Winterization of your sprinkler system is not an area that I would suggest skimping on, particularly up here where it gets cold. If you search around you will find that the recommended compressor stats (for simple residential sprinkler system blowouts) are 10-25CFM at 60-80 PSI, a little further research and you will find that a compressor of this type is LARGE and EXPENSIVE, $1000.00+. Vastly more than you would ever need for blowing up pool toys and bike tires. The volume of air is the crux for consumer grade compressors they just do not move *enough* air to clear the lines completely, the air will override the water leaving the pipe partially full of water, which accumulates in the low areas, and freezes... I know a few folks who use their home compressors and have had no problems, I have also reinstalled systems where the freeze damage was so extensive replacement was the only cost effective approach. BELIEVE me I am a do-it-yourself homeowner, in fact I just this weekend completed replacement of 50' of my house foundation which was do it yourself to the extreme. It is my opinion that winterization by a proffesional is well worth the money. Good luck

The equipment you posted is a approved match on the AHRI directory. Out of curiosity I also entered the 5 ton CBA38MV-060-230 model. Here are the results: The numbers seem strange, but the 4 ton air handler produces 57,000 BTU of cooling with a 18 SEER and 11.2 EER. The 5 ton air handler only achieves 55,000 BTU of cooling wit 17 SEER and 10.5 EER. In this case the 4 ton air handler outperforms the 5 ton model and is more efficient. I imagine the 4 ton costs less than the 5 ton. You Lennox contractor has done his homework by offering the better equipment. If you have more questions I suggest you start a new posting rather than tagging onto this old one.

I use compressed air to winterize our irrigation system. I can't imagine how a 'blower' would do an adequate job. Every fall, I disconnect the water supply and remove the zone valves (we freeze here in the winter). One end of a 1/2" drip line ends near our garage so I have made hose jumpers that I install between my compressed air supply and this drip line, and between the zone feed lines at the control valve box. I drop my compressed air supply to 30 psi and let it blow out the system for at least 20minutes, then disconnect the jumper hoses and store them for next year.

In terms of the system design i'm also wondering if it makes more sense to have two units with each floor having their own dedicated one though I know there are pluses and minuses to both approaches. I know from reading these forums that if we do go w/ a single unit that is zoned the compressor and air handler should both be two-stage or variable units and that a bypass duct system shouldn't be used. Is there anything else I should be asking or looking out for? HVAC zoning is primarily used when: The structure has an existing single HVAC system in a home with two or more levels or an expansive one level. The existing system is still operable, in this scenario. The structure does not have the room for a second HVAC system. If a system is still operable, adding another system to zone a structure will then "over size" the conditioning needed for the structure. So to do it right you would need to size the 2 systems appropriately for each zone they condition. Duct work: When zoning via a single HVAC system there are a myriad of ways in which to accomplish it. I believe much of this in my experience -- which is living in a hot humid climate in which air conditioning is required 9-10 months of the year. Given that, much more complicated for my climate, especially which these systems also operate heating as well as cooling. So if you live in a more moderate climate that uses air conditioning much less? you *may* have less trouble... unless of course you're facing an extensive heat wave. Much less means 3 months, maybe part of 4 months. (You mention Philadelphia, so your concerns are much different than someone in my neck of the woods in Katy, Texas) Your heating is an entirely different system (radiator)... so the zoning for AC is only going to come into play when operating the AC. Air conditioning is part mechanical removal of heat, and part movement of air. Air flow requirements are typically around 400 CFM of air per ton. While you can modify this some I personally would go no lower than 350 CFM per ton. What kind of equipment: If you choose single stage AC equipment, there is no efficiency gain when zoning. It's more about putting conditioned air where you want it. It's more about comfort in the zone or part of the house your in. Example: a 5 ton single stage air conditioner cooling 1 floor of a home is doing the same amount of work, if it were cooling the whole house. Example 2: a 5 ton 2 speed air conditioner can run in 1st stage most of the time, it might save you some coin, but not much. 1st stage is 70% of capacity of the machine. In a moderate climate 3 months need, you may break even depending on a host of various factors. Example 3: a 5 ton inverter will vary ramp up and down as the "load" dictates. So depending on climate again, how much you run it vs what you pay in utility costs can make this the better option. However, equipment costs are higher and repair costs will be higher as well. In zoning this option would be most efficient because ramping the compressor costs more and if you only have a single zone open? Choosing 2 separate HVAC systems: if one breaks you have a back up. Repairing two HVAC systems costs more to maintain, repair and ultimately replace when that time comes. HVAC zoning is complicated: The job I did that I talk about below... at least a couple different HVAC companies tried to repair it. (unsuccessfully) I did a HVAC zoning redo earlier this year. I gave the option of including an inverter AC along with new HVAC zoning. The customer decided to reuse his existing single stage AC as it was still operable and not in that bad of shape yet. He was completely happy with the job even though he decided to keep existing equipment the same. He was quoted $30,000 to fix this problem by more than one competitor. I also told him during the process that he could do the AC inverter later if he wanted to. I service the Katy, Texas area.