How to Replace RV Water Heater Thermostat (Test and Adjust)

Hot water does so much for everyone. It helps clean the dishes, makes them germ-free, and so on. Plus, it helps keep everyone nice and clean as well as germ-free. But hot water also relaxes tired muscles and makes you feel better. That is until the thermostat breaks.

We are talking about the thermostat on the water heater unit itself. First, you need to pull the wires off, then remove the old part. Then put the new thermostat in place and attach the wires. Leave the ECO in place and do not disconnect it.

Where is The Thermostat On An Atwood Water Heater?


If it is like the water heater we looked at, the thermostat will be on the water heater itself and you get to it through the exterior access door. The thermostat will be front and center next to the ECO control.

Just open the access door and you should see it right in front of you. If you don’t, do not worry, the thermostat and the ECO are clearly marked. You cannot mistake one for the other. The label may only say T stat but that is the thermostat.

The reason many RV and trailer owners replace the original unit is because the RV makers have been installing non-adjustable devices. They are set to open when the water temperature reaches 140 degrees F.

For many people, that level is just too hot to handle and not very comfortable. So they replace that original thermostat with an adjustable model. That way they can control the water temperature a lot better and have a nice shower.

Atwood is said to make an adjustable thermostat, although we are not sure of the price of that unit is at this time. There may be other brands that do this as well and maybe more reasonable in costs.

How to Tell if RV Water Heater Thermostat is Bad

There are different tests you can do but the best test is to turn on your faucet. If the water runs cold from the moment you turn on the hot water faucet, then you have a bad upper thermostat.

However, if you turn the hot water faucet on and it runs hot for a little bit then turns cold, you have a bad lower thermostat. But those may not be the actual source for the cold water. It could be that your fuse or breaker blew and shut off any electricity to that unit.

You should check the fuses and the breaker box to make sure they are in top working order. Or you can use a multimeter to see if any power is getting to the thermostat. If there is none, then check other sources for this problem. If there is power going to the thermostat, and you are still not getting hot water, then you need to change this part.

It is not a difficult job to get done. There are a few steps involved but it should not take you longer than 30 minutes to make the change. Just be careful as you go as some parts holding the thermostat may be plastic.

How to Test an RV Water Heater Thermostat


The first step in this process will be to go get your multimeter. Place the probes on terminals 1 & 3 and look for a 240 volt reading on the dial. if you do not get that reading, go and check the power source to make sure it is delivering power.

Also, check the current on the high limit switch. The next step would be to disengage the lower thermostat and turn the temperature up on the higher one if you can. Then look to see if there are any faults.

Step three would have you placing the probes on terminal one and the blue wire on the heating element. What this does is tell you if any power is being transferred between the upper element and the blue wire.

If you get a 240-volt reading when placing the prongs on the 1 and 3 terminals, then you move the probes to terminal 2 and the blue wire of the heating element. If there is no power or reading on the dial, then the thermostat has gone bad on you.

Do the same for the lower thermostat except that you are turning the temperature down as far as it will go if you can make the adjustment. Then you use the red wire instead of the blue wire.

Place the probe on terminal 1 and the other on the red wire, if there is a 240 reading that means you have power. Next, go to terminal 2 and the red wire and if you do not get a reading, then you have no power and you need to replace the thermostat.

How do I Change the Thermostat In My RV Hot Water Heater?

This is relatively easy and should not take that much time to do. The first step is to remove the wires and then the padded label from around the thermostat if there is one. Next, you will need to loosen some clips which will allow you to remove the plastic ring behind the part.

Once the ring is removed, the thermostat should come out very easily. Sometimes the replacement part is a little larger than the original. When you are in that situation, you can remove the tabs to make the new one fit in place.

When you put the new thermostat in place, make sure it touches the tank. The spring will help do that but you need to double-check because if the thermostat is not touching the tank, the water will overheat.

Once the new thermostat is in place, you are done. If you used an adjustable replacement, this is the time to set the temperature level to your preferred heat setting. A screwdriver will do that. Just turn the screwdriver to the left if you want a cooler temperature.

