DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (http://www.diychatroom.com/)
-   HVAC (http://www.diychatroom.com/f17/)
-   -   Help - High Static Pressure & Keep getting Possible foil coil error (http://www.diychatroom.com/f17/help-high-static-pressure-keep-getting-possible-foil-coil-error-156233/)

kolo 09-08-2012 04:50 PM

Help - High Static Pressure & Keep getting Possible foil coil error
 
Hi,
I live in a about 4200 total Sq feet house and each floor is 2100sq feet each with duct pipes being 5in in diameter. I was getting high static pressure errors and my static pressure was like 1.03 to 1.10 and I got some work and its at like .79 to 90 when its fully running. The work I got done was I got 3 more returns put in and they also made some modification to duct so it was gonna push 60% upsatirs and 40% downstairs to help blanace the flow in the house. I have a two story house with a crawling space and thats where the furnance is located. Front of the house we have big windows on both floors and the downstairs is still colder and some of the registers are closed. I was thinking of adding some dampers to cut some the flow going to downstairs to help it out. Also the 3 returns upstairs dont have to much suction but the one I got added has good suction. Could some help me please and thoughts or suggestions.
My current readings are:
Airflow: 1400
Blower Rpm: 1099
Static Pressure: .89

beenthere 09-08-2012 09:16 PM

Have the upstairs supplies increased to 6".

kolo 09-09-2012 12:12 AM

Is there another way or solution, cuz if I replace 5 inch duct with 6 inch duct I'll have to rip out the dry and patch it up.

hvac benny 09-09-2012 12:58 AM

One option is to replace what you can access. Whether that will be enough or not is a different story.

kolo 09-09-2012 01:05 AM

I do have access to the 4ft crawling space so I see all the duct work thats there. If I installed dampers to the registers thats are casing the problems would that help.

beenthere 09-09-2012 06:24 AM

Adding dampers and then choking them down to force more air whee you want it will cause higher static pressure.

Marty S. 09-09-2012 06:28 AM

Quote:

Originally Posted by kolo (Post 1006067)
I do have access to the 4ft crawling space so I see all the duct work thats there. If I installed dampers to the registers thats are casing the problems would that help.

Probably not. The duct is too small to handle the air volume needed,hence the high static. Installing dampers to restrict some runs even more doesn't sound like a good idea.

beenthere 09-09-2012 06:53 AM

The reason those rooms with poor air have poor air flow is your supply trunk line is also too small.

kolo 09-09-2012 11:42 AM

Wow thanks for the quick respones, So if I understand you guys properly there's not to much I can do to bring the static pressure down even a little bit, unless I get new 6 inch duct work done.

beenthere 09-09-2012 12:15 PM

When we measure static pressure, we are measuring the amount of resistance to air flow. So in order to lower static, either the amount of air flow must be decreased, or the size of the duct work increased.

You could increase the size of your supply trunk line, or install a helper duct for your supply trunk line.

kolo 09-09-2012 12:53 PM

How would I install a helper duct for your supply trunk line. Also would it be pretty costly. I also have a carrier infinty 58MVB unit and if I change the settings from comfort to say efficiency would the kind of help.

beenthere 09-09-2012 01:04 PM

Quote:

Originally Posted by kolo (Post 1006328)
How would I install a helper duct for your supply trunk line. Also would it be pretty costly. I also have a carrier infinty 58MVB unit and if I change the settings from comfort to say efficiency would the kind of help.

Efficiency setting moves more air then comfort setting, so that wouldn't help.

A helper duct is another duct that runs beside the main trunk, and then taps into it at about the 3/4 length mark. To provide more air to the end supplies.
Sometimes it can be a small 10" round.

kolo 09-09-2012 05:27 PM

So it would 10 inch round and what would the length be ?

beenthere 09-09-2012 05:38 PM

Depends on how long your trunk line is.

On a 30 foot long line, the helper might be 22 foot. On a 25 foot, might be 18 foot.

The helper carries the air that the main is having trouble carrying. And generally ties back into the main about 3/4 of the way don the trunk.

kolo 09-09-2012 05:58 PM

I see, if you dont mind me asking why wouldn't the helper be tied right behind it instead 3/4 of the way.


All times are GMT -5. The time now is 09:18 AM.


Copyright 2003-2014 Escalate Media LP. All Rights Reserved