Seeking advice on adding central air

[Vmcw]

Hi!

We have a townhouse in Flagstaff, AZ, as a second home. It's two stories, about 1600 square feet, has a gas furnace in the attic. It's about a year old and the furnace has had very little use as it's basically our summer home.

Although most folks in Flagstaff don't have air conditioning, we're thinking of adding it for the few days in the summer when it gets uncomfortable. If you don't know the climate, it's relatively low humidity and rarely gets above 90 degrees. A day in the mid-90s is considered a major heat wave, and then it will drop down to below 60 at night. We're not talking about Phoenix-style weather, obviously, but we're getting spoiled as we age and do want to add the air.

I'm just asking for general advice, as I don't want to be totally ignorant when getting bids from contractors. What do I need? Capacity? Brands to look for? Brands to avoid? What should it cost? Is there someplace I can read up about this?

Thanks in advance!

Tom M.

[SQLit]

Phoenix-style

I spent last 4th of July up there and it was hideously hot with out any ventilation. Call several contractors and do some googling for the manufacture and part number of the furnace. You MIGHT be able to put in an "A" coil with the compressor on the ground outside. The coil will be sized to the furnace, if you can do this.

Contractor is more important than the brand. All manufactures make low end units to high end units. Low end tends to be nosier, and cost a bit more to run. Since your not going to be living there, I would get a 10-13 seer unit. Better check your HOA about regs before you jump off the deep end. Have fun.

[Bill]

There is basically the cooling capacity of the system and air flow to deliver the cooling to each room. Determining this can be quite complex depending on local weather, your windows, insulation, size of rooms and house, etc.

Problems can be too little cooling capacity, too much cooling capacity, too little cooling in some rooms and too much in others, and the upstairs/downstairs thing... Upstairs is too hot and downstairs it too cold. (In Phoenix, west facing rooms with large windows seem to never cool down in the afternoons, but may be too cold in the mornings...)

If there is too little capacity/air flow, the house will never cool down. Too much and it will freeze you out of your home. Just right will keep all rooms at the same temperature.

They may be able to just add on to your existing system or they may need to add to or modify your duct system to add more air flow.

They can do calculations and a report on what is needed. A sample report is at the link below.

I guess the best thing to do is to call for estimates from several different companies and see what each says. (May want to take notes.) Then ask back here if you have questions about what they said. Also may want to ask on alt.hvac

Note that you can also get a humidity control, electronic air filter, HEPA air filter for allergies, and temperature controls for each room (or separate temperature controls for upstairs/downstairs).

Temperature controls for each room requires installing electric air controls in the vents to each room.

Sample report...

Phoenix-style