June 15, 2009

            John wants a cooler summer:   We're trying to decide between a whole house fan and a central air conditioner.  We live in a ranch style house.  Can you help?

            It's mostly a matter of your budget.  A central air system can cost $3000 to $4000, depending on several factors, including the location of your electric panel and the ease of access underneath the house.  The big advantage is that you create your own indoor air environment.  You get to close the windows and filter the air as it circulates through the furnace.  That can be a big help if there are  family members with allergies.  The operating costs, of course, can be significant:   maybe  $50 or more per month added on to your electric bill.

            The whole house fan installation will run you about 1/3  the cost of central A/C.  You can cut that down even more if you do some of the work yourself.  The big advantage, of course, is  its low operating cost (you only run it for a half hour or so in the evenings).  But, since you suck air in through the windows and doors, you do pull in pollen and other allergens from the great outdoors.  (By the way, don't use a regular light switch to run the fan--use a 1-hour timer so it will shut itself off before you suck carbon monoxide fumes upstairs).

            Here's another cooling trick in a ranch style home:  Install a "fan" switch on the thermostat and run the furnace fan continuously when you get home in the afternoon.  That will mix the (normally) 10 degree cooler air in the basement with the warm air upstairs.  After 20 minutes or so, the main level will be significantly cooler.

            Finally, how's your attic ventilation?  You probably don't have enough.  Add a couple turbines or gable vents to keep summertime attic temperatures below 100 degrees.

            Don's worried about a fire:   Lately we've been smelling humidity around our gas dryer.  The vent is about 18 feet long with three 90 degree bends.  Is this too much and should I be concerned?

            It really is too much.  There is a (thankfully) small risk of fire if the venting to the outside has too much resistance to the moving air stream.  Generally, you're allowed a 25 foot run to the outside with your dryer vent, but you have to subtract 5 feet for each right angle turn.   There is an exception:  If the manufacturer lets you get away with more footage than that, then the city will defer to those limits.   In your case, it's 18 plus 7 minus 15 = 10 .  So, you're about 8 feet over the allowable. 

            If yours is an older house in which you don't have the luxury of moving the laundry closer to the outside, you could add a booster fan to the ducting.  Check with your regular HVAC contactor.  Otherwise,  make sure you are using all-metal ducts and that you clean out the line several times a year.  

            Sharon is dying to paint:  Can I do the outside during this wet weather?  Do you like brushing or rolling or spraying?

            You might want to wait a week or two until this spate of storms has passed.  Then you should paint in the morning on days when there wasn't a storm the afternoon before;  try to wrap it up by noon each day.   If you have older clapboard style siding, you must apply a couple of heavy coats of primer on to those exposed beveled edges.  They are the most vulnerable part of the system, as they tend to delaminate and absorb ambient moisture from the atmosphere.  Follow that with a two body coats applied with a roller.   Spraying is OK, but you tend to end up with less paint on the house, and so have to paint more often