Hi – the heat and humidity index have risen dramatically this week. So of course we are realising that our AC simply can’t keep up – we moved into this house a few months ago.
So – what single improvement or combination of improvements should we do first?
The options are:
1. Replace 80s era AC unit
2. Add insulation in attic (there is some, but not much and the walls are not insulated, but they’re plaster so I’m leary to punch holes in them for blown in insulation)
3. Add attic fan.
Help! We have limited funds, so would like to do whatever has the greatest impact on our comfort levels. The house is holding a fairly consistent early 80s temperature when it’s mid-late 90s outside. At least it’s keepingt he humidity levels down!
Cheers
mj
Replies
Sounds like the weather here... if its the mid 90's here already, I'm sure not looking forward to August...
Tell us where you're at. Maybe that would be a good start.
Get an HVAC guy in. Its VERY hard to believe that the system was never able to pull the house cool in mid-90's weather. I'd have him look for 1) low coolant levels (this is VERY likely!), dirty filter, dirty a/c coils ("A coils") in the air-handler, and clogger condensate drains.
Also, make sure your registers are wide open upstairs....
I second the advice to get the unit checked out and serviced to asssure that it performs as well as can be expected. Be sure the evaporator (inside) coil is thouroughly cleaned, the system filter(s) are all changed (with good, pleated filters) and the unit has the appropriate refrigerant charge.
As far as the improvements go, insulate and vent the attic first (after the AC system "tuneup".)
If by an "attic fan" you mean a "whole house" fan. Those can help maintain some comfort in cooler temperatures by moving air through the house and "exhausting" the hottest air near the ceiling, but often they cause more harm than good. I would not put one in my house. If you meant a power ventilator to remove hot air from the attic, in the absence of other means of attic/roof ventilation, not a bad idea. I prefer soffit & ridge vents, but not all roof systems are well suited for such.
1. Replace 80s era AC unit- Have it checked by a couple or three HVAC firms; I don't like to have only one opinion when $4-$5,000 are involved
2. Add insulation in attic (there is some, but not much and the walls are not insulated,- After airsealing, bring it up to at least R25 to R40 depending where you live. Use blown cellulose. Are there ducts in the attic?
but they're plaster so I'm leary to punch holes in them for blown in insulation)- Don't be!! The 1" holes from using smaller cellulose equipment are nothing to finish and re-paint. Airseal at the walls also. Uncontrolled air exchange accounts for a fair amount of cooling loads as well as heating loads. You don't want to heat or cool the air and then lose it!!
Hey guys - thanks for the quick replies. I should have mentioned that I'm in the DC area. Plus, this is a 1939 house that was retrofitted for AC in the 80s - so poor location of vents, only one register in the entire house. We did get the AC serviced when we moved in, but of course have no idea how well they did it, although this company had always been good in the past. But they did quote 6-7K for replacement, so you can see why I'm looking for alternatives. No idea also if the size of the unit put in is appropriate for this size house (not large, but two storey) - the previous owner wasn't too much into maintenance or spending much on the house, unfortunately.And yes, I'm thinking an attic fan - nto a whole house fan. We had one in our prvious house and it did seem to make a difference.mj
I think attic fans are a waste of time, money, and electricity. Blown in insulation is pretty cheap. A lot of places will loan you a blower if you buy insulation from them. Blowing some insulation in your attic should make a lot of difference. I'd definitely look into getting some insulation in the walls as soon as you can afford to. It might be easier to blow some in from the outside rather than the inside, depending on what kind of siding you have.Sealing up air leaks is also a good idea. Doing things like spraying foam around ceiling fixtures (in the attic) will help keep your cool air in.Shade trees on the south and west sides of your house will also help. But obviously that's not a short term solution.
Go after life as if it's something that's got to be roped in a hurry before it gets away.
And yes, I'm thinking an attic fan - nto a whole house fan. We had one in our prvious house and it did seem to make a difference.
Take the $$$ going to be used on the fan and put it into attic insulation- lot's of it!!! R49 YIKES!!! See the following website:
http://www.eere.energy.gov/consumer/tips/insulation.html
The high economic levels recommended surprised me. Must have upgraded since the fuel price rise. The insulation will negate the need for a fan and it doesn't use electricity year after year after.......... Plus it'll save on heating costs also.
Edited 5/31/2006 10:25 pm ET by experienced
I'd like to second everything that experienced said. His knowledge is cutting edge, and his advice right on the money. It may fly in the face of some orthodoxy, but that's 'cause we in the building trades tend to be conservative, not because he's wrong.Andy
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