Should I Replace the HVAC?

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Something that is very important in a home is a working HVAC (AC, furnace, and vents). When this is not working together properly, the house does not heat or cool the way it should (there could be other reasons too: insulation & drafts doors/windows). Something we noticed in our home after buying it was that the air was not circulating properly. And come to find out it was a combination of vent placement and trunk line sizing. So I would like to help you answer this question should I replace the HVAC?

Are you wondering if you should replace your furnace or AC?


Before I start I want to let you know what a couple of items are first that way you know exactly what I am talking about.

HVAC: is heating (furnace), conditioning (AC), and ventilation (where all the air comes from).

DUCT: a channel or tube for moving something

TRUNK LINE: is the main line from the furnace. Think of if like a tree; a tree has one trunk with many branches (ducts in our case!).

RETURN VENTS: allow air to flow back to the HVAC system; helps circulate airflow!

Hopefully, those terms will now make sense when we talk about them.


There could be many reasons or one reason to replace the HVAC in your home. And when I say HVAC that could just mean your furnace needs to be replaced. So how do you know what to replace? Let’s look at things that maybe need to be fixed or replaced in your home.


Normally the duct in a room (air supply) is placed along an outside wall. A common place in below a window.

In our home all the ducts are along the inside wall making it really hard to push air to the outside wall, meaning each room in our house would only heat/cool half of the room.

If the duct in a room is not close to an outside wall, this could be a really good sign that your duct placement should be changed.


Return vents are something almost every room should have if you want a good circulation of air. Think of it like the human heart; blood is circulated through the body then back to the heart. An HVAC system needs the same thing.

Most return vents are by the inside wall of a room. If a room is not circulating the air properly it could use a return.


This one takes into play the whole HVAC system. The number of ducts (and their size), the furnace type, and AC type. The first two items (ducts & returns) are something you could replace but to get the proper size of a trunk line, I would recommend a PRO! Have the PRO size the trunk line and maybe even build it but then you install it (this is what we did!).

I wish I could tell you if you needed this replaced but there are so many factors that need to be looked at that I would suggest calling out a company to give you a bid and they should be able to tell you if you need it replaced. Just remember that you can install it to save money.


Maybe you have a dated furnace or AC that needs to be replaced because it is not efficient or it could die any day.


All of these reasons where why we replaced our whole HVAC system in our house. The furnace & AC was old, around 27 years. The trunk line was too small for the number of ducts we have. We only had a couple of return vents for our whole house. And the vents were not placed on the outside wall. Plus we wanted to add more ducts in the basement.

So do you need to replace your HVAC system? Or do you need to replace some of it?

PS. Stay tuned for how we replaced the trunk line ourselves and installed the ducts!

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