Basic Guide for Tanked Water Heater Replacement
- Jesse Kirk
- Apr 1
- 13 min read
Thank you for choosing the ultimate guide for water heater replacement, this post will answer all your questions about replacing a standard water heater. Hydro Plumbing is a top rated plumbing company, we do water heater replacements at a high level and are happy to share this expert level information to you on our blog. We know how hard it is to find useful information, specifically on water heater replacement. There are also many things that you should and should not do during this process and we will point out all of the important information you need to know along the way. If you are not going to complete the replacement yourself, you can use this guide to walk someone else through the process or make sure you hire a plumber that is worth paying.
Below in this guide you will find everything you need to know about water heater replacement. Please enjoy the content below and reach out to us or comment if you have any questions.
Water Heater Replacement: Save Thousands of Dollars and Learn a New Skill!
Are you ready to be a water heater replacement hero? Do you want to impress somebody and pretend like you are a plumber for a day? This guide will help you with the water heater replacement information you need. Read this entire guide to make sure you do not miss something on your water heater replacement.
Water Heater Inputs and Shut-Offs
Start by finding the water lines going from the water heater to the plumbing system. Feel the pipes, one should be hot and one should be cold, if both are hot run your hot water and the cold water pipe will cool down. Identify which pipe is hot and which is cold, there should be a shut-off valve on the cold water side. This is the input to the water heater, cold water from your main water supply. The other side is the hot water output. The cold water pressure is used to push the hot water out the output of the water heater. The reason there is a shutoff valve on the cold water input is for serviceability. We want to service the water heater without shutting down water to the rest of the plumbing system. Without a shut-off valve on the cold inlet we would need to shut down the system at another location such as the meter box, well pump house or another shut-off valve on the plumbing system. Either way the water needs to be shut off to the water heater and a good way to check to see if that has happened is to turn on the hot water and see if anything comes out. At first there may be some pressure or water still in the lines, but shortly after the hot water should slow down to nothing. If you still have pressured water on the hot water side after turning the water off at the shut-off valve supplying the water heater or the main plumbing system, then there is still cold water being supplied to the water heater. That means the shut-off valve is not shutting off the water supply, and has failed or you have shut off the wrong valve! Did you just shut your neighbors water supply down? Highly possible, those meter boxes can be tricky. Is the shut-off valve on the hot water side rather than the cold water side of the water heater? Then you would not be shutting off the cold water inlet like we need to be, you are shutting off the hot water outlet. If there is a shut-off valve on the wrong side, or hot output side of the water heater that is completely useless for replacing a water heater and you will need to go to the street or another shut-off in order to get the cold inlet off. In some rare cases you will go check your hot water at a sink and it will still be pressurized! This means that the valve at the meter box is faulty. If you have a well, then you can find a shutoff as well like described above, or shut power down to the pump at the electrical panel. Always make sure the water is off before proceeding.
Next look to see if you have an electrical wire going to the water heater. If you do then you have electricity running to your electric water heater and will need to turn it off before disconnecting it at the service panel. There will be a breaker to shut off the power to the water heater, turn it off. You can check this with an electrical meter, always make sure the power is off before proceeding.
Finally, if you do not see an electrical wire to the water heater then there is a gas line supplying natural gas to your gas water heater. That gas line will have a shut-off valve and flex line going to the water heater. Locate the shut off valve and turn it off. If there is no shut off valve you can shut the gas down stream somewhere else, or at the gas meter. To make sure the gas is off, try to restart the pilot light. There should be no gas to the water heater and no way to restart the water heater pilot light. Always make sure the gas is off before proceeding.
Water Heater Removal and Disposal
We got everything shutoff and have verified that all systems are off, now it is time to remove the existing water heater. Firs tog check the meter and see if there are leaks. It will be hard to diagnose if there is a new leak, if there is currently a leak already! If you have a leak deal with that first, then go back to your water heater. Disconnect the water lines, electrical line, and or gas line from the water heater. If you have a gas water heater, then remove the draft diverter and ducting from the water heater. There might be some screws or tape holding these items together, remove as needed. The draft diverter has little tabs that slide into the top of the water heater, almost like little clips. They come right out. See diagram 2 below to locate the draft diverter and exhaust ducting flue. If there is an expansion tank on or near the water heater, remove it as well.
Next check for earthquake straps, two bands that hold the water heater in place. They should be screwed into the wall studs and fit tightly around the water heater. In the event that the water heater could be moved, such as during an earthquake the straps will keep it secure to the mounting area. If the water heater moves to much then the piping could break and cause a leak. Remove them if you would like to replace them, or you can leave them connected to the wall and disconnect in the middle. Leaving the straps hanging on the wall to be reused is good as long as they look good, feel strongly secured to the wall, and will fit the replacement water heater. Either way it is a good idea to see how things go together and come apart so later on you can quickly install your earth quake straps. Take a photo of them before you demo.
