How Does a Furnace Vent Fuel? Three Forms of Venting and How They Work.

🔥 How Does a Furnace Vent Fuel?

Propane and pure gasoline furnaces, whether or not they’re mid-efficiency or high-efficiency furnaces, will vent exhaust gases outdoors by way of a vent pipe (additionally known as an exhaust flue) system.

There are three sorts of venting that we are going to focus on on this article; pure draft system, direct vent system, and energy vent system.

The primary distinction between the three vent sorts is the temperature of the flue gases.

In case you’re asking your self why the exhaust gases have to be vented, it’s as a result of the method of burning fossil fuels can create poisonous gases like carbon monoxide.

🔥 How Older, Much less Environment friendly Furnaces Vent Fuel

Pure Draft Furnace Vent

CC Image by Bonnie Bogle through Flickr

In case you have a furnace that has a metallic exhaust pipe, often known as a B-vent pipe, which comes out the highest of it, then your furnace is taken into account a normal effectivity furnace and is roughly 70% environment friendly.

These furnaces have a much less environment friendly warmth exchanger and due to this fact have extraordinarily sizzling combustion gases that naturally draft out the flue pipe to the skin.

The exhaust pipe is often routed by way of the chimney and out by way of the roof.

On the detrimental facet, pure draft vents are extra conducive to backdrafts, which reduces effectivity and is usually a security concern.

What’s B-Vent Pipe?

furnace b vent pipe

B-vent makes use of a double wall of metallic pipe.

The inside pipe makes use of reflecting aluminum which heats shortly, with the aim of serving to the nice and cozy flue gases vent to the skin.

There’s airspace between the inside and outer metallic pipes which supplies insulation towards warmth loss to maintain the hotter flue gases naturally drafting.

The outer pipe is fabricated from corrosion-resistant galvanized metal.

This ensures power and sturdiness.

Direct Vent

Old Furnace

In case your metallic exhaust vent is routed out of the home, it’s seemingly a direct vent and makes use of an exhaust fan.

This kind of furnace has a barely extra environment friendly warmth exchanger that’s roughly 80% environment friendly; due to this fact, the combustion gases have a decrease temperature and need assistance getting vented to the skin.

The flue pipe on these furnaces is simply sheet metallic and may be extraordinarily sizzling to the contact.

Native codes are in place to make sure that the venting pipes don’t are available in direct contact with flamable supplies.

What’s a Direct Vent Furnace?

A direct-vent furnace has a self-contained, sealed warmth exchanger that warms inside air by the house’s air throughout the sealed warmth exchanger.

The combustion byproducts are then vented outdoors utilizing an induced exhaust motor, which implies that they don’t have to be connected to the chimney and may be put in on most exterior partitions.

🔥 How Excessive-Effectivity Furnaces Vent Flue Gases

Gas furnace combustion chamber in action

A high-efficiency furnace makes use of a major and secondary warmth exchanger to take away as a lot warmth vitality from the combustion course of as attainable.

Because of the decrease temperature of the combustion gases, a metallic exhaust pipe is not wanted.

Subsequently your high-efficiency furnace makes use of both a single-pipe or two-pipe vent system.

These propane or pure gasoline furnaces are thought-about to be at the least 90% environment friendly.

One of many challenges with high-efficiency condensing furnaces is that the combustion gases find yourself condensing on the within partitions of the PVC pipe, drain again to the furnace, after which out the condensate drain line.

The combustion by-products have a excessive PH stage and are thought-about acidic, so please make sure that to empty them accordingly.

Single-Pipe vs. Two-Pipe

two pipe vented gas furnace

All propane and pure gasoline furnaces require ample carbon dioxide for the furnace to achieve full combustion.

If there isn’t sufficient, then combustion byproducts may embody carbon monoxide, which might be toxic to your loved ones.

A single-pipe heating system makes use of combustion air from the house across the furnace.

The issue with that is that the furnace may deplete the entire air within the room.

So, it is because of this that native codes are in place to make sure ample air is on the market for single-pipe heating programs.

NOTE: All propane and pure gasoline furnaces have the aptitude to be put in with two-pipe furnace venting.

Many contractors will solely set up a single venting pipe system when a two-pipe system ensures that your gasoline furnace all the time has sufficient combustion air.

Ask your HVAC contractor what they do earlier than accepting their bid.

For the most secure HVAC system attainable, request that your furnace’s exhaust have two pipes.

PRO TIP: Most areas require particular high-temperature PVC pipes to be used on high-efficiency furnace installations.

🔥 Blocked Or Broken Exhaust Pipe

Furnace horizontal vent termination kit
Furnace horizontal vent termination equipment fitted outdoors of a residential house

If the flue pipes are blocked or broken in any method, the combustion course of might create carbon monoxide.

Different points can embody flue venting cracking or joints failing.

What could cause a vent pipe to get blocked?

Bugs, small animals, bushes, snow, or ice can simply block the furnace venting, which may trigger any of the above points to happen.

Most furnaces lately have security switches in place to show the furnace off earlier than any harm may come up.

🛑 What’s The Hazard?

A blocked vent pipe may solely make a furnace brief cycle and nothing extra.

Nevertheless, a blocked or cracked flue pipe additionally has the potential to flow into carbon monoxide into your house.


🔥 Last Ideas on Furnace Venting Techniques

Clearly, making a call on what kind of furnace to purchase has extra variables than simply the venting system, but it surely’s undoubtedly one to contemplate.

Usually, I’d say {that a} direct vent is the least costly possibility.

It’s simpler to put in than a pure draft however isn’t as environment friendly as a system with one or two PVC flue pipes.

Phyxter Approved Logo on Service Truck

In case you discovered this text on furnace vent sorts useful however you’re nonetheless in search of extra info, I’d advocate contacting a extremely rated and skilled native HVAC firm to ask for assist.

Guarantee they completely clarify their suggestions for furnace sizing and vent sorts.

Wish to study extra about your house’s heating system? Be at liberty to take a look at our different furnace articles!