Hi all, I want to fit a wall a/c unit in our living room. There are two possible positions for the unit, neither is ideal but it's all that are possible. one is near a corner with 34" from corner to door trim. The other has about 50" from door trim to corner BUT the door would open towards the unit. Of course, the door will never be open while the unit is on and I could fit a baseboard stop to prevent contact but it seems ugly. So, which is the better of the two poor options? oh, the right hand door pane does not open - it's fixed. thanks! [attach]84757[/attach] [attach]84758[/attach]

I want to know when to change the air filter in my central heating/cooling system. I'm feeling frustrated by the advice I see when googling this, because the advice mostly makes no sense to me. The most common advice seems to specify some fixed time frame, from every 20 days, or once per month, or every three months, etc. This makes no sense to me because it fails to take into account how often the system is used (hardly ever in spring or fall here), how dusty the location is (central desert vs. shoreline), what kind of filter is used (simple fiberglass, 1" pleated, 5" pleated, etc.). Advice that recognizes these factors is remarkably imprecise as to how much of an adjustment should be made for them. The people giving this type of advice mostly seem to have an incentive to recommend unneeded air filter changes. Why change air filters at all? As far as I can figure out, the answer is that if they get so dirty that it impedes the air flow, then the heat/cool exchange becomes inefficient and could even be damaged. (Or, sometimes odors build up in the filter so it should be changed, especially if there are pets.) Sensibly, considering how expensive HVAC systems are, they would have a little pressure or air flow sensor and when it detected that the filter is clogged enough to impair the operation, a signal would be sent to the thermostat and a little icon or red light would come on, labelled "change air filter." Since I have never seen or heard of this, obviously that basically doesn't exist (and, certainly it isn't part of my house HVAC). I have seen add-on gauges for sale online to provide objective evidence of the air pressure drop caused by the filter, however installation and access would be problematical for me, as my air return (with filter) is on a high ceiling, directly below the rooftop HVAC installation. (I did see a review by someone who had successfully installed one of these aftermarket gauges, celebrating that there was no meaningful drop in air pressure after her air filter had been in place for a year.) I saw one answer that seemed to make sense, especially as it is similar to how I make the decision about when to change my car's air filter ... by visible dirt load. Has anybody out there tried this approach? The advice was: #1--Have a new air filter on hand. #2--Occasionally remove the current air filter, then hold them both up to sunlight. If the current air filter is visibly darker, it should be discarded. Another approach (which I don't trust, because I just made it up) is to use a hand-held anemometer (air speed gauge). I'd check the air speed (at either the return or a supplyl vent) with the old filter in place, then replace the old filter with a new filter and see if the air speed changes. If it doesn't, then the old filter can't be slowing the air very much and could go back in. Anybody ever heard of this approach? Would an inexpensive, hand-held anemometer likely be sensitive enough to measure whether there's enough of a drop to warrant changing the air filter? Thanks for any assistance you can provide.