High velocity HVAC

[5030tinkerer]

Has anyone ever heard of this? At the local builder show in Des Moines, a vendor was indicating that if you have an ICF house with radiant heat flooring, you shouldn't be looking at anything other than high velocity HVAC systems using 2" ducting. He claimed that the reason for the larger ducts was for heating, not cooling. Does anyone have any experience with this? He was also saying that these ducts should be pointed at the windows (where the heat or cooling load would be) rather than out into the room? Any thoughts?

Ed

 

[beenthere]

Makes some sense to me. What part of it bothers you?

 

[frank29]

</font><font color="blue" class="small">( ............He was also saying that these ducts should be pointed at the windows (where the heat or cooling load would be) rather than out into the room? ......)</font>What follows may not be applicable; but, I think it MIGHT apply. I had a car with a good A/C system. A vacuum hose broke....this resulted in all air flow being routed through the defroster ducts. When it was a hot sunny day, the A/C could not keep the interior cool. The hot window was cool; but, the passenger compartment was not. As soon as I replaced the vacuum hose and could route the air through the dash ducts, the A/C would run you out of that car.

 

[5030tinkerer]

Nothing about the concept bothers me, it's just that I had never heard of it before. The idea of having 2" ducts in my new home seems interesting (if nothing else from an ease of installation perspective), but I am not interested in duct whistling or blow-you-over wind force when the thing kicks on.

 

[beenthere]

That wouldn't be favorable to me either. Maybe find a house where such a system is demo'd to check for noise. The 2" 'pipes' seems would be possible to insulate as well, not losing 'cool' air as it moves through the system. I like cool air but I don't like to feel a cool breeze or 'wind' in the house.
I have a wall unit (compressor outside) and I like it, except for the amount of air that it gets moving. Probably an engineering compromise necessary for the best efficiency of the system.

 

[ronjhall]

On the local home improvement radio programs in the Detroit area they are always recommending a product called Spacepak. I have seen it in homes that have hot water heat. It was very quite.

 

[Freds]

I agree with the others on the noise factor, plus it would take a heck of a blower motor to overcome the friction, also adding to the noise in your house. Interesting idea, though. Lots of restaurants, offices and such go with med-high velocity systems with sealed ductwork.
If I was going to run a 2" pipe in my house it would be a piece of PVC to a closet. /forums/images/graemlins/smile.gif

 

[PineRidge]

On the up side We had a lot of praise for units of this type when they were installed in commercial applications like restaurant's. Also the fact that the cool air is dumped overhead makes for a very efficient system. And small 2 or 3 inch diffusers that are easy to place and easy to hide are attractive to some businesses.

On the down side Unfortunately any time you increase air velocity the noise level also increases proportionately with it. /forums/images/graemlins/frown.gif They are a complaint waiting to happen in a residence. Imagine the air rush in the middle of the night when the house is still and your trying to sleep and you'll get the idea.

 

[Jagmandave]

I thought the main advantage to this stuff was for older homes, where it's difficult if not impossible to run regular ductwork.............

They use it all the time on This Old House, but they always talk about how much quieter it is than regular systems........

It's interesting to me because I'm getting ready to start building my ICF home, and I was planning to just use a regular, high efficiency FAG HVAC system........

 

[PineRidge]

I think the main advantage is ease of installation. Using flex duct cuts labor dramatically, over conventional hard pipe that has to be cut with shears or snips and then insulated once run.