Duct sealing and balancing

harley101 · 11-13-2008, 04:26 AM

Hello everyone first time poster here.

I am in the process of sealing up all my ductwork in our 7 year old rambler home in central Minnesota. A little background... 2700sf rambler forced air system with transite basement heat. (ductwork under concrete and floor vents in the basement. We had a Carrier Infinity 96% furnace and infinity T-stat installed last year for 2 reasons. 1~ replacing our 80% furnace should save us on propane. (96% is more than 80% right, grunt grunt!) and 2~ We were told that the Infinity features a DC induction and blower fan that will provide a higher static pressure to force the warm air down and thru our basement vents for more even basement heating.

Let me tell you I was amazed at how many gaps and spaces I found in the duct seams and joints while crawling around within the suspended ceiling of my basement. I am using a duct mastic and painting it on every joint and seam paying close atention to plenium joints. I tend to be sort of a perfectionist so no gap will go unnoticed.

So I fugure I have about 2/3 of my system sealed and never noticed how many dampers are in the system. Probably one just before each register, plus 1 on each the main supply and return plenium, and 1 feeding the transite plenium. So I'm thinking that I will get better flow If I have wverything wide open for better flow, but now I'm thinking I may have thrown things out of balance.

My thermostat is pretty cool and will show me the static pressure and CFM as the furnace is running. I show 0.76 static with everything wide open and a brand new 5" media filter. So what the heck does 0.76 static pressure really mean with this system? And how can I balance things more accurately than "this room feels colder than that room" I have access to magenahelic gages that I can fit to my supply and return pleniums.

I would love to get everything adjusted so ideally we are comfortable during the heating season as well as the cooling season without having to make damper adjustments, although I wouldnt mind having a summer setting and a winter setting and have to switch damper positions 2x a year. Just trying to get things more betterer.

Marvin Gardens · 11-13-2008, 12:11 PM

How much money do you have???

There is always a solution to everything. In your case you would probably want to go with a zone system. While these are not cheap they are within reach of the average homeowner. Most cost between $1000 to $3000 depending on things like access, size of system, number of zones and other factors.

First identify the problem.

In the winter you have a cold basement (I know I grew up in Minnesota and know what -40 feels like) which is hard to overcome since you have tons of concrete fighting against your attempts at heating it. In the summer the basement is nice and cool and you fight to cool the upstairs.

The upstairs is pretty equal year round. You have to heat it in the winter and cool it in the summer.

Zoning the basement and upstairs is probably what you want to do. This would allow more heat to be directed to the basement in the winter and more cool directed towards the upstairs in the summer.

Depending on your duct setup you can probably get by with a zone panel and 2-4 baffles. Cost would be in the range of $1500 or so.

Or you could just put in manual baffles for around $100 and have a summer/winter setting.

harley101 · 11-13-2008, 08:14 PM

Good point I know zone systems well as we had a 2 zone system in our last home 3100 SF 2 story walkout. It used a Honeywell mini zone control board and 2 water furnace (I believe) electric dampers. I almost took it with us when we sold the home.

We had a contractor install it and I think the bill was $1200 or $1400. It did make a big difference in the home. I saved some money by running the new t-stat wire from the second story to the basement eliminating the need for a wireless second floor t-stat.

I have since seen the identical controller on ebay for $300 or so and dampers run around $125

I thought of zoning our current home the same, Installing it myself would be no problem. but our new thermostat is holding me back. I think it has the capilibity to be it's own zone controller in itself, but the damn thing is like a freaking blackberry. The more I try reading the phonebook sized manual the more confused I become.

I probably would need to go with a Carrier branded zone controller paired with my current equipment, but I haven't researched it yet, since everything communicates. That should be a new thread. I think I would have a hard time getting one to install myself without having a contractor installing it and being Carrier branded it will probably not be cheap.

Marvin Gardens · 11-13-2008, 08:24 PM

This is a nice option. I have done a lot of zone systems and no one has ever regretted it. They don't like the bill at first but once the pain of that is over they are happy.

Installing them is not that hard. Just make sure that you get the wiring right or the upstairs will be real hot the basement will be freezing.

harley101 · 11-13-2008, 08:35 PM

Are you familiar with the Carrier Infinity system? Would I need to go with a Carrier branded zone controller? I just dont' want to lose some of the cababilities of the Infinity system by mixing equipment that may not me 100% system designed.

Marvin Gardens · 11-13-2008, 08:44 PM

I am not familiar with the Carrier system. I use the Honeywell zone control and have put it on a lot of different systems.