If you want a hotter water level then turn the screw to the right. The setting will be done by trial and error and after a while, you will find the right setting for you and your family.

Replacing RV Water Heater Thermostat


You really do not need a lot of handyman skills to do this repair. If you can handle a utility knife and a screwdriver, this project should only take a few minutes to do. The hardest part will be removing the rings and clips.

Putting the spring back in place when you are adding the new thermostat is the next hardest part to do. The key to this repair is the size of the thermostat. Some replacement parts are larger than the original so you may have to do some adapting to get it to fit.

That adapting usually means bending or removing the tabs that held the original part in place. There should be some instructions that come with the replacement thermostat but if there isn’t, there are plenty of videos on YouTube showing you how it should be done.

We should mention that any instructions here may not work for different models of water heaters. Each RV maker may have their own design and will not use the methods we have described.

How to Adjust RV Water Heater Thermostat

In recent years, RV makers have gone to limiting the thermostat. They have put in a non-adjustable part that you cannot control no matter what you do. It is set at 140 degrees F and that is the heat level you are stuck with.

The way to adjust your water heat level is to remove this non-adjustable thermostat and replace it with an adjustable one. That is not that hard to do as you have already read.

Once you have the adjustable thermostat in place, it is not difficult to adjust the heat level. All you need is the proper screwdriver and a moment of time. To get a lower temperature, you turn the screw controlling the heat level to the left.

To get the heat level hotter, you turn it to the right. Finding the right heat level will take a few different tries as there are no numbers on the thermostat, just letters. That is all there is to it.

Just take your time in adjusting as it may be a while before the water heater responds to the new temperature setting. Testing will take longer than replacing the thermostat. If you are patient, you will get to the level you want.

RV Water Heater Thermostat Bypass


This has become a regular feature on most RVs and trailers. It is a simple system that allows you to cut off water from flowing into the water heater when you are storing or winterizing the vehicle.

All the bypass does is change the flow of water. It redirects the cold water line and has it flow into the hot water line and avoids any water from flowing into the heater. There are kits to do this work if your RV or trailer is not set up in this way.

You do not really want to bypass the thermostat. There is a good reason for this. Without the thermostat there is nothing controlling the water temperature and the heater can overheat and get damaged.

If the water is not getting hot enough and you have a dual-powered water heater, you can try to turn on both heating systems to make that water hotter. We are not sure if this will cause any problems or damage or not.

We have searched but we have not found any thermostat bypass option you can use. When you find that you do not have enough hot water, it may simply be that the water heater tank is too small.

Changing to a tankless version may be your best and safest option.

RV Water Heater Thermostat Troubleshooting

This process is not as hard or as difficult as it may sound. You do not need to be an expert to diagnose simple thermostat problems. The first step would be to check your power sources. You want to make sure they are turned on and that a fuse has not blown or a breaker tripped.

Next, you will want to check to see if you are getting any hot water after the tank has recovered and heated the water. Turn on your hot water faucet to check. If you are getting cold water out of the hot water faucet, then you have to check your thermostat.

Use the methods we already described above to check to see if the thermostat is functioning or has gone bad. If you do not know how to read a multimeter or do not have one, find a friend who can and does.

The multimeter will pinpoint your source and let you know if the thermostat is the problem. Once you determined that it is, you will have to go out and buy a replacement. You do not have to stick to the same brand and that might save you a little money.

Ask the clerks to help you find a compatible thermostat and then replace the broken one. This task won't take long and while you are at it, make sure to get an adjustable one so you stay in control of the water temperature.

Some Final Words

Many repairs on your RV or trailer are simple and easy to do. The thermostat is one of those repairs. it does not take a lot of skill to replace the part. It just takes you to be careful as you do not want to damage any plastic parts.

The key will be finding the replacement part that is compatible with your brand and model of the water heater. Having the part or serial number with you when you go shopping is essential in finding the correct replacement thermostat.

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