Are The Water Heater And Furnace Connected

In as much as we love using hot water during the cold season, it is still preferable even in the warm season for washing dishes, clothes, and taking showers. However, do you know how your water is heated? We researched for you and came up with the following answer.

The majority of homes use the traditional water heaters to heat water in two ways:

  • Direct water heating
  • Indirect water heating

Let’s delve further and find out more about the connection between the water heater and furnace, the possibility of the water heater warming your home, the cost for replacing this equipment, and much more.

A water heater furnace placed on the basement, Are The Water Heater And Furnace Connected

How Water Heaters Work

Traditional water heaters are the most popular in many homes. Water is heated to a fixed temperature and then saved at that temperature until the hot water faucet opens to release the hot water.

All water heaters work more or less the same and can use electricity, gas, oil, or propane to heat water. In addition, they heat water directly or indirectly. Let’s unearth more on how this concept works, as explained below:

Direct Water Heating

Water heaters are large cylinders made from metal and have two pipes at the top. One pipe directs cold water into the tank and flows inside right to the bottom. It is then heated by the type of fuel inherent in the tank.

When the water is hot, it moves upwards to the top of the tank and flows out of the second pipe and afterward directed to a faucet that releases hot water when opened.

Let us look in-depth at how an electric and gas heater directly heats water:

Electric Water Heater

A residential water heater in the basement of a tan colored wall

Cold water that enters the water heaters is heated by the electric elements found inside the tank. The hot water rises to the top of the heater, and a flow-out pipe directs the water to the entire home to be  used when taps are turned on, for example in the shower or kitchen.

Gas Water Heater

The gas water heater uses the same concept as the electric water heater. The only difference is the type of fuel used.

However, in this case, the water heater has a gas burner that burns gas that subsequently produces hot air, which rises through a chimney found in the middle of the tank.

The movement of the hot air upwards in the chimney heats the surrounding water in the tank, and at the same time, releases this air outside.

The outlet pipe from this heater travels through the water piping system up to the faucets that release hot water when opened.

Indirect Water Heating

A high frequency furnace in a residential gas water heater

Indirect water heaters are slightly different from direct water heaters. In this case, the heating mechanism is not inside the tank but found outside, whereby water is heated in a furnace or boiler.

The furnace or boiler has a pipe that transports the hot water into the heat exchanger, which is found in the water heater or storage tank. This heat exchanger is what heats the water inside the water heater.

Boilers or furnaces not only use electricity and gas but can also use propane or oil to heat the water.

How Far Should A Water Heater Be  From A Furnace?

By and large, the clearance around your furnace should be wide enough to allow easy access for purposes of repairing and sometimes replacement of the furnace. Most building codes require that furnaces should have at least 30 inches of clear space from the walls.

A furnace requires enough air supply to feed the combustion flame. Thus the room should not be too small, and the ventilation should be good.

Some building codes require that the electrical disconnect switch and shutoff valve for gas lines be in the same room as the furnace. The codes may further recommend that the electrical shut-down be the actual switch and not a cord plugged into the electrical outlet.

Keep the area around your furnace free from any items that are easily combustible such as cleaning and laundry products, papers, rags, sawdust, wood scraps, or used filters. In addition, keep away anything else that you may deem highly inflammable such as gasoline, paint, or thinners.

Does The Water Heater Affect The Heat In The House?

Your water heater can be used to not only heat water but also your home. However, this option is most favorable if you live in climates that are not too cold, and your house needs to be properly sealed and insulated.

To have this type of system requires  you to use a combination boiler, which is a single unit that can heat water and also warm your home. The heat can be controlled to the temperature required by turning the dials or pressing the buttons to the desired position.

Electric circuit boards and a wiring along with a boiler in the boiler room

If the temperature starts falling below the point it was set, the thermostat sends out a signal to the boiler to increase the heat to the desired level. When this point is arrived at, the boiler modulates itself to keep the heat at the right temperature, thus saving energy.

The house and water are not heated at the same time using this system. It will either heat your radiators to give out warmth to your home or heat the tap water, which always takes the preference.

When the hot water is turned on, the valve inside the boiler redirects the heat into the hot water supply system to provide hot water through the taps. When the tap is turned off, the valve is re-routed back to the radiators in the central heating system to continue heating your home.

Does A Water Heater Give Off Heat?

As shown above, you will need a combination water heater if you want to heat the water flowing through the taps as well as your home. If you opt to use this type of system in your home, the benefits are as follows:

Hot Water When Needed

You do not need to store water anymore, as the water is heated instantly when you open the hot tap.

Saves You Space

You do not need extra space for the hot water cylinders because they are no longer needed. Instead, the water is instantly heated as it flows out of your taps.

Small In Size

The modern combination boilers are less cumbersome. These are built to fit in small spaces that are out of sight, for example, in the cupboard.


Many manufacturers today have improved on the efficiency of this type of system, moving from a G-rated model to an A-rating, which will also help you save on energy bills.

High Value

The price of installing this type of system will be cheaper than the traditional boiling system because no additional tank is required.

How Much Is It To Replace A Furnace And Water Heater?

A water heater and a boiler in the boiler room

Whereas the costs vary depending on the type of installation or repairs required, generally to install a gas water heater is from $250 to $700. The cost per hour is likely to be around $80 per hour.

On the other hand, installing an electric water heater would generally cost between $1,100 and $2,100.

And if you want to switch from electric to LPG hot water heaters because they are cheaper to run, you will spend between $1,200 and $3,000.

It costs between $2,000 and $7,000 to replace a furnace. In some extreme situations, the price can go upwards to $40,000. 

For a better picture of the costs involved, consider:

  • replacing a gas furnace is between $3,800 and $10,000,
  • an electric furnace would cost between $2,000 and $7,000 to replace
  • replacement costs for an oil furnace are from $6,750 to $10,000

Due to the variance in prices, it is recommended to get at least three quotations to arrive at the most affordable price for the best service.

In Closing

A water heater furnace placed on the basement

The conventional water heaters can be found in many homes, and they operate either directly or indirectly to heat water. A combination boiler comes in handy when you not only want to heat water but also your entire home. This is an improvement that combines the traditional furnace and water heater together and operates from a single unit.

The costs to install and replace a furnace and water heater vary. Thus it is important to get quotes from different contractors to arrive at a price where quality is not compromised and that is most affordable as per your budget.

Check out our previous posts and find out how to reduce humidity using a furnace and why they are fitted with filters:

Does A Furnace Fan Reduce Humidity?

Do All Furnaces Have Filters?



Share this article

Leave a Reply

Your email address will not be published. Required fields are marked *