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Forced air heating

I have a forced air system in my house. We just finished off the upper level of the house and have opened the vents up there. The problem is that there isn't enough force to push the warm air sufficiently to the 2nd level. Is there a induction fan of some type that can be added to the system to give it more of a push from the basement?

Re: Forced air heating

There are in duct fans and fans that set on the registers available on-line and in most big box stores. However this problem is generally caused by the system not being balanced. That is the dampers on the duct runs need to be adjusted to get even air flow or the wrong size ducts are installed..


Re: Forced air heating

To be honest --- you 're going about this the wrong way.

The first thing should have been to have your forced air system evaluated to accomdate the extra load before finishing the upper level. The system needs to be large enough to provide heating btu's and air ( CFM's ) to accomodate the extra square footage --- are the supply ducting large enough and are there enough for the extra rooms ? --- is there enough return ducting available? --- are the existing ducts leaking ?

To answer your question --- there are duct booster fans avilable.
However, this is not a proper way to resolve your issue. These booster fans are known to be unreliable and produce less than desirable outcomes.

These booster fans only serve to be a band-aid approach and really shouldn't be considered as a proper method of resolving your HVAC shortcomings ---- in my opinion.

Re: Forced air heating

Actually when the house was built, the duct work was carried to to the upstairs level expecting that the upper level would be completed at some time in the future. So I've assumed that the air handler was sized accordingly. The downstairs is warm, but the air force coming out of the registers upstairs is less than desirable. All the dampers are open in the basement. I'm hoping not to have to replace the system if possible.

Re: Forced air heating

I know what you're describing as it was common here as well back in the day.
However, the ducting that was installed --- say 50+ years ago -- wasn't likely sized accordingly and usually not enough. The common complaint that folks like yourself have after doing the upper level is not enough air flow.

Just because ducting was in place doesn't mean it's correct and isn't leaking.

Assuming the HVAC was sized to accomodate the additional space is not a wize thing without having it checked first. It may have been installed with only the pre-existing living space at the time.

If it happens to be sized properly to accomodate the extra square footage , the blower may be able to increased in speed.

To be honest ( again ) --- you should have a HVAC professional perform cfm calculations required for the additional space along with evaluating and testing the upper ducting.

Re: Forced air heating

I agree with the others but would like to add that the length of the main trunk as well as the length of the supply runs comes into play, as well as the design. If you have a one duct system and the length to the last runs is to great you will lose air or get air that is not as hot as the air from a supply that's closer to the furnace. If it's a two duct system and you have an equal amount o supplies on each Main Trunk your furnace should be centralized. To get the most out of your system your Main Trunk should be the Duct Reducing Type. This will keep the pressure within the duct and if sized right give the required cfm's.
All this being said you should have a load calc done, as canuck points out), to be sure you have the right sized unit. There are a number of free load calc programs on the net, just keyword the same. Most of the time this type of problem is because of an unbalanced system. If balancing doesn't help a good HVAC Contractor should be able to help you out. Good Luck :)

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