There are many venting options available for your home, depending on the appliances and systems you have in place. You may not know what sort of system you have in your home, but it’s worth finding out; optimizing the venting system at home can save you a lot of money and prevent accidents from occurring.
A furnace and a water heater can share a vent. The answer depends on the type of furnace you have, how efficient it is, and the size of its current venting system. Renovating your system so that these appliances share the same vent can save space in your home and save money in the long run.
In the rest of this article, I’ll discuss the advantages of vent sharing with standard efficiency furnaces, the B-vent solution, how this can help if you have a high-efficiency furnace, and the disadvantages of vent sharing in your home.
Is It Possible for a Standard-Efficiency Furnace and Water Heater To Share a Vent?
It is possible for a standard-efficiency furnace and water heater to share a vent. In general, if you have a furnace of standard efficiency (less than 80%), the chances are that your furnace is probably already sharing a vent with your water heater.
There are two types of vent for shared systems: the Concentric Vent and the Standard Atmospheric vent.
It’s always a good idea to check with a local licensed professional what kind of vent you currently have to determine if you want to change the system.
Standard-efficiency furnaces and water heaters sharing a vent can eventually save you a lot of money on bills.
It provides a space for both the appliances to expel the toxic exhaust gasses generally released outside the house — this is especially important for the furnace, which emits carbon monoxide.
Most homes in the 20th century were built with sharing vent systems.
However, since there are more options for appliances nowadays, it’s worth double-checking if the vent system needs to be updated or the vent size isn’t big enough to incorporate both the furnace and the water heater.
High-Efficiency Furnaces: The B-Vent Solution
Suppose you have a standard-efficiency furnace that is currently sharing a vent with your water heater, and you would like to upgrade to a high-efficiency furnace (more than 80%).
In that case, you’ll likely need to change the vent system, even if the furnace and water heater are already sharing it.
When you remove a low-E furnace to replace it with a high-E furnace, the likelihood is that the vent will actually be too large to accommodate this and the water heater.
The best solution to this problem is called a B-vent.
The B-vent is a vent that extends out on two sides, allowing two different sources to push gasses into the same vent.
Essentially, the B-vent is a large vent fitted with one pipe inside another, keeping the exterior pipe cooler than the inner pipe.
An air space between the two pipes allows each tube to remain at different temperatures and serve different purposes, depending on the appliance with which they connect.
To change the pipe system yourself at home, you must understand precisely how it works and what safety tips to bear in mind.
What Are the Disadvantages of Vent Sharing?
Safety concerns are the disadvantages of vent sharing at home. A vent system contains harmful gases to the exterior of the building. If these gases escape into one’s home, they can be very damaging to the occupants’ health and, in large quantities, could be fatal.
Furnaces are usually located at the bottom of the house, perhaps in a cellar or basement.
Meanwhile, water heaters are either outside or on the ground floor.
Because of the differences in location, the two appliances couldn’t possibly share a vent, and thus it is not an option in many cases.
Because furnaces have the possibility of a backdraft (when harmful gases go backward into the house), there are some safety concerns.
Additionally, vent sharing is not possible if your furnace is mechanically vented.
As well as this, it’s not possible to pair a gas furnace and a water heater if the vent is made from plastic.
PVC vents that operate with high-E appliances contain a lot of pressure and so it’s often unsafe to consider using one vent for two separate hardware.
Final Thoughts
Your furnace and water heater can indeed share a vent; however, certain precautions must be taken before making this decision.
It’s entirely dependent on the efficiency of your appliances, the material your vent is made from, and whether your devices are electric or gas.
Consider renovating your system to ensure your furnace and water heater share the same vent, as this can help you save space in your home and save money in the long run.
