What Is This Tank? How to Replace and Maintain a Water Heater Thermal Expansion Tank

hey everybody today I want to talk about water heater expansion tanks this is my expansion tank for my heater and in case you're not familiar with what an expansion tank is or why you might need it I'm going to link to a video I found that really does a great job it's only about a minute and a half long explaining why these are important and how they work I'll put that down in the description super briefly though inside your tank is obviously a bunch of water and as it heats up it's got to expand because you know physics and that water once it expands has to go somewhere because water is not compressible now if you don't have an expansion tank then it could try and go back out to the cold side or your municipal supply or wherever your water comes from in the first place but many of those have a check valve installed which means that it's a one-way kind of a flow it can't flow back out as it expands and as a result you wind up just putting extra pressure on the liner of your tank and potentially damaging some of the appliances in your home that are connected directly to the hot water so to deal with this pressure you probably have an expansion tank like this installed somewhere near your water heater the way these things work is half the tank is going to be full of compressed air and the other half contains a bladder that is going to be hooked up to the cold side of your water heater and as your heater heats up the water and it expands it will be allowed to fill that bladder and push against that compressed air and that compressed air provides on equilibrium so that the water flows into the tank but doesn't completely fill it so it's really important that the air pressure at the top of this be maintained in the correct range otherwise these tanks can fail well what happens when they fail well the bladder inside there can rupture which will let water flow in and fill up the entire tank and then it's not doing you any good and you're just putting all that extra pressure and stress on your heating system like you were without a tank in the first place so how can you tell when one of these things has failed well for most people the first telltale sign that you've got a problem with your expansion tank is actually leaks coming out of your temperature and pressure valve or your T&P now I did a whole video all about T&P valve so I'll link to it right up here but even if you've replaced a TMP and it's brand new and working properly it will leak if your expansion tank is met functioning alright IV ambered on enough about what these things are for and why you need one let me show you how to test it properly and how to replace one when it's failed as I mentioned before the air pressure in this tank needs to match the pressure of your water supply and so the first thing I'm going to do is measure the pressure of my water supply using this pressure gage be sure when you measure the pressure that you do it on a hose bib or some other fixture that does not have any pressure reducing valves installed and it might be a little hard to read here but my pressure is reading at about 75 psi so that's what I'm gonna aim for in my expansion tank now I mentioned before that one of the tell-tale signs that you have a failed expansion tank is that your T&P valve is going to leak and typically this will happen during the heat cycle of your heater so it won't be a steady slow drip all the time it will just happen when somebody has just finished taking a shower or when you run a load of laundry and you're just reheating all the water in the tank this bucket here is filled with about two weeks or so worth of slow leaks that are happening only when somebody actually uses the hot water in my home so in order to accurately measure the pressure in this tank the first thing we need to do is depressurize the water side of the system so we're gonna turn off our cold water inlet that is typically located above your water heater and then we'll open the hot side of the faucet and let it flow until the water stops once all of the water pressure has been relieved from the system now we can accurately measure what the air pressure is inside of our expansion tank and as you can see here I've barely got even 10 psi in this tank so it is way too low and that's likely why things are leaking when the heater is heating the water so if when you measure your tank you find that it's just really low like this one the easiest remedy of course is just to repressurize it to the correct pressure you'll want to use an air compressor to fill these if you've got one but a bike pump can work too though it'll take a long time so I'll replace the plastic cap that goes on top to protect that little valve and we'll leave it for a few days or a week and come back and recheck the pressure now if the pressure has not changed and there's no more leaks than you've solved the problem but if the pressure is down again or if your tank continues to leak then you need to probably go ahead and replace this expansion tank now if when you go to check the pressure you have water come out of valve instead of just air then the tank definitely has failed and you must replace it alright so getting into the replacement process after you have depressurized the system turn off your heat source in my case I'm just gonna set it to the pilot settings so that I don't have to turn off the pilot light but it will not turn on the burner and then since there's water up in this tank we're going to open up the drain valve at the bottom of the heater down here and drain off a couple of gallons or so of the water just so that when we do remove this tank we