've not used mine under system pressure but for my use it's been leak free. A simple google search will take you to the website where I got mine from. QUESTION - Can you mount the expansion tank above the system piping (essentially up-side down) to help with system drain down i.e. when closing and winterizing a cottage for the winter?

Wow! A rare and great lecture by a plumber who knows the "how" of the trade and also understand the "why" of the theory behind it. Would love to see you shine some light on how to properly charge a thermal expansion tank. Is the factory charge of 40? psi good for all residential houses?

Hi from north of ya -Iowa- the way you speak so humbly makes me feel more thankful that I am in the right trade . Wish I had more time to work out a plan to work for myself and make people happy . Raising 4 kids takes lotta time away for things you wanna do and venture ! Keep it up boss !

Great information. That demonstration helped me understand the importance of a thermal expansion tank. Thank You!

This is really a "compression" tank, not an "expansion" tank. There's a difference. The compression tank compresses the trapped air in the tank, separated from the water by the diaphragm, while an expansion tank is open to the atmosphere. FYI 🤔

Shame shame, First of all you did not tell all your viewers weather or not you were on city water or well water or if you had a pressure reducing valve on your city water and you know what a difference that would make The only time you would need a expansion tank on a hot water system other than a heating Boiler is if you had a closed heat system. When you are connected to the city water there will never be a pressure rise from a water heater heating up because it will expand to the city water system and if you were connected to a well system you would have a well expansion tank on that also, which will also work for the heat expansion of the water heater heating up. In most cases dam near all you will not need a expansion tank on your water heater. Waste of you money.

Outstanding explanation, thank you. Being from the old school when we were informed for the need an expansion tank it was perplexing. What are and for, what reason do we now needed one when for decades there were not such a thing. They told us "it is now code" without any further explanation. Again, thank you for your video. In your next video mount the camera. It is unnerving watching a video with the camera bouncing around, where do we focus? Oh, please remove the background music, it is very distracting and annoying. It is beyond me why RU-vid content creators think it cool-cute-necessary, having music playing over their voice. We came to hear you, not fight the music. Many folks have hearing difficulties, thus when we attempt to hear the spoken works and there is music as well, we cannot turn up the volume without turning up the volume of the music. In a word frustrating. To understand what you are saying what we must do is turn on the CC. Hope this makes sense.

The best demonstration about the purpose of an expansion tank, and how it functions. Job well done, well done!!!!!!!

This is an awesome explainer video! Thank you! Now I am educated and can educate 😊

Outstanding video that teaches the plumbing. Good job i learned a lot from you.

OKAY, IMO,,,,,,,,,,THEE BEST PLUMBING VIDEO I EVER SAW DEALING WITH ANY SUBJECT........I DEBATED WATCHING CAUSE I CAN'T WATCH LONG TEACHING VIDEOS...............TOO MUCH NONSENSE AND USELESS JIBBER JABBER..........THIS ONE HAD NONE OF THESE DRAWBACKS..........YOU ARE AN EXCELLENT TEACHER.......YOU EXPLAIN TO BE UNDERSTOOD...........I LEARNED A LOT...........SUBSCRIBED ,,,,,,,,,,,AND LOOK FORWARD TO MORE OF YOUR VIDEOS.........CAN'T BELIEVE 31 MINUTES WENT THAT FAST AND I DIDN'T FAST FORWARD ONE SECOND OF THE VIDEO.........A GREAT BEYOND GREAT VIDEO........WISH MORE WERE LIKE YOURS...........YOU DON'T TALK TOO FAST OR SLOW,,,,,,,,,,,JUST RIGHT,,,,,,,,,,,,,ONCE AGAIN JUST MY OPINION.........BUT PROBABLY A LOT OF OTHERS TOO...

Good show. I have an old house with many old copper connections throughout. I just replaced my 1985, A.O. Smith gas 50 gal with the same make and size. What a difference this new one makes. Even though I have an open system ( no backflow or check valve at the meter) your video has convinced me to install an expansion tank AND a supply regulator. The last thing I need is an old solder joint breaking loose in a 100 year old house. Thanks again

Thanks for the training. There was no such training back 10 years ago. I have been lacking such info. Your training gives me good tips in Plumbing. Thanks.

You give good examples of the concepts. I think you did and are doing a great job.

The best Explanation I had see so far, Thank you so much for this great video and May God Bless you .

Thank You for nerding out on this! People don’t understand this stuff but definitely need to understand that

Great demonstration!

Thanks for showing this, and God bless you!

Excellent demonstration - Thanks

Very nice demonstration, thank you for that.

Excellent presentation!

Thanks for the video, very illustrative and it is clear lot of effort went into producing it!

Thank you man. This was so educational. It helped me better understand the workings of an expansion tank and a water heater. I just started my apprenticeship program so I was really glad I found this video.

Awesome demonstration and description, thanks for sharing.

Excellent video! Thank you, sir.

great video explains it all with regards to expansion tanks and boiler/ hot water tank safety

Holy smokes that was one of the best demonstrations I've ever seen... thanks you so much for that brilliantly detailed example!

What a great video for understanding how an expansion tank works and why I need to install one on my water heater.

This is by far the best review I've seen thanks so much for sharing

Best video I have seen explaining the expansion tank operation and purpose.

This is a very clear and excellently explained video. Thank you.

Very thorough explanation and visual presentation was awesome!

Absolutely fantastic video. Extremely helpful

Very clear well said explanation of the pressure in hot water tanks

Really explained the purpose of a thermal expansion tank. Fine job.

One of the most amazing and important experiments . Very very helpful . I deal with water systems and this video gives me a good reason to explain my cuustomers to go for the expansion tanks .