Done CORRECTLY the zoning is the only way to achieve control of up and downstairs. You can zone with a damper system or you can zone with multiple units. The issues of noise and reliabilty all hinge on the quality of the product and contractor chosen. One thing if you choose a damper system is you should use a dual capacity outdoor unit(A/C) Running the indoor fan(s) 24/7 with raise the humidity in your home during the cooling season. So what do you have the appetite for and/or you willing to compromise comfort and control for the up front savings. If you are concerned about repair/ownership cost buy a FACTORY extended warranty that will cover the complete system.(equipment and zoning) The decision making matrix will consist of several items but only you can bring your priorities to the forefront. First cost, level of control, warranty, energy savings, brand, reputation, and ..........................................
We often condenm that which we do not understand.
Not sure if anyone straight out condemned zoning.
But since the duct system is already set up for 2 systems.
Zoning with one 2 stage heat, 2 stage cooling system isn't really going to be anymore cost effective upfront.
2 systems may allow closer sizing.
Either method done right will work. Just more chance of it not being right by zoning.
quick question for the OP, what is your main reson for looking into replacing both systems now? A complete system for both floors is the ideal set up to have but would more than likely also cost more. My suggestion is that if the upstairs unit is working properly then look into replacing the downstairs system only and having the a/c added to it. This way you will have 2 complete systems (upstairs will be older) and you can have the other system replaced when you are financially able to. You dont have to do both systems at the same time. Yes it would be nice to do both at the same time but we cant always just get everything at once. I have had several customers replace one complete system, pay it off in a year and then do the other. Nothing wrong with that.
Originally Posted by jrock52766
That's a good point that I guess we had dismissed because we were on the track of merging the ductwork. The "do it in one shot" approach.
There are a variety of reasons to proceed with replacement (i.e. gov. grants, improved efficiency, lower operating costs, moving a condenser that's in the way of new deck, etc. etc.). It's not that we're not financially able to replace both right now, it's more a matter of selecting the right combination of solution/comfort/value.
Having 2 condensers outdoors consumes quite a lot of space (things are a bit crowded around the house already)....but it sounds like the ultimate solution.
I also need to ask the contractors to equalize their proposals a bit. For example the Zone Controlled solution includes all premium options XC15 vs XC13. HC15 vs. common 5" filter pack. G71 vs. G60, etc. Cased coil vs. custom. Perhaps only a couple hundred dollars per tweak, but when added up, they change the picture.
Lot's of variables and I'm sure if I called a 4th contractor I would get another option. We have time on our side, so I can evaluate further solutions and even visit existing installations.
The consensus seems to be that a single replacement unit will not maintain comfort without automated zoning control. When comparing the cost of that, it may be more versatile to simply install two fully independent furnaces and A/C units.
I appreciate everyone's comments and suggestions. Thank you.
with 2 systems you can better manage you utility usage . using digital programmable t stats I would not downgrade to 1 system