How Does a Furnace Vent Fuel? Three Kinds 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 exterior by way of a vent pipe (additionally referred to as an exhaust flue) system.

There are three kinds 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 varieties is the temperature of the flue gases.

Should you’re asking your self why the exhaust gases must 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

You probably 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 regular effectivity furnace and is roughly 70% environment friendly.

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

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

On the damaging aspect, pure draft vents are extra conducive to backdrafts, which reduces effectivity and could be 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 rapidly, with the aim of serving to the nice and cozy flue gases vent to the skin.

There may be airspace between the inside and outer metallic pipes which offers insulation in opposition to warmth loss to maintain the hotter flue gases naturally drafting.

The outer pipe is product of 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 doubtless a direct vent and makes use of an exhaust fan.

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

The flue pipe on these furnaces is just sheet metallic and will 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 exterior utilizing an induced exhaust motor, which implies that they don’t must be hooked up to the chimney and will 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 power from the combustion course of as doable.

As a result of 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 of 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 of acidic, so please make certain to empty them accordingly.

Single-Pipe vs. Two-Pipe

two pipe vented gas furnace

All propane and pure gasoline furnaces require adequate carbon dioxide for the furnace to succeed in full combustion.

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

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

The issue with that is that the furnace might expend all the air within the room.

So, it is because of this that native codes are in place to make sure adequate air is accessible for single-pipe heating methods.

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 at all times has sufficient combustion air.

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

For the most secure HVAC system doable, 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 exterior of a residential house

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

Different points can embrace 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 might trigger any of the above points to happen.

Most furnaces as of late have security switches in place to show the furnace off earlier than any harm might come up.

🛑 What’s The Hazard?

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

Nonetheless, a blocked or cracked flue pipe additionally has the potential to flow into carbon monoxide into your private home.


🔥 Last Ideas on Furnace Venting Methods

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

Typically, I might 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

Should you discovered this text on furnace vent varieties useful however you’re nonetheless searching for extra info, I might suggest contacting a extremely rated and skilled native HVAC firm to ask for assist.

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

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