All utilities have been shut off and disconnected from the water heater, the earthquake straps have been removed completely or left connected to the wall but opened up in the middle of the straps. The expansion tank has been removed. All that is left is the water heater pan under the water heater and the temperature-pressure relief valve and piping. You can leave the water heater pan in place for now, and unscrew the temperature-pressure relief piping from the valve. This can be reused on the replacement, or thrown away and replaced.
Before we remove the water heater, drain the water from it. Hook up a hose to the drain valve, open up the drain valve and watch it go. You can use a pump and pump the water from the water heater to speed up the process. After the tank has drained, disconnect the hose. It is now time to remove the water heater.
Grab the water heater firmly, move it out of the pan and out of the installation area onto a dolly. Load it up and take it to the dump, sell it on eBay, or add it to your collection of used water heaters. Time to make room for the replacement water heater.
Water Heater Expansion Tanks
Rather your water heater has an expansion tank or not you will need to verify if there is pressure reducing valve or not. If you have an open or closed plumbing system is how you will determine if you need an expansion tank for the replacement. A closed plumbing system will have a pressure reducing valve which does not allow water to flow backwards back towards the input. An open plumbing system means that there is no pressure reducing valve or any device in place to keep the water from going back towards the input. In an open system if the water expands it can go backwards if the inlet valve is open. In a closed system the pressure reducing valve would stop the water from expanding past it, which is why an expansion tank is installed between the cold water inlet to the plumbing system, and the cold water inlet to the water heater. It serves as a point for the expansion to occur, keeping temperature and pressure stable. Ever wonder why your pressure reducing valve is discharging hot water in the pan? With a pressure reducing valve and no expansion tank the hot water pressure builds up when the system is not in use and the temperature-pressure relief valve discharges the excess pressure. Adding a tank would solve that problem. It is best practice to just install one, as it takes less time to install the expansion tank than it does to locate the pressure reducing valve in some cases and the cost of adding the tank is less than $100 in parts depending on what size tank is used. A two gallon tank is standard for a 50 gal at 140 degrees at 60psi. There are expansion tank calculators if you want to be a nerd about it.
Water Heater Installation
Make sure you have all the materials and tools needed for the water heater replacement process to go smooth. Tools:
crescent wrenches
pipe wrenches
drill
screw drivers
plyers
dolly
hose
Materials:
thread sealant tape
pipe joint lubricant
water heater pan
earthquake straps
expansion tank
3/4" shutoff valve with male on one end and female on other end
3/4" flexible water heater lines
3/4" hex nipple male pipe adaptor
swivel expansion tank tee
discharge or run-off tube
ac/mc/flex combination connector 3/8"
3 white wire nuts
high heat HVAC metal tape
Once you have all the tools and materials you need along with the water heater you are ready to begin the installation of the water heater.
Step 1: Install the water heater pan. Lay it on the ground or stand where the water heater will go pointing the drain port down hill or towards where you would like the water to go. We prefer plastic water heater pans as metal ones tend to bend or deform if you have a tight installation and happen to contact the water heater to the side of the pan.
Step 2: Install the earthquake straps. If you are using the old ones or have new ones installed already, make sure you can access the straps after the water heater has been placed. This will keep you from having to pull the water heater to grab them, so keep this in mind when placing the water heater and thee straps. Make sure to measure where the straps will go on the water heater to make sure it does not contact a part on the water heater other than the tank itself.
Step 3: Install the new shutoff valve. Even though it is off, if you remove the existing valve without turning the main water supply off you will have a bad day. Please make sure that the water is off before proceeding. After removing the old valve, clean the threads with a light wire brush, removing debris. Add pipe thread sealant tape around the pipe threads clockwise, stretch it on a bit and get it on there good. The fittings are tightened clockwise so the tape stays on when tightening. Next apply pipe joint lubricant over the tape. This makes installation easier and adds another layer of leak protection.
Step 4: Install the new 3/4" flexible water heater lines onto the plumbing system pipes, leave them disconnected from the water heater for now. Do not over tighten the lines, only tighten enough to seat the rubber seals. You can over tighten and crush or misalign the seals if you keep going and going! You can always tighten them up if they are to loose but you can not go back and loosen if they start leaking from over tightening typically this will require a new seal.
Step 5: Install the water heater components, such as: temperature-pressure relief valve, discharge or run off piping, expansion tank tee and fittings, expansion tank. One at a time, each fitting gets sealant tape and joint lubricant then is tightened snug. With no rubber seals these products help seal this connection. You can most likely not over tighten these pipe fittings unless you are seriously strong but try to snug them up as best you can without sweating. The water heater is now assembled and ready to be situated.
