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High velocity system owners!

Posted by chscl (My Page) on
Thu, Jul 5, 12 at 21:37

This is the first summer in our new home a 1945 colonial. . The previous owners had installed a high velocity system. Much to our chagrin the house doesn't cool down that much! The first floor seems to cool down better , but the second and third floor is just plain weak.
We have two condensers and two handlers . One that is just for the first floor and another one for the entire second and third floor. The air that is blowing out of the ducts is cold but we think the problem may lay in the fact that we don't seem to have enough ducts in each room. For ex: one Br that is approx 11'x14' has two ducts , and our LR which is around 14'x17' has 4 ducts. Not sure why they installed it like that?! Also we don't have ducts in our foyer and hallway either....?! Anyways, needless to say we are not happy with this situation. :( Just wondering if anyone has any input or suggestions on what we can do ...could we add more ducts and get a bigger condensor? Or it is what it is? Any opinions on your experience with these type of systems would be greatly appreciated.


Follow-Up Postings:

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RE: High velocity system owners!

Are you able to ask the previous owners on how that system cooled the house? Where are the return air ducts located? Did you have a reputable service tech. check the system? What is the temp. of the supply air coming from the supply vents?


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RE: High velocity system owners!

Unfortunately I dont think we will able to ask the previous owners..

I am assuming when you say return air duct you mean the air handler (sorry, I am a noob at this whole CAC business)
We have a return air duct located in the basement which is for the 1st floor. And we have a return air duct on the 3rd floor which is for the second and third floor.
We had a run of the mill AC guy come look at it and he basically didnt have much to say except it is what it is (?!) Having said that, he didnt seem to be that knowledgable of these kind of systems.
We are located in NYC - so if you or anyone on this board have a tech to rec that would be greatly appreciated.

btw- not sure what you mean by temp of air coming from supply vents...TIA


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RE: High velocity system owners!

"ot sure what you mean by temp of air coming from supply vents"

Hold a decent thermometer about 12 inch below the high velocity outlet and see what it eventfully reads.

An 'instant read' kitchen dial unit should work reasonably quickly.

You may have a poorly designed high velocity system.

When correctly designed and installed they work very well.

So well outlets in corners that will not blow on anyone are preferred.


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RE: High velocity system owners!

The temp on one of my LR outlets read 68F. But some of our vents seem to be stronger than others. My husband put tape over areas where there may be leaks. But if there is a vent leaking between the walls , how would we ever know?
That's what I am afraid of , a poorly designed system . What are my options to fix that? Add more ducts to blow out more air? And what if is a damaged duct inside the wall? How do they fix that?


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RE: High velocity system owners!

Unless the blower is running between compressor cycles, 68 seems way too high. Turn the t-stat way low and take temps at outlets and at the return.


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RE: High velocity system owners!

"The temp on one of my LR outlets read 68F. "

WAY to high.


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RE: High velocity system owners!

:(
Any ideas on why this is happening and how we can get the air to come out colder?

We are so bummed . This is our first summer in our new home and a CAC overhaul isn't in our budget.

When we had the house inspected the inspector did mention the unit was about 10 years old.


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RE: High velocity system owners!

When did you buy the house? Is is possible that the previous owners knew of a leak and had the system charged, but not fixed.


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RE: High velocity system owners!

10 years meas nothing.

Start checking both the main trunks and the flex line take offs for leaks.

Che and the return ducting the air temp going into the the return also.

High velocity systems can leak on the cool side, but the higher pressure (around 2 inches of water pressure) makes the leaks almost always out of the ducts, not in.

The system should be able to make at least 20 degrees of temperature drop (and even 30 is not out of line) from the inlet to the ducts.

Incorrect charging would be a god first check.


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