Do I need a thermal expansion tank? - Let's do an experiment!
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Published 2023-01-07
Well, the simple answer is because it saves your water heater from becoming a rocket. BOOM!
The long answer is because as water increases in temperature, it also increases in volume. So when we have a sealed system, That added volume of water will turn into tremendous pressure. That is unless we provide a place for that added volume of water to go.
First, we display just how much added water volume is created when we heat a 50 gallon tank of water. You'll be surprised at how fast it happens too!
Next, we perform the same test again but this time the pipes are sealed up so the added volume of water has nowhere to go. This means it turns into water pressure. It only takes a few minutes for the pressure to exceed 150 psi.
From there, we display a clear thermal expansion tank so you can see exactly what happens inside a thermal expansion tank. As the volume of water increases, the size of the rubber bladder decreases. This allows the water pressure to remain stable.
Finally, we showcase what happens to the water pressure when we install a thermal expansion tank. It's pretty neat to watch the pressure gauge while the thermal expansion tank get to work.
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@WattsWater @StateWaterHeaters @AOSmithWaterProducts @bradfordwhitewaterheaters5020 @rheemwaterheatertraining @fergusonenterprises @HomeDepot @lowes @menards
All Comments (21)
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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
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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... -
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. 😁
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This is one of the best documentary on expansion tank.
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I'm over here wondering why our public schools don't do what you just did. You sir are a legend. Keep it up!!
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HVAC guy here. This video was awesome. Thank you!
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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! -
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!! ❤😊❤
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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!
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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...
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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.
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Yes my friend , you did wonderful job for mechsnical contractor
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I bought this water heater youtube.com/post/Ugkx8G49mV71sAzUl9shXyLW-r3XgHH9E… 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.
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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.👍🏻
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Owned many homes for decades, never needed an expansion tank. Never had a problem
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No one could have done a more thorough and effective job of explaining all this as you did. I learned so much. Great job!
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Thanks for taking your time to show us this. Excellent work!
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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
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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!
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Greetings from the Gambia🇬🇲. Im a plumber in my 5th year apprenticeship. You can follow nice meeting my fellow plumbers😊❤
