Dreaded Cooling "Rule of Thumb"
Someday, I would like to condition three spaces in my country place in Northern California (i.e., cool nights and little humidity, but occasionally hot afternoons). One area measures 200 sq ft., and the other two measure 300 sq. ft. each. The house has a wrap around porch, so none of the areas experiences any heat load from direct sunlight. The house is well insulated.
While I consider a single supply system (as opposed to separate window mounted units in each area) I have three very preliminary questions:
1. What size air handler might I end up with?
2. Would more than one ceiling register be necessary to supply the conditioned air to each room?
3. If the duct runs to each room are modest (i.e., 10' to 20'), what size duct would likely supply the register(s) in each room?
Just to emphasize, I am not considering conditioning the entire house. I would be satisfied to achieve a modest degree of cooling in just the three spaces in question. For that reason and others, I already know that I don't want to add cooling to my existing furnace/warm air supply system.
Rules of thumb will just get you a brown thumb.
If you size by a rule of thumb, your window unit may be too big or too small, depending on your climate and insulation and glass exposure.
An oversized unit will not dehumidify well either.
Remember, Air Conditioning begins with AIR.
Thats what I like. A customer willing to spend as much money installing A/C for three rooms, as to do the whole house.
Have some contractors come out, and give you an estimate on what it will cost.
Is there really no ball park on cooling a few modest sized rooms with a single unit and duct system? As mentioned in my post, humidty and glass exposure are not issues at my place.
I would like to learn a little on my own before I ask installers to devote their valuable time working up a scope and price. With some effort on my part, I may learn enough to scrap the whole idea before I waste anyone's time.
Beenthere, I am not sure how to take your response. If you're being quick to judge, that's o.k. by me. In the end, the cost will be what it is (more, less or the same as a doing the whole house). This may not be one or them, but some of the best ideas I have had in the past have been ones that appeared flawed at first glance. As they say, the "devil is in the details" sometimes.
If this isn't the place to learn a little, no problem. Lots of folks still write books on the subject, and I haven't forgotten how to read. Thanks anyway for giving some consideration to my post.
The cost to install A/C for 3 rooms with a new system. Will be about the same as to install for the whole house using the existing furnace and duct system.
Rules of thumb lead to troubles later. Make you think something is possible when its not, or vice versa.
Can it be done. Sure. Should it be done, A contractor needs to see it to answer that.
You can call and ask your local contractors over the phone. Might be they aren't interested in doing it.