Help with AC choice for Northern CA
I could really use some help from your wise ones!
We are adding 1000sqft and are sizing an HVAC. This 1000sqft space is a kitchen/family room with vaulted ceilings, a small bedroom and bath. Think of it as a 1-bedroom apartment. This new space connects to the rest of the house in a very open way to the dining/living room (about 550 sqft). The old part of the house is on a 13 year old furnace with alumaflex ducts run mostly through the attic but under the crawl space (rodents) for the master bed/bath (the furnace was installed when we added the MBR).
Standard 2x4 framing (yes, we probably should have gone with 2x6 but we are adding to an existing 2x4 house). The new remodel will have a combination of cellulose and foam insulation at R-19 (ceiling) and R-13 (walls and floors). We live in a moderate climate in Northern CA where the need for AC is just a few weeks a year. We don't have AC in the current house. We do have one person in the house who has some moderate-severe allergies (living in the house while the addition is being built is causing problems because of the dust).
Originally, our spec called for hydronic radiant heat, but for various reasons (primarily budget) it fell off the list. Instead we are opting for gas forced air and want to take advantage of air filtration that the system can offer. So now the question is what is the best way to do it.
We think we should add the 550sqft of living space to the new furnace and keep the old furnace just to heat the bedrooms (we keep those rooms cold at night and they are rarely used during the day anyway) so will have a new furnace serving about 1550sqft. The HVAC contractor recommended a TRANE XV95 80K 3ton, 2 stage variable speed system with one of their higher end air filter systems.
While in our climate the system will mostly run in the 1st stage, there are times when we would use the system at the 2nd stage for air cleaning - essentially running the unit to clean the air during high allergy season.
For AC, he recommends a Cold Point system
So here are my questions:
1) is that the right size system or is it overkill? It seems from what I've read our requirements are right on the line and we could possibly go for a smaller unit - although the cost differential is only about $150.
2) Does anyone have experience with the TRANE air filtration systems? Specifically their Clean Effects?
3) We've never had AC so I don't really know the differences, but this system seems outdated. Plus it appears it uses an R22 which is being phased out. The reason he is suggesting this system is because we have very strict city codes for noise and can only have a unit that is less than 64dB. Does one even exist that could meet this requirement? We have lived without the AC for 20 years and don't really need it, but as we age the allergies seem to worsen so we thought we'd take advantage of the switch from radiant to gas forced air by getting AC. Should we scrap traditional AC?
Any advice is greatly appreciated.
Thanks in advance!