Can you use a tankless water heater with well water?
The short answer is, yes, you can.
The longer answer is the point of this article.
You will have to take some things into consideration and maybe even make a few adjustments before you buy. When you have your ducks in a row then even you can enjoy endless hot water when using well water!
There are a few things about well water that make it unique that need to be accounted for when installing a tankless water heater.
Without further ado, let’s explore what you need to do to make this happen.
Why a tankless water heater has special needs
Since a well does not operate the same way as city water, and a tankless water heater doesn’t operate like a tank system certain things are not going to jibe.
A tankless water heater has a computer that adjusts on the fly inside so it isn’t as simple an operation as a tank. This is a good thing and a bad thing, but the reason it does is to provide the endless hot water that people love so you never have to worry about being the last one in the shower.
This computer is complex and has certain requirements with pressure and temperature that have to be met.
These two things make it more of a challenge to work with a well.
Another consideration is that your well water is not usually treated. If your well water is hard it will require more maintenance to keep your tankless running at peak performance.
Also, unlike a tank system that allows sediment to settle at the bottom of the tank, you will need to filter your water before it enters the tankless.
In essence, the three things that have to be dealt with before you can install are:
- The temperature of the incoming water
- The water pressure coming from the well
- The quality of the water, ie whether it is hard or has lots of sediment
Once you have these things dealt with then a tankless water heater will work out just fine.
Let’s go into all the details of each.
Tankless Water Heaters and Pressure
Just about every well owner has a pressure tank. This is essential to maintain a certain pressure so your fixtures don’t have water coming out irregularly.
Imagine taking a shower that alternatively sputters water on you and then shoots it like a jet.
This is not only inconvenient, but it will also keep your tankless water heater from working properly.
The computer needs to register a constant flow of a certain pressure to work properly. If your pressure is too low, then it won’t even fire up so you won’t have any hot water at all. (Source)
Even when the pressure is workable, if it fluctuates then you will have a fluctuating temperature of the water. Without a steady pressure, the heat exchanger won’t be able to properly heat the water as it rushes through. You’ll be hot and cold all throughout the shower.
That water pressure tank needs to be working well and maintained for your tankless water heater to work.
The required water pressure is going to be different for each model so make sure you check what your water pressure is from the pressure tank and what the model you are looking at requires.
Generally speaking, a typical well pump will give you a low of 30 to 40 psi and a high of 50 to 60 psi.
You may be tempted to check your water pressure by using a gauge on the valve on the top of the tank. This may not actually indicate the pressure because it doesn’t check the pressure above the diaphragm.
With newer tanks, this is rarely an issue but older tanks with corroded rubber diaphragms will definitely need to be checked by a professional.
If you have an old pressure tank and are thinking of installing a tankless water heater then this is a good time to think about upgrading your tank.
You may even need to buy a water pressure regulator to make sure the pressure is as steady as possible.
Know your size
Knowing what size tankless water heater you need is essential no matter what the circumstances. When you are dealing with well water it is even more vital.
I wrote an extremely detailed article with everything you need to know about how to determine the size you need including a calculator to do the math for you. You should definitely read that before buying, so click here for that.
I’ll give you the quick version of why it is important.
You will see the GPM or Gallons Per Minute listed for each model. Remember, you are not dealing with a tank so your only concern is how many gallons of water flow you need at any one time. If you are running 4 showers per day your GPM is going to be very low unless you are running them simultaneously.
The temperature of the incoming water plays the biggest part of how many GPM you’re going to get. The lower the water temperature coming in, the less GPM you will get.
That 10 GPM your tankless says it gets is usually when the incoming water is warm, like around 70°F or so. If your water is coming in at 40°F then you’re going to see a dramatic drop off with GPM.
Best Tankless for Well Water
When you are dealing with potentially cold well water coming in then I highly recommend getting a gas tankless water heater.
Electric ones don’t offer up the same GPM as a gas since it takes more energy to heat the exchanger.
If you do decide you want an electric, maybe because you don’t have access to gas or propane, then you should think about getting a few point of use ones and place one directly at the fixture where you need them. You can read my article with reviews of the best ones by clicking here.
The reason I suggest gas or propane is to get the highest GPM you can get. The tankless that gets the highest GPM is the Takagi T-H3-DV-N Condensing.
It is a condensing unit so it is highly efficient and will work as a whole house water heater even in cold climates.
Take a look at my list of the best gas tankless water heaters to see if there is one there that better fits your needs. Just remember to look for the highest GPM you can get and you should be covered.
Dealing with Hard Water
Many of you will be dealing with hard water when it comes to using a well. And with hard water comes problems for your tankless water heater. You can use a tankless water heater no matter how hard your water is, but you’ll need to make sure you are doing a flush once per year to keep it running at its peak and prolong its life.
This really isn’t as bad as it sounds. It only takes an hour or so of your time and can be done yourself.
To make your life easier, I recommend going with a tankless water heater that has isolation valves. This is basically a bypass from the water supply so you can flush the heater without shutting your water down for the whole house.
Some tankless water heaters come with them already and some need to be bought separately.
The other alternative is to use a water softener. This can either be a filter that sits just before the tankless so the water gets softened before it enters, or you can get one that covers the whole house.
With one of these, you never have to worry about hard water affecting your tankless and will ensure all of your appliances last longer.
Get a Sediment Filter
Having a filter that will remove any sediment from your well water is crucial. A tank system can let the sediment fall to the bottom of the tank and it will keep running. This is not the case with a tankless.
There is literally no place for the sediment to go so it clogs the heat exchanger. This can not only impact the lifespan of your tankless, but it may even prevent it from working at all.
Remember that the inside of your tankless is quite complicated and needs to be free of debris and scale build-up to keep working.
Depending on what kind and how much sediment you are pumping into your house, you can filter it out easily with one of those.
If you have been hesitant to go for a tankless water heater with a well, then I hope this article has opened your eyes to the possibilities. You can enjoy endless hot water with a well, whether the water is cold or hard.
You just need to plan ahead a little bit and make sure you have everything in place to get the most out of it.
If you have any questions about this or anything else tankless water heater related then just drop a line in the box below and I will get back to you as soon as I can!