Step 6: Prepare the components and materials used for the placement of the water heater, get everything aligned and try to think about how to not do this again. Pull out and ger the earthquake straps out of the way, move flexible lines up, position the expansion take to fit. Make sure the flexible lines look like they will be able to do there job, sometimes shorter or longer lines work better. Also adding more fittings, such as 90s and nipples can allow the flexible lines to be installed more easily or with less bending. If the water heater is electric, make sure the wire is out of the way and accessible after placement. If the water heater is gas make sure the gas line is out of the way and accessible after the water heater is placed, also make sure the exhaust ducting flue is lifted enough or removed in order to fit the replacement water heater. We are now ready for placement.
Step 7: Place the water heater into the final location. This is easier with two people sometimes. Be careful not to hurt the water heater, components or yourself when doing this part! It is pretty a straight forward step, once it is place try to cent it and align things as best you can.
Step 8: Make all the remaining connections other than the electric or gas. Start with the earthquake straps, go back to when you did demo and hook them up the same way they were before. If you have new ones, try to mimic how you saw they were attached with original connections. Get them lightly snug, we want the straps firmly holding the tank without moving it off center, or crushing the tank in the process. Next would be the other sides of the flexible lines, try to bend them one time to the shape you would like. Then hand tighten, when you go to tighten them with a crescent hold the lines and try to keep them from spinning or moving. When they start to spin or move it is probably tight enough. Make sure the expansion tank it where you want it and the connections are tight. Assemble the temperature-pressure relief valve if it is not already installed, then screw the discharge or run off tube into the temperature-pressure relief valve making sure that you applied tape and joint lubricant to it like everything else that doesn't have a rubber seal. There is typically a hole and fitting in the pan of the water heater assembly, screw that on so the pipe part is sticking out of the pan and the nut is tightened on the inside. If the pan fills with water then the water will go out that pipe. If that is okay, then leave it how it is. If you would like to hook up piping to that connection and run the pipe else where you can do that at this time. We saved the electric and gas until the end so this step doesn't get skipped. Go turn on your water slowly and watch your connections as this happens, or get help with someone by the shut-off and other by the install. Check for leaks. Go turn on all the hot water fixtures in the building. You can leave them running for a few minutes until the air bleeds out. When the sound of air gushing out of the system stops, you have bled the system. We want to remove all the air out of the hot and cold lines at this time, the majority of the air will be in the hot line. After you are sure all the air it out you can turn off all the fixtures and check for leaks again. Feel, look, touch for leaks. Then go to your meter if you have one on the street and see if you have a leak. If the little meter triangle is spinning, numbers are going up, or there is a little plus somewhere on the screen, you have a leak. As we know there was no other leaks before, this must be from the water heater installation. Go back and fix the issue before proceeding. Might need more tape and lubricant, need to be tightened more, or there is an issue with the rubber seal. After all connections are good and there are no leaks, hook up the gas or electrical connection. Along with the exhaust ducting flue. Hook up the connections like they were, if you see tape and dope on the pipes then you will need to re-apply and if there is nothing then you will just need to tighten up the fittings. Get them tight. You can put high heat HVAC metal tape around the joints of the exhaust ducting flue and the connection of the flue to the draft diverter. For electrical connections, install the ac/mc/flex combination connector 3/8" at this time. The nut will tighten from the bottom of the plate and be inside the electrical box when installed, the clamp is accessible from the top. Put the wire providing power to the water heater through the top of the connector and then connect the wires. Make sure the wire nuts you are using to connect each wire is screwing on the wires securely. If you can pull the wires out of the wire nut after it has been tightened on, try again until the wires are all tight in the wire nut. Use your new wire nuts, not the old ones! Connect the ground and make sure to put the top back on the electrical box. Tighten up the screws in the ac/mc/flex combination connector 3/8" clamp. Should be good to go.
Step 9: Double check everything, open up the hot and colds making sure there is no air. Turn on the electrical breaker, or the gas valve.
Step 10: Start it up. If you have an electric water heater you can go to the next step, your water heater is on and heating up. For gas, push down the pilot button and let the gas get moving. Get the air out of the gas line system, this will not take long and you will smell gas soon. Follow the manufacture instructions on your water heater for starting. Typically involves lighting a holding down the pilot button, hitting the igniter until you see a flame, hold down the pilot button after the flame is lit for a short time, then slowly release the button. Set the temperature knob. Make sure there are no drafts or air moving around the area when yo do this. Once the flame is lit and burning, turn the knob the the desired setting. Start at med, or about 120f and go from there.
Step 11: Clean up area and wipe down that beautiful new water heater you just installed. Comment, ask questions, leave us a 5 star review! We are happy to help :)
HYDRO PLUMBING: WATER HEATER REPLACEMENT
From getting the right water heater to bleeding the system we have gone over the basics of a water heater installation. There are more options or materials that can be added to this process, lots of other ways to do this as well. We hope that you can take this information and use it to assist in your water heater replacement. Here are some of the brands we use:
We offer water heater services along with anything else you may run into with your plumbing system at www.hydroplumbing.org. Contact us anytime.
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