Adding a second zone to my Central Air?

[emies]

OK, so this is probably something people in the biz hear on a daily basis but I checked two pages of threads and didn't see it so...

I have Central Air and the upstairs to my condo is always warmer -especially the master bdrm since it has sun shining in all day. If I set the AC to 65 it gets pretty comfortable upstairs but the downstairs is freezing.

OK, question - Can I add a second "zone" upstairs to the pre-existing AC/heating unit? How do I tell if it will support it? How big a project is it assuming it can support it? Etc...

[GregH]

emies,

No, it is not practical to zone your existing system.
There has been an incredible amount of discussion here that relates to inadequate ductwork, especially in two story homes.

[TigerDunes]

GregH

Could you take a moment and explain why zoning is not practical for this common problem we see so often on this forum?

When is zoning a good choice?

And what if anything should emies do to improve to his condo's upstairs' cooling other than a window shaker?

[GregH]

emies,

The reason it is not practical to zone a forced air system is that for proper operation of the heating and cooling the furnace and airconditioner need a fixed amount of air flow.
Zoning by using dampers can cause a shortage of air if too many dampers are closed at the same time.
Because of the difficulty in heating and cooling a two story house effectively, a lot of larger two stories use two separate systems.

There are a few things you can try:

* Check to see that your fan is operating at the highest speed if it's a multispeed motor or the motor can handle an increase in the motor pulley size if belt driven.

* Make sure your filters and fan are clean. In checking the fan it is important to carefully look at the fins on the blower to make sure that dust is not caked on. (Make SURE the power is off before opening the furnace covers.)

* Adjust the dampers or grills to be fully open on the second floor and partially closed on the main floor. Make sure you don't close the main floor grills too much or you could starve the system of air.

* Try leaving all the doors on the second floor open to help airflow.

* Let the fan run continuously when the airconditioning is on. (This is what helps a lot with my two story house.)

* Depending on your upstairs and stairway layout it could help if you had a larger floor mounted fan directing air into the stairway. Just make sure it is not a tripping hazard.

* Make sure that you run the bathroom exhaust fan for awhile after bathing.

* Booster fans are an option if you can access the ducts going to the second floor. My experience with these though is they do not last very long.

* Last but not least you could look into the current state of your insulation on the second floor.
A large reduction in heat gain could be realized if your insulation is poor.

If you need help with any of this just ask.

[TigerDunes]

GregH,

more questions on zoning....

What is a good definition of zoning?

In your opinion, under what circumstances if ever is zoning a reasonable, practical,and economical choice for residential homes/condos?

Are you basically saying that zoning a 2 story home with one heating/cooling system is never a satisfactory decision whether on new construction or as an upgrade like emies asked about?

Thanks
:)

[GregH]

Tiger,

Why does this sound like a test??? :)

My hvac background is commercial, where the economics of zoning are taken from a different perspective.
As far as zoning a residential forced air system, I am only familiar with homes that use two or more separate hvac units.

Perhaps you can provide more detail on residential zoning and the work involved in retrofitting.

[mattison]

The problem I run into with a true "zoned" system in residential is lack of maintenance and residential service techs that don't understand the controls then you start running into serious airflow problems. It would in my opinion not be feasable to retrofit a system into a zoned system. With the cost involved they could just put another a/c unit in a closet or attic and have dual systems.


Now for the posters problem. I don't believe they were talking about true zoning like we are I think they are talking of adding another supply. What may help better than just adding another supply is having return air ducts installled in these rooms and try runnig the fan in the on position 24/7 for a while.

[kthor]

emies,

No, it is not practical to zone your existing system.
There has been an incredible amount of discussion here that relates to inadequate ductwork, especially in two story homes.


I don't want to start a new thread so I will post here..so my problem is
on my second floor, room 2 and 3 dont get cool enough when the AC is on
even when the ceiling fan are running..any suggestion to help with air flow ?
I was thinking of having one of the ductwork shutoff to maybe increase air flow to the second story, would this help? :alarm:

[GregH]

kthor,

Balancing the airflow with dampers might do it for you.
There are other suggestions in post #4.
Maybe someone has more to add.

[emies]

Lots of great info - thanks!

I have changed the filter and the unit was serviced less then a year ago - or so the tag says so I assume the blades on the fan should be pretty clean.

If I shut the bedroom door as well as the vent in the spare room when the AC is on it gets cool enough in the bedroom. The unit is pretty new and we are limited in space on where I could put a second one so I think I'll just deal with it the way it is for now. If/when I need to replace the current system I will make sure I get one that will address the cooling needs better.

Just have waaaaay to many other projects that would add value better and since this is a starter home (actually condo) and the main purpose is to build up enough equity in it to put down on a home in 3-5 years through appreciation and blood, sweat and tears - I will turn my attention to things like hardwood floors, tiling the bathroom floor and new kitchen cabinets....

Thanks again!! Have found this site to be very helpful and appreciate everyone comments...

[GregH]

emies,

If you are able to make the system work better by just closing one vent and the door I'm sure that some simple balancing of your duct dampers or grills is all you will need to do.
You could close all the grills on the main floor to say 1/3 closed and see what affect it has on the air distribution.

I don't think you will need zoning to make things work right.