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How To Install Electric Hot Water Heater In Series With Boiler In 3 Easy Steps

You’re installing a new water heater in your washroom. But, you’re wondering if installing an electric hot water heater in series with the boiler is okay. And even if it is okay, you don’t know how to install an electric heater in series.

Don’t fret, we’ve got you covered!

How to install an electric hot water heater in series with a boiler?

It’s quite easy actually. First, find an ideal location for setting up your electric water heater. Place the vents above snow level and 12-inches away from any window. Set up the pipes according to their criteria. And lastly, set the temperature control on the heater.

All of the details can be found in the segment below. Like what you’ve seen so far? That’s great!

Dive right in and learn everything there is to know!

Things To Consider Before Buying A New Water Heater

It’s possible that a faulty heating element is preventing you from obtaining enough hot water. There’s a piece of data labeled on your old tank. That data will provide you with the size and energy specification of your heater. 

In case you ever have the need to replace it, you can do that very easily.

Now, you should check your home’s water pressure with a pressure gauge. 60 to 50 psi is ideal for a water heater. Before installing the pressure-reducing valve and expansion tank, make sure the water is turned off.

If you have to drain the water, check for brown water coming out of the heater. Also, size guidelines should be found in the manufacturer’s instructions.

How Does The Combination Of Electric Hot Water Heater and Boiler Work?

The basic equipment inside the combination is a stainless steel block with one gallon of water. There is this circulator pump that pushes the water through to be heated inside. These boilers tend to be much more efficient than your normal heater.

The basic difference between a normal water heater and a combination of water heaters is quite simple. And that is the domestic flat plate heat exchanger. 

Hot water heater and boiler combination use simple technology compared to burning fuel to create heat. Hot water heater and boiler combination also contain fewer moving parts. These boilers are powered by your main supplier.

You can go for a ceramic heater if you want. Ceramic heater efficiencies tend to outweigh other heaters.

Installing Electric Hot Water Heater/Boiler Combination

It’s simple to connect an electric hot water heater to a boiler in series. Just make sure you don’t misplace anything. 

Now, let’s set up that heater for you!

Step 1 of 3: Placing Your Heater and Vents

The location you want to put the boiler should have some hangers and plywood. There should also be gas piping and water piping. If everything is clear, you are ready to install the water heater and boiler combination.

You need to make two holes outside for the venting system. Through one hole, the flue gas will go outside. And through the other hole, combustion air will come inside. Also, check if you need a hot water heater stand or not.

Now, you need to make the PVC connections. There are some restrictions to putting the venting system outside of your house. The PVC pipes need to be above the snow line. So that when snow falls, the intake hole wouldn’t get blocked by the snow.

The exhaust should not be within 12 inches of any window. There should be a 1-foot gap between the intake and the exhaust. When you set up your exhaust, make sure it’s 12 inches away from any window.

Step 2 of 3: Setting Up The Pipes

There are a few types of piping in the whole boiler system. Hot and cold piping and the supply and return piping are the most important ones.

Identifying those pipes shouldn’t be difficult for you at all. These pipes usually tend to be color-coded. When you set up those pipes, make sure to set them up to their respective places.

There is also a different gas connection to the new combination boiler.

Step 3 of 3: Temperature Control

There is a modulating gas valve. It can modulate from 17,000 BTUs and go up to 75,000 BTUs.

You can always match the load you need for your house.

In case you need a new modulating gas control valve, we’ve listed some for you-

Product 1
Product 2

There is an outdoor temperature system used for balancing heating systems. You can use that to regulate heat between the water heater and the boiler.

If you want a big water heater, you can go with a 40 gallon one. But do check the size of breakers for a 40-gallon electric water heater.

Set all of them up and your work is done. Now you have electric hot water in series with a boiler.


Question: What to do if the boiler starts leaking?

Answer: If your boiler has an internal problem that might cause a boiler leak. The problems can happen with the pressure valve or the pump seal. If your system’s pressure is too high there might be leakage.

Question: Should I get a big water heater or two small ones?

Answer: You should get two heaters if you live in a big house. If you live in a tiny house though, a large one should suffice.

Question: Can I drink hot water from the heater?

Answer: Residential hot waters in the USA are drinkable. Water from any other place could contain chemicals.


We’ve told you everything about installing an electric hot water heater in series with a boiler. Installing one by yourself shouldn’t be much of a problem anymore. 

Make sure to go through our instructions properly and follow them accordingly.

Good Luck!