don't have any water come pouring out the bottom of it and make a big mess everywhere you definitely don't need to drain the entire tank here all you're trying to do is make sure that the expansion tank does not have any water left in it once you've drained off enough water then you want to secure the plumbing that the expansion tank is attached to with one wrench and then just unscrew the expansion tank once it's nice and loose you can just spin it right off and lift it off and out of the way now this is the expansion tank I'm going to be using as the replacement as you can see it comes charged from the factory at 40 psi and this is a little larger tank than I originally had and there's nothing wrong with putting in a larger one but don't put in something that's smaller here you can see I'm just verifying that it is 40 psi from the factory so before I even install it I'm gonna go ahead and make sure that it's pressurized to the correct pressure for my system which is again about 75 psi but will vary depending on where you get your water so make sure your pressure matches your system you may have noticed I'm using one valve to check both water and air and I'll leave a link to a video where I describe exactly how I set that up then you're gonna want to seal your threads I like to use both teflon tape and pipe dope to make sure that nothing is gonna leak then you can just screw in the new tank and tighten it down again supporting the extra plumbing with a secondary wrench then replace the plastic cover over the Schrader valve on top of your tank and don't forget to turn on your cold water supply to the water heater again when you do that water should start flowing back out of the faucet and you may also get a little bit of air at the beginning leave that faucet flowing until all the air has been purged out of the system and the water is flowing like normal and of course don't forget to reenable the heat source for your heater just set it back to where you like it and lastly I want to mention the importance of supporting the expansion tanks weight waterway is a little over 8 pounds a gallon and while these tanks are not very heavy when they're empty once they start filling up with water that they do get quite heavy I'm using a bracket that I purchased off the shelf at my local hardware store and in order to mount it I'm using a piece of wood that I'm going to use kind of as a backing plate to stretch from one stud to the next in my wall and I'm putting the backing plate in first so I can hold up the bracket to get an accurate location of where that bracket is going to need to be installed otherwise it's really difficult to locate exactly where the bracket needs to be in relation to where the tank is if you try and do this before you have the tank actually on the wall with the bracket marked I can then take the backing plate off the wall and permanently affixed the bracket to the backing plate with some little nuts and bolts now this particular bracket didn't come with any instructions so I just decided to use those three holes in the center but as you can see here when I tried to put the strap through it interfered with the mounting location there so I just moved one of those to a different hole and problem solved this bracket is the kind that comes with some steel straps that wrap around your tank and it'll fit tanks of various sizes and it's kind of a universal fit situation so if your tank is near a wall this is a great way to mount it if your tanks in a different orientation or is not near a wall you might have to get a little more creative though with how you mount it one more quick tip for you I didn't want to have the extra length of these steel straps kind of dangling where something could potentially get caught on them so I just used a couple of zip ties to tie them down a little tighter and one of my pet peeves about zip ties is people who install them and then just cut off the ends because it leaves a really sharp little corner there so I always like to twist off my extra end it doesn't leave anything sharp and still looks nice and neat and finally with a quick check for leaks to make sure that nothing's well leaking then we're all finished I hope you can see just how easy it is to maintain an expansion tank like this and it's also really important that you do so because a failure in this can lead to bigger failures elsewhere in your plumbing system that are both much more difficult and much more expensive to take care of I hope you've enjoyed this video and maybe even learned a little something from it if you have and you'd like to let me know you could hit me with little thumbs up down below there and if you found that there's something I could have done better you've got a suggestion for how I could improve I'd love to hear about that down in the comments as well and if you'd like to see more content like this of course you can think about subscribing but there's no pressure there of course and as always thank you very much for watching that membrane or that rubber bladder so the bladder just sits there and does bladder things I gotta pee listen

Channel: AmplifyDIY

Views: 706,168

Keywords: thermal expansion tank, water heater expansion tank, hot water expansion tank, water heater expansion tank installation, water heater expansion tank maintenance, expansion tank, install expansion tank, expansion tank replacement, why expansion tank, expansion tank installation, pressure expansion tank, thing above water heater, expansion tank pressure, hot water expansion, water heater expansion tank test, expansion tank how it works, water heater, Hot water heater

Id: NGygvtP6Sdk

Length: 10min 24sec (624 seconds)

Published: Sat May 16 2020