Dual HVAC System (hotel, townhouse, live)

[AnalyzeThis]

Does anyone have experience converting a single HVAC system to a dual system in their home? The previous homeowners replaced the HVAC system around 6 years ago but it seriously does not cool the entire home consistently, and if the temperatures outside are over 85 the temperature inside seems to stay around 79 regardless of the setting (74 degrees). We are thinking adding another zone would help given the size of our home. Any thoughts or experiences?

[kutra11]

Are you sure all the vents are open? And that the thermostat is working fine? Eliminate these cheaper fixes before you incur huge costs.

[ChristineVA]

No, I've never done it but I'm sure it would be pricey. You would have to run ductwork on the upper floor and, depending on how it works, you'd have to find a place to mount the second unit.

I have dual zone heating and have heard it is a *must* on homes 2400 square feet and above (not including the basement). I have lived in a much smaller townhome without it and the top floor was a REAL drag. Swore I'd never go without dual zone again.

However, I think your house is under 2400 square feet and you have a unit that is the right size for your home, you should not be that miserable. My friend upgraded his unit recently (his house is just at 2300 square feet) and he is pretty happy with the results. I'd probably try to figure out if you have a unit large enough for your home before I went to investing in expensive changes, although dual zone is nice so it may be worth it you. Mine unit is mounted in the attic (which is rare) and runs on separate ductwork that is built in the attic. That is probably the most feasible option. My friend's unit is in the basement along with her main unit and she has a separate system that runs from the downstairs into the upper floor.

[AnalyzeThis]

Our system is serviced regularly so we know there are no issues with the actual HVAC or thermostat. Our service guys say the size of the system is "adequate" but the bottom line is our home is over 3,500 sq ft not including the finished basement and I just don't see how one unit can keep both floors properly heated and cooled with the extremes in our temps. This is the first two story home I have actually had without a dual zone system, it is the one thing the previous owners skimped on.

Christine you gave me an idea to ask about maybe getting a unit larger than the one we have to see if it will force out more air.

Thanks to you both for the suggestions!

[jillybean720]

Our townhouse was three levels (well, including basement, which is where the a/c unit was). The top floor master bedroom was disgustingly hot in the summer, double bad because it had vaulted ceilings, so the sun was basically beating down practically directly on our ceiling all day. We ended up replacing our a/c unit with a stronger one than was recommended for the size of our home, and we installed a ceiling fan. MUCH better!

[lqda4]

Have you played with the dampers and tried to shut off the lower level in the summer month? In our previous home (single detach home but small), I kept the dampers to the main floor and basement closed and only let cool air flow to the second floor (and reverse in winter) - it worked out quite well.

[NC211]

We have the dual zone setup, its ok but requires attention to make sure you're not running of the all the time (heat rises, cold falls). That being said, whatever happened to the whole house exhaust fan? I think if homes still had these at their highest point, it would help to solve a lot of issues associated with the single zone hvac setup and the bio germ stuff that is sometimes associated with these new homes that are essentially wrapped in a plastic bag under the siding. I'm seriously considering having one installed in my home. The ability to turn it on and cause a real vaccum of airflow trouout the entire house to pull the stale air out, is pretty cool.

[ChristineVA]

Originally Posted by AnalyzeThis

Our system is serviced regularly so we know there are no issues with the actual HVAC or thermostat. Our service guys say the size of the system is "adequate" but the bottom line is our home is over 3,500 sq ft not including the finished basement and I just don't see how one unit can keep both floors properly heated and cooled with the extremes in our temps. This is the first two story home I have actually had without a dual zone system, it is the one thing the previous owners skimped on.

Christine you gave me an idea to ask about maybe getting a unit larger than the one we have to see if it will force out more air.

Thanks to you both for the suggestions!

Oh WOW, 3500 Sq feet and only one unit. That's a crime. I bought my house from Van Metre homes and the builder told me that they won't built a house over 2500 sq feet without dual zone. I know when we were house shopping there were many that did not abide by that.

[lqda4]

Also beware of people who tries to sell you a bigger unit as solution to all problems. You can stuff a 100-ton AC unit to your house and still have the same problem, if the ducting system is inadequate and poorly designed.

[Smoke_Jaguar4]

I would go with two units for redundancy. We came back from vacation and one of our units had a failure - This was during the July heatwave. The repair required replacing items which took some time to ship and install. With the functioning 2nd unit, we adapted and stay in our house instead of staying in a hotel (this would have been disruptive and $$$).

Going with two smaller units instead of one big one will also let you manage the the zones independently, which will save you electric costs and make your home more comfortable through the day.