DIY Home Improvement Forum banner
1 - 4 of 4 Posts

· Registered
239 Posts
Discussion Starter · #1 ·
I live in a small townhouse that was retro fitted with an centralized system. Although the heat works fine in the winter, the house doesn't cool nearly as well in the summer. I've had several pros look at it and their opinions ranged from putting in a whole new system to nothing will work since the duct work is poor. I currently have a 2 ton system in a 1200 sq. ft house so the last HVAC person stated that it should be enough and suggested that i simply install some booster fans in the ducts to help move air. 2 questions comes from that is:

1) is that a good solution?
2) how do I find some rectangular booster fans since most of the pipes are rectangular?

· Registered
17,815 Posts
Booster fans are a waste of money; they won't solve the problems.

What problems are you having with the system?

Lack of cooling? Uneven cooling? Capacity issues?

You said the ductwork is poor - do you know if it's undersized? If supply isn't proportional to heat gain?

First thing to do is make sure the unit is actually supplying the 2 tons of cooling.

Airflow and wetbulb duct return and supply air temperatures need to be measured. The airflow, you can't measure without specialized tools. (there's a way around that if you have electric resistance heat and know the wattage)

If it's providing the 2 tons of cooling, go ahead and look at ductwork - balancing, possibility of replacing trunks if they're undersized, etc.

In a townhouse with the furnace or air handler at the back, you will get airflow issues especially if the unit only has a 1/5hp 800 cfm blower.

It's rated for 800 cfm only if the ductwork is done perfectly, you use fiberglass filters.

If the ducts are undersized, you may need a 1/3 hp 1200 cfm rated to get proper airflow.

Most furnaces these days come with at least 1200 cfm rated blower; all 1.5 to 2 ton air handlers don't, as well as a lot of < 60 000 btu furnaces.

Info on duct sizes, layout may help get us a better picture of what's happening.

Key is getting someone in who understands system performance and doesn't just want to sell you something. Most of them, especially if they make a comission will want to sell you a new system to rectify duct issues.

You can remove a 2 ton, have a new 2 ton installed and get similar or worse performance.

· Registered
8,922 Posts
Duct booster fans are great. They do a fantastic job of raising your energy bill, make your house sound like a B29 during takeoff, and starving other areas of airflow.
In other words, they are a band aid for the real problem.

· Registered
15,740 Posts
A booster fan may or may not help. They do consume electricity and can be noisy depending on where and how it's installed. You can make square duct fit to round duct, so inline fans will fit.

It's often not easy to install the fans due to finished drywall. It is also a Band-Aid solution.

The preference would be in increase air flow through the ductwork. This may be easier said then done, and may result in higher wind noise. The real solution is to fix the ductwork while increasing static pressure. This isn't the cheapest option.

Depending on location and local rules, a mini-split may help. You'd use it to cool the upstairs. They are efficient and quite. The electricity they consume is often offset by not running the downstairs blower all the time.

All of the above is DIYable if you have the will. More detail is needed to really offer real suggestions.

1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.