Direct Vent Water Heaters vs. Power Vent Water Heaters

Four key differences you should know about.

Direct vent water heater vs power vent water heater, what’s it going to be? If you have no background in water heater systems, these terms are bound to confuse you. What do they mean and why can’t we just pick up either, install it and enjoy our hot water?

There are several things you need to consider when purchasing a new water heater. One key consideration is how hot (waste) air will be eliminated from your home.

We’ll briefly describe how each vent works and point out key differences between them.

Hot Water Heater Basics

Water heaters that burn natural gas, propane or oil require a venting system. This is because the fuel that burns to heat your water releases by-products, including carbon monoxide, which is highly poisonous (1).

The venting system is responsible for safely removing these dangerous gases from your home. Different water heaters have different types of ventilation. These include an atmospheric or standard vent, direct vent, and power vent, among others.

Here, we’ll be comparing the direct vent water heater against the power vent water heater.

Direct Vent Water Heater

For combustion to take place, the heater requires air which can be drawn from inside or outside your house. Direct vent water heaters draw their air from the outdoors, combustion takes place, and the waste gases are then returned outside.

Some models have a large flexible pipe that runs from the heater through an adjoining wall to the exterior of the house. Within the large pipe, you’ll have a smaller pipe whose job is to carry waste gases outside.

Other models use two flexible pipes — one for air supply and the other for hot air removal. This type of venting offers you a sealed system with no possibility of backdrafting.

What is Backdrafting?

Backdrafting occurs when hazardous gases flow in reverse through the vent pipe. These harmful gases find their way into living spaces and could fatally harm the occupants.

How does it happen? Hot air is lighter than the surrounding cool air and as a result, it rises through the flue and leaves the home. There are certain situations when the indoor air pressure becomes too low.

This may be caused by the expulsion of air at a high rate through appliances such as dryers and fans as well as fireplaces. The low indoor pressure causes harmful gases to be sucked back into the house.

Backdrafting occurs as a result of poorly configured flues as well as blockages within the flue (2).

Power Vent Water Heater

Power vent systems derive their combustion air from inside your home. They use a fan or blower to expel gases through a sealed vent that’s installed horizontally. The gases can also be expelled vertically through a pipe to the roof.

Power vents shouldn’t be confused with power direct vents. The latter comes with two pipes — one for deriving air from outside and the other for expelling waste gases (3).

Since power vents draw their air from within, they need to be located in an area that experiences good airflow. As with the direct vent water heaters, power vent units also use a sealed system to prevent backdrafting.

Direct Vent vs. Power Vent: What Are the Differences?

It’s important to know these key differences to help you choose the best system for your home:

1. Heater Location

Direct vent heaters should normally be located a recommended four feet away from an adjoining wall, as they use natural air flow. This distance can vary depending on building codes or the model (4). Power vents have longer flues that can reach up to 40 feet.

If your direct vent uses a chimney to expel air, you’ll need to have the heater located near one. Power vents don’t use chimneys but need to be in rooms with adequate air flow.

2. Operational Costs

You may find the power vent water heater hiking your electricity bill since electricity is required for the fan to run. This is not the case with direct vents that work with the principle of hot air rising over cool air.

Initial installation costs of a power vent heater are also much higher. You’ll need to factor in the cost of the fan and pipes, among other costs. If you’re looking for a budget-friendly option, the direct vent water heater system is worth considering.

3. Noise

Power vents produce some noise while the fan is running. This occurs whenever the water heater is in operation. It may not be distracting for you, but it’s worth noting.

Since direct vents ‘breathe’ in and out naturally, there’s usually no noise from them.

4. Efficiency

Power vents are far more advanced than their direct vent counterparts and will deliver more benefits, including higher energy efficiency and venting flexibility.

That said, it’s worth remembering that power vent water heaters require electricity to function. You can expect to see a hike in your power bill as a result.

Which One Is Better?

Direct Vent Water Heater vs Power Vent Water Heater — is one better than the other? It’s hard to say really, as it depends on your current needs, where you live, and even building codes, where applicable.

At the end of the day, both venting solutions offer a sealed system which is of great importance. With the information we’ve provided, it’s over to you to choose what works best for your home.

Do you have any questions or comments? Let us know in the comments section below. We would love to hear from you. And remember to hit the share button!

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About